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Sample records for bluefin tuna thunnus

  1. Hearing thresholds of swimming Pacific bluefin tuna Thunnus orientalis.

    PubMed

    Dale, Jonathan J; Gray, Michael D; Popper, Arthur N; Rogers, Peter H; Block, Barbara A

    2015-05-01

    Pacific bluefin tuna (Thunnus orientalis) is a highly migratory, commercially valuable species potentially vulnerable to acoustic noise generated from human activities which could impact behavior and fitness. Although significant efforts have been made to understand hearing abilities of fishes, the large size and need to continuously swim for respiration have hindered investigations with tuna and other large pelagic species. In this study, Pacific bluefin tuna were trained to respond to a pure tone sound stimulus ranging 325-800 Hz and their hearing abilities quantified using a staircase psychophysical technique. Hearing was most sensitive from 400 to 500 Hz in terms of particle motion (radial acceleration -88 dB re 1 m s(-2); vertical acceleration -86 dB re 1 m s(-2)) and sound pressure (83 dB re 1 μPa). Compared to yellowfin tuna (Thunnus albacares) and kawakawa (Euthynnus affinis), Pacific bluefin tuna has a similar bandwidth of hearing and best frequency, but greater sensitivity overall. Careful calibration of the sound stimulus and experimental tank environment, as well as the adoption of behavioral methodology, demonstrates an experimental approach highly effective for the study of large fish species in the laboratory. PMID:25732931

  2. Atlantic Bluefin Tuna (Thunnus thynnus) Biometrics and Condition

    PubMed Central

    Abid, Noureddine; Addis, Piero; Alot, Enrique; Andrushchenko, Irene; Deguara, Simeon; Di Natale, Antonio; Gatt, Mark; Golet, Walter; Karakulak, Saadet; Kimoto, Ai; Macias, David; Saber, Samar; Santos, Miguel Neves; Zarrad, Rafik

    2015-01-01

    The compiled data for this study represents the first Atlantic and Mediterranean-wide effort to pool all available biometric data for Atlantic bluefin tuna (Thunnus thynnus) with the collaboration of many countries and scientific groups. Biometric relationships were based on an extensive sampling (over 140,000 fish sampled), covering most of the fishing areas for this species in the North Atlantic Ocean and Mediterranean Sea. Sensitivity analyses were carried out to evaluate the representativeness of sampling and explore the most adequate procedure to fit the weight-length relationship (WLR). The selected model for the WLRs by stock included standardized data series (common measurement types) weighted by the inverse variability. There was little difference between annual stock-specific round weight-straight fork length relationships, with an overall difference of 6% in weight. The predicted weight by month was estimated as an additional component in the exponent of the weight-length function. The analyses of monthly variations of fish condition by stock, maturity state and geographic area reflect annual cycles of spawning and feeding behavior. We update and improve upon the biometric relationships for bluefin currently used by the International Commission for the Conservation of Atlantic Tunas, by incorporating substantially larger datasets than ever previously compiled, providing complete documentation of sources and employing robust statistical fitting. WLRs and other conversion factors estimated in this study differ from the ones used in previous bluefin stock assessments. PMID:26505476

  3. Postprandial metabolism of Pacific bluefin tuna (Thunnus orientalis).

    PubMed

    Clark, T D; Brandt, W T; Nogueira, J; Rodriguez, L E; Price, M; Farwell, C J; Block, B A

    2010-07-15

    Specific dynamic action (SDA) is defined as the energy expended during ingestion, digestion, absorption and assimilation of a meal. This study presents the first data on the SDA response of individual tunas of any species. Juvenile Pacific bluefin tunas (Thunnus orientalis; body mass 9.7-11.0 kg; N=7) were individually fed known quantities of food consisting primarily of squid and sardine (meal energy range 1680-8749 kJ, approximately 4-13% of tuna body mass). Oxygen consumption rates (M(O2)) were measured in a swim tunnel respirometer during the postprandial period at a swimming speed of 1 body length (BL) s(-1) and a water temperature of 20 degrees C. was markedly elevated above routine levels in all fish following meal consumption [routine metabolic rate (RMR)=174+/-9 mg kg(-1) h(-1)]. The peak M(O2) during the SDA process ranged from 250 to 440 mg kg(-1) h(-1) (1.5-2.3 times RMR) and was linearly related to meal energy content. The duration of the postprandial increment in M(O2) ranged from 21 h to 33 h depending upon meal energy content. Consequently, the total energy used in SDA increased linearly with meal energy and ranged from 170 kJ to 688 kJ, such that the SDA process accounted for 9.2+/-0.7% of ingested energy across all experiments. These values suggest rapid and efficient food conversion in T. orientalis in comparison with most other fishes. Implanted archival temperature tags recorded the increment in visceral temperature (T(V)) in association with SDA. M(O2) returned to routine levels at the end of the digestive period 2-3 h earlier than T(V). The qualitative patterns in M(O2) and T(V) during digestion were similar, strengthening the possibility that archival measurements of T(V) can provide new insight into the energetics and habitat utilization of free-swimming bluefin in the natural environment. Despite efficient food conversion, SDA is likely to represent a significant component of the daily energy budget of wild bluefin tunas due to a regular

  4. On the movements, aggregations and the foraging habitat of bluefin tuna (Thunnus thynnus and Thunnus orientalis)

    NASA Astrophysics Data System (ADS)

    Walli, Andreas G.

    To exploit the ocean's patchy resources, large open ocean fish species have evolved highly migratory foraging strategies. In this thesis, a synoptic study of Atlantic bluefin tuna (Thunnus thynnus) and Pacific bluefin tuna (Thunnus orientalis) and their environment was conducted to identify feeding behavior and foraging related horizontal and vertical movements, and to elucidate foraging habitat. First, electronic archival tags (n=561) were used to examine seasonal movements (1996-2005), aggregations and diving behaviors of Atlantic bluefin tuna (ABFT) to better understand their migration ecology and oceanic habitat utilization. Throughout the North Atlantic mean diving depth was significantly correlated with thermocline depth and dive behavior changed in relation to the stratification of the water column. Distribution behavior was characterized by seasonal aggregations and rapid movement phases. Throughout the North Atlantic, high residence times (167 +/- 33 days) were identified in four spatially confined regions on a seasonal scale. In these regions, mean diving depths were significantly shallower and dive frequency and internal temperature variance were significantly higher than during transit movements between the regions, suggesting foraging behavior. Residence time in high-use areas was correlated to primary productivity in northern latitudes and these areas represent critical foraging habitats with seasonally abundant prey. To be able to study feeding in wild bluefin tunas, the heat increment of feeding (HIF) in response to known quantities and caloric value of food ingested by captive individuals was evaluated. Feeding experiments were conducted using stomach and peritoneal placed archival tags in captive Pacific bluefin tuna (PBFT, n=31). Peritoneal temperature measurements indicate a significant correlation between food energy content and the duration from the start of post-grandial heat increment to the maximum thermal excess (TXmax ) in all ambient

  5. Seasonal movements, aggregations and diving behavior of Atlantic bluefin tuna (Thunnus thynnus) revealed with archival tags.

    PubMed

    Walli, Andreas; Teo, Steven L H; Boustany, Andre; Farwell, Charles J; Williams, Tom; Dewar, Heidi; Prince, Eric; Block, Barbara A

    2009-01-01

    Electronic tags were used to examine the seasonal movements, aggregations and diving behaviors of Atlantic bluefin tuna (Thunnus thynnus) to better understand their migration ecology and oceanic habitat utilization. Implantable archival tags (n = 561) were deployed in bluefin tuna from 1996 to 2005 and 106 tags were recovered. Movement paths of the fish were reconstructed using light level and sea-surface-temperature-based geolocation estimates. To quantify habitat utilization we employed a weighted kernel estimation technique that removed the biases of deployment location and track length. Throughout the North Atlantic, high residence times (167+/-33 days) were identified in four spatially confined regions on a seasonal scale. Within each region, bluefin tuna experienced distinct temperature regimes and displayed different diving behaviors. The mean diving depths within the high-use areas were significantly shallower and the dive frequency and the variance in internal temperature significantly higher than during transit movements between the high-use areas. Residence time in the more northern latitude high-use areas was significantly correlated with levels of primary productivity. The regions of aggregation are associated with areas of abundant prey and potentially represent critical foraging habitats that have seasonally abundant prey. Throughout the North Atlantic mean diving depth was significantly correlated with the depth of the thermocline, and dive behavior changed in relation to the stratification of the water column. In this study, with numerous multi-year tracks, there appear to be repeatable patterns of clear aggregation areas that potentially are changing with environmental conditions. The high concentrations of bluefin tuna in predictable locations indicate that Atlantic bluefin tuna are vulnerable to concentrated fishing efforts in the regions of foraging aggregations. PMID:19582150

  6. Seasonal Movements, Aggregations and Diving Behavior of Atlantic Bluefin Tuna (Thunnus thynnus) Revealed with Archival Tags

    PubMed Central

    Walli, Andreas; Teo, Steven L. H.; Boustany, Andre; Farwell, Charles J.; Williams, Tom; Dewar, Heidi; Prince, Eric; Block, Barbara A.

    2009-01-01

    Electronic tags were used to examine the seasonal movements, aggregations and diving behaviors of Atlantic bluefin tuna (Thunnus thynnus) to better understand their migration ecology and oceanic habitat utilization. Implantable archival tags (n = 561) were deployed in bluefin tuna from 1996 to 2005 and 106 tags were recovered. Movement paths of the fish were reconstructed using light level and sea-surface-temperature-based geolocation estimates. To quantify habitat utilization we employed a weighted kernel estimation technique that removed the biases of deployment location and track length. Throughout the North Atlantic, high residence times (167±33 days) were identified in four spatially confined regions on a seasonal scale. Within each region, bluefin tuna experienced distinct temperature regimes and displayed different diving behaviors. The mean diving depths within the high-use areas were significantly shallower and the dive frequency and the variance in internal temperature significantly higher than during transit movements between the high-use areas. Residence time in the more northern latitude high-use areas was significantly correlated with levels of primary productivity. The regions of aggregation are associated with areas of abundant prey and potentially represent critical foraging habitats that have seasonally abundant prey. Throughout the North Atlantic mean diving depth was significantly correlated with the depth of the thermocline, and dive behavior changed in relation to the stratification of the water column. In this study, with numerous multi-year tracks, there appear to be repeatable patterns of clear aggregation areas that potentially are changing with environmental conditions. The high concentrations of bluefin tuna in predictable locations indicate that Atlantic bluefin tuna are vulnerable to concentrated fishing efforts in the regions of foraging aggregations. PMID:19582150

  7. Retinal ganglion cell topography in juvenile Pacific bluefin tuna Thunnus orientalis (Temminck and Schlegel).

    PubMed

    Miyazaki, Taeko

    2014-02-01

    The retinal ganglion cell distribution, which is known to reflect fish feeding behavior, was investigated in juvenile Pacific bluefin tuna Thunnus orientalis. During the course of examination, regularly arrayed cells with a distinctive larger soma, which may be regarded as motion-sensitive cells, were found. The topographical distribution of ordinary-sized ganglion cells, which is usually utilized to estimate fish visual axis and/or visual field characteristics, showed that the highest-density area, termed the area centralis, was localized in the ventral-temporal retina. The retinal topography of ordinary-sized ganglion cells seems to reflect the bluefin tuna's foraging behavior; while cruising, cells in the area centralis may signal potential prey, such as small schooling pelagic fishes or squids, that are present in the upward-forward direction. Judging from morphological characteristics, the large ganglion cells localized in the small temporal retinal area seem to be equivalent to physiologically categorized off-center Y-cells of cat, which are stimulated by a transient dark spot in a bright visual field. It was inferred that presumed large off-center cells in the temporal retina detect movements of agile prey animals escaping from bluefin tuna as a silhouette against environmental light. PMID:23775518

  8. Changes in the distribution of atlantic bluefin tuna (Thunnus thynnus) in the Gulf of Maine 1979-2005.

    PubMed

    Golet, Walter J; Galuardi, Benjamin; Cooper, Andrew B; Lutcavage, Molly E

    2013-01-01

    The Gulf of Maine, NW Atlantic Ocean, is a productive, seasonal foraging ground for Atlantic bluefin tuna (Thunnus thynnus), but commercial landings of adult size classes were up to 40% below the allocated total allowable catch between 2004 to 2008 for the rod and reel, harpoon, and purse seine categories in the Gulf of Maine. Reduction in Atlantic bluefin tuna catches in the Gulf of Maine could represent a decline in spawning stock biomass, but given wide-ranging, complex migration patterns, and high energetic requirements, an alternative hypothesis is that their dispersal patterns shifted to regions with higher prey abundance or profitability, reducing availability to U.S. fishing fleets. This study fit generalized linear models to Atlantic bluefin tuna landings data collected from fishermen's logbooks (1979-2005) as well as the distances between bluefin tuna schools and Atlantic herring (Clupeaharengus), a primary prey species, to test alternative hypotheses for observed shifts in Atlantic bluefin tuna availability in the Gulf of Maine. For the bluefin model, landings varied by day of year, latitude and longitude. The effect of latitude differed by day of year and the effect of longitude differed by year. The distances between Atlantic bluefin tuna schools and Atlantic herring schools were significantly smaller (p<0.05) than would be expected from a randomly distributed population. A time series of average bluefin tuna school positions was positively correlated with the average number of herring captured per tow on Georges Bank in spring and autumn surveys respectively (p<0.01, r(2)=0.24, p<0.01, r(2)=0.42). Fishermen's logbooks contributed novel spatial and temporal information towards testing these hypotheses for the bluefin tuna fishery. PMID:24069420

  9. Changes in the Distribution of Atlantic Bluefin Tuna (Thunnus thynnus) in the Gulf of Maine 1979-2005

    PubMed Central

    Golet, Walter J.; Galuardi, Benjamin; Cooper, Andrew B.; Lutcavage, Molly E.

    2013-01-01

    The Gulf of Maine, NW Atlantic Ocean, is a productive, seasonal foraging ground for Atlantic bluefin tuna (Thunnus thynnus), but commercial landings of adult size classes were up to 40% below the allocated total allowable catch between 2004 to 2008 for the rod and reel, harpoon, and purse seine categories in the Gulf of Maine. Reduction in Atlantic bluefin tuna catches in the Gulf of Maine could represent a decline in spawning stock biomass, but given wide-ranging, complex migration patterns, and high energetic requirements, an alternative hypothesis is that their dispersal patterns shifted to regions with higher prey abundance or profitability, reducing availability to U.S. fishing fleets. This study fit generalized linear models to Atlantic bluefin tuna landings data collected from fishermen’s logbooks (1979-2005) as well as the distances between bluefin tuna schools and Atlantic herring (Clupeaharengus), a primary prey species, to test alternative hypotheses for observed shifts in Atlantic bluefin tuna availability in the Gulf of Maine. For the bluefin model, landings varied by day of year, latitude and longitude. The effect of latitude differed by day of year and the effect of longitude differed by year. The distances between Atlantic bluefin tuna schools and Atlantic herring schools were significantly smaller (p<0.05) than would be expected from a randomly distributed population. A time series of average bluefin tuna school positions was positively correlated with the average number of herring captured per tow on Georges Bank in spring and autumn surveys respectively (p<0.01, r2=0.24, p<0.01, r2=0.42). Fishermen’s logbooks contributed novel spatial and temporal information towards testing these hypotheses for the bluefin tuna fishery. PMID:24069420

  10. Characterization of two tropomyosin isoforms from the fast skeletal muscle of bluefin tuna Thunnus thynnusorientalis.

    PubMed

    Ochiai, Yoshihiro; Ozawa, Hideo; Huang, Ming-Chih; Watabe, Shugo

    2010-10-15

    Fast skeletal muscle tropomyosin (TM) of tunas is composed of nearly equimolar amount of two isoforms designated alpha-TM and beta-TM expediently based on their migration behavior in SDS-PAGE, whereas corresponding TMs from the other fish species are homogenous (alpha-type). The presence of beta-TM is thus specific to tunas so far. The amino acid sequence of beta-TM from bluefin tuna Thunnus thynnus orientalis, which has not been revealed to date unlike alpha-TM, was successfully obtained in this study by cDNA cloning. The coding region of beta-TM cDNA comprised of an open reading frame of 855bp encoding 284 amino acid residues, like most of the TMs. Unexpectedly, the sequence of beta-TM showed high similarity to those of other vertebrate alpha-type TMs including tuna alpha-TM. Phylogenetic analysis also showed that beta-TM has the closest relationship with alpha-TM of tuna. This fact was quite unlike the relation of mammalian alpha- and beta-TMs. Based on the distribution of amino acid substitutions, it was suggested that tuna TM isoforms are the products of different genes. By thermodynamic analysis of native and reconstituted TMs, it was demonstrated that beta-TM is less thermostable than alpha-TM. Proteolytic digestion also supported the lower stability of the former. PMID:20646991

  11. Electronic tagging of Atlantic bluefin tuna (Thunnus thynnus, L.) reveals habitat use and behaviors in the Mediterranean Sea.

    PubMed

    Cermeño, Pablo; Quílez-Badia, Gemma; Ospina-Alvarez, Andrés; Sainz-Trápaga, Susana; Boustany, Andre M; Seitz, Andy C; Tudela, Sergi; Block, Barbara A

    2015-01-01

    We analyzed the movements of Atlantic tuna (Thunnus thynnus L.) in the Mediterranean Sea using data from 2 archival tags and 37 pop-up satellite archival tags (PAT). Bluefin tuna ranging in size from 12 to 248 kg were tagged on board recreational boats in the western Mediterranean and the Adriatic Sea between May and September during two different periods (2000 to 2001 and 2008 to 2012). Although tuna migrations between the Mediterranean Sea and the Atlantic Ocean have been well reported, our results indicate that part of the bluefin tuna population remains in the Mediterranean basin for much of the year, revealing a more complex population structure. In this study we demonstrate links between the western Mediterranean, the Adriatic and the Gulf of Sidra (Libya) using over 4336 recorded days of location and behavior data from tagged bluefin tuna with a maximum track length of 394 days. We described the oceanographic preferences and horizontal behaviors during the spawning season for 4 adult bluefin tuna. We also analyzed the time series data that reveals the vertical behavior of one pop-up satellite tag recovered, which was attached to a 43.9 kg tuna. This fish displayed a unique diving pattern within 16 days of the spawning season, suggesting a use of the thermocline as a thermoregulatory mechanism compatible with spawning. The results obtained hereby confirm that the Mediterranean is clearly an important habitat for this species, not only as spawning ground, but also as an overwintering foraging ground. PMID:25671316

  12. Electronic Tagging of Atlantic Bluefin Tuna (Thunnus thynnus, L.) Reveals Habitat Use and Behaviors in the Mediterranean Sea

    PubMed Central

    Cermeño, Pablo; Quílez-Badia, Gemma; Ospina-Alvarez, Andrés; Sainz-Trápaga, Susana; Boustany, Andre M.; Seitz, Andy C.; Tudela, Sergi; Block, Barbara A.

    2015-01-01

    We analyzed the movements of Atlantic tuna (Thunnus thynnus L.) in the Mediterranean Sea using data from 2 archival tags and 37 pop-up satellite archival tags (PAT). Bluefin tuna ranging in size from 12 to 248 kg were tagged on board recreational boats in the western Mediterranean and the Adriatic Sea between May and September during two different periods (2000 to 2001 and 2008 to 2012). Although tuna migrations between the Mediterranean Sea and the Atlantic Ocean have been well reported, our results indicate that part of the bluefin tuna population remains in the Mediterranean basin for much of the year, revealing a more complex population structure. In this study we demonstrate links between the western Mediterranean, the Adriatic and the Gulf of Sidra (Libya) using over 4336 recorded days of location and behavior data from tagged bluefin tuna with a maximum track length of 394 days. We described the oceanographic preferences and horizontal behaviors during the spawning season for 4 adult bluefin tuna. We also analyzed the time series data that reveals the vertical behavior of one pop-up satellite tag recovered, which was attached to a 43.9 kg tuna. This fish displayed a unique diving pattern within 16 days of the spawning season, suggesting a use of the thermocline as a thermoregulatory mechanism compatible with spawning. The results obtained hereby confirm that the Mediterranean is clearly an important habitat for this species, not only as spawning ground, but also as an overwintering foraging ground. PMID:25671316

  13. Mercury in Pacific bluefin tuna (Thunnus orientalis):bioaccumulation and trans-Pacific Ocean migration

    USGS Publications Warehouse

    Colman, John A.; Nogueira, Jacob I.; Pancorbo, Oscar C.; Batdorf, Carol A.; Block, Barbara A.

    2015-01-01

    Pacific bluefin tuna (Thunnus orientalis) have the largest home range of any tuna species and are well known for the capacity to make transoceanic migrations. We report the measurement of mercury (Hg) concentrations in wild Pacific bluefin tuna (PBFT), the first reported with known size-of-fish and capture location. The results indicate juvenile PBFT that are recently arrived in the California Current from the western Pacific Ocean have significantly higher Hg concentrations in white muscle (0.51 ug/g wet mass, wm) than PBFT of longer California Current residency (0.41 ug/g wm). These new arrivals are also higher in Hg concentration than PBFT in farm pens (0.43 ug/g wm) that were captured on arrival in the California Current and raised in pens on locally derived feed. Analysis by direct Hg analyzer and attention to Hg by tissue type and location on the fish allowed precise comparisons of mercury among wild and captive fish populations. Analysis of migration and nearshore residency, determined through extensive archival tagging, bioaccumulation models, trophic investigations, and potential coastal sources of methylmercury, indicates Hg bioaccumulation is likely greater for PBFT juvenile habitats in the western Pacific Ocean (East China Sea, Yellow Sea) than in the eastern Pacific Ocean (California Current). Differential bioaccumulation may be a trophic effect or reflect methylmercury availability, with potential sources for coastal China (large hypoxic continental shelf receiving discharge of three large rivers, and island-arc volcanism) different from those for coastal Baja California (small continental shelf, no large rivers, spreading-center volcanism).

  14. Movements of pacific bluefin tuna ( Thunnus orientalis) in the Eastern North Pacific revealed with archival tags

    NASA Astrophysics Data System (ADS)

    Boustany, Andre M.; Matteson, Robyn; Castleton, Michael; Farwell, Charles; Block, Barbara A.

    2010-07-01

    In this study, 253 Pacific bluefin tuna were archivally tagged off the coast of California, USA and Baja California, Mexico between August 2002 and August 2005. One hundred and fifty-seven fish were recaptured and 143 datasets were obtained and analyzed, yielding electronic tag datasets of up to 1203 days. Mean days at large for the 143 fish was 359 ± 248 (SD) days. A total of 38,012 geolocations were calculated from light-based longitude and SST-based latitude estimates, allowing us to examine the seasonal movement of juvenile bluefin tuna off the west coast of North America. Electronic tagged bluefin tuna showed repeatable seasonal movements along the west coast of North America. Bluefin tuna were found farthest south in the spring when they were located off southern Baja California, Mexico and farthest north in the fall when fish were found predominately off central and northern California. Fish showed latitudinal movement patterns that were correlated with peaks in coastal upwelling-induced primary productivity. Interannual variation in the locality of these productivity peaks was linked with a corresponding movement in the distribution of tagged fish. Overall geographical area occupied by tagged bluefin varied with primary productivity, with fish being more tightly clustered in areas of high productivity and more dispersed in regions of low productivity. In the spring through fall, bluefin tuna were located in areas with the highest levels of primary productivity available in the California Current ecosystem. However, in the winter months, tagged bluefin tuna were found in areas with lower productivity compared to other regions along the coast at that time of year suggesting that during the winter, bluefin tuna are feeding on aggregations of pelagic red crabs, sardines and anchovies that preferentially spawn in areas of reduced coastal upwelling.

  15. Near resonance acoustic scattering from organized schools of juvenile Atlantic bluefin tuna (Thunnus thynnus).

    PubMed

    Weber, Thomas C; Lutcavage, Molly E; Schroth-Miller, Madeline L

    2013-06-01

    Schools of Atlantic bluefin tuna (Thunnus thynnus) can exhibit highly organized spatial structure within the school. This structure was quantified for dome shaped schools using both aerial imagery collected from a commercial spotter plane and 400 kHz multibeam echo sounder data collected on a fishing vessel in 2009 in Cape Cod Bay, MA. Observations from one school, containing an estimated 263 fish within an approximately ellipsoidal volume of 1900 m(3), were used to seed an acoustic model that estimated the school target strength at frequencies between 10 and 2000 Hz. The fish's swimbladder resonance was estimated to occur at approximately 50 Hz. The acoustic model examined single and multiple scattering solutions and also a completely incoherent summation of scattering responses from the fish. Three levels of structure within the school were examined, starting with fish locations that were constrained by the school boundaries but placed according to a Poisson process, then incorporating a constraint on the distance to the nearest neighbor, and finally adding a constraint on the bearing to the nearest neighbor. Results suggest that both multiple scattering and spatial organization within the school should be considered when estimating the target strength of schools similar to the ones considered here. PMID:23742334

  16. Amino acid isotope incorporation and enrichment factors in Pacific bluefin tuna, Thunnus orientalis.

    PubMed

    Bradley, Christina J; Madigan, Daniel J; Block, Barbara A; Popp, Brian N

    2014-01-01

    Compound specific isotopic analysis (CSIA) of amino acids has received increasing attention in ecological studies in recent years due to its ability to evaluate trophic positions and elucidate baseline nutrient sources. However, the incorporation rates of individual amino acids into protein and specific trophic discrimination factors (TDFs) are largely unknown, limiting the application of CSIA to trophic studies. We determined nitrogen turnover rates of individual amino acids from a long-term (up to 1054 days) laboratory experiment using captive Pacific bluefin tuna, Thunnus orientalis (PBFT), a large endothermic pelagic fish fed a controlled diet. Small PBFT (white muscle δ(15)N∼11.5‰) were collected in San Diego, CA and transported to the Tuna Research and Conservation Center (TRCC) where they were fed a controlled diet with high δ(15)N values relative to PBFT white muscle (diet δ(15)N∼13.9‰). Half-lives of trophic and source amino acids ranged from 28.6 to 305.4 days and 67.5 to 136.2 days, respectively. The TDF for the weighted mean values of amino acids was 3.0 ‰, ranging from 2.2 to 15.8 ‰ for individual combinations of 6 trophic and 5 source amino acids. Changes in the δ(15)N values of amino acids across trophic levels are the underlying drivers of the trophic (15)N enrichment. Nearly all amino acid δ(15)N values in this experiment changed exponentially and could be described by a single compartment model. Significant differences in the rate of (15)N incorporation were found for source and trophic amino acids both within and between these groups. Varying half-lives of individual amino acids can be applied to migratory organisms as isotopic clocks, determining the length of time an individual has spent in a new environment. These results greatly enhance the ability to interpret compound specific isotope analyses in trophic studies. PMID:24465724

  17. Amino Acid Isotope Incorporation and Enrichment Factors in Pacific Bluefin Tuna, Thunnus orientalis

    PubMed Central

    Bradley, Christina J.; Madigan, Daniel J.; Block, Barbara A.; Popp, Brian N.

    2014-01-01

    Compound specific isotopic analysis (CSIA) of amino acids has received increasing attention in ecological studies in recent years due to its ability to evaluate trophic positions and elucidate baseline nutrient sources. However, the incorporation rates of individual amino acids into protein and specific trophic discrimination factors (TDFs) are largely unknown, limiting the application of CSIA to trophic studies. We determined nitrogen turnover rates of individual amino acids from a long-term (up to 1054 days) laboratory experiment using captive Pacific bluefin tuna, Thunnus orientalis (PBFT), a large endothermic pelagic fish fed a controlled diet. Small PBFT (white muscle δ15N∼11.5‰) were collected in San Diego, CA and transported to the Tuna Research and Conservation Center (TRCC) where they were fed a controlled diet with high δ15N values relative to PBFT white muscle (diet δ15N∼13.9‰). Half-lives of trophic and source amino acids ranged from 28.6 to 305.4 days and 67.5 to 136.2 days, respectively. The TDF for the weighted mean values of amino acids was 3.0 ‰, ranging from 2.2 to 15.8 ‰ for individual combinations of 6 trophic and 5 source amino acids. Changes in the δ15N values of amino acids across trophic levels are the underlying drivers of the trophic 15N enrichment. Nearly all amino acid δ15N values in this experiment changed exponentially and could be described by a single compartment model. Significant differences in the rate of 15N incorporation were found for source and trophic amino acids both within and between these groups. Varying half-lives of individual amino acids can be applied to migratory organisms as isotopic clocks, determining the length of time an individual has spent in a new environment. These results greatly enhance the ability to interpret compound specific isotope analyses in trophic studies. PMID:24465724

  18. Discovery of a spawning ground reveals diverse migration strategies in Atlantic bluefin tuna (Thunnus thynnus).

    PubMed

    Richardson, David E; Marancik, Katrin E; Guyon, Jeffrey R; Lutcavage, Molly E; Galuardi, Benjamin; Lam, Chi Hin; Walsh, Harvey J; Wildes, Sharon; Yates, Douglas A; Hare, Jonathan A

    2016-03-22

    Atlantic bluefin tuna are a symbol of both the conflict between preservationist and utilitarian views of top ocean predators, and the struggle to reach international consensus on the management of migratory species. Currently, Atlantic bluefin tuna are managed as an early-maturing eastern stock, which spawns in the Mediterranean Sea, and a late-maturing western stock, which spawns in the Gulf of Mexico. However, electronic tagging studies show that many bluefin tuna, assumed to be of a mature size, do not visit either spawning ground during the spawning season. Whether these fish are spawning in an alternate location, skip-spawning, or not spawning until an older age affects how vulnerable this species is to anthropogenic stressors including exploitation. We use larval collections to demonstrate a bluefin tuna spawning ground in the Slope Sea, between the Gulf Stream and northeast United States continental shelf. We contend that western Atlantic bluefin tuna have a differential spawning migration, with larger individuals spawning in the Gulf of Mexico, and smaller individuals spawning in the Slope Sea. The current life history model, which assumes only Gulf of Mexico spawning, overestimates age at maturity for the western stock. Furthermore, individual tuna occupy both the Slope Sea and Mediterranean Sea in separate years, contrary to the prevailing view that individuals exhibit complete spawning-site fidelity. Overall, this complexity of spawning migrations questions whether there is complete independence in the dynamics of eastern and western Atlantic bluefin tuna and leads to lower estimates of the vulnerability of this species to exploitation and other anthropogenic stressors. PMID:26951668

  19. Discovery of a spawning ground reveals diverse migration strategies in Atlantic bluefin tuna (Thunnus thynnus)

    PubMed Central

    Richardson, David E.; Marancik, Katrin E.; Guyon, Jeffrey R.; Lutcavage, Molly E.; Galuardi, Benjamin; Lam, Chi Hin; Walsh, Harvey J.; Wildes, Sharon; Yates, Douglas A.; Hare, Jonathan A.

    2016-01-01

    Atlantic bluefin tuna are a symbol of both the conflict between preservationist and utilitarian views of top ocean predators, and the struggle to reach international consensus on the management of migratory species. Currently, Atlantic bluefin tuna are managed as an early-maturing eastern stock, which spawns in the Mediterranean Sea, and a late-maturing western stock, which spawns in the Gulf of Mexico. However, electronic tagging studies show that many bluefin tuna, assumed to be of a mature size, do not visit either spawning ground during the spawning season. Whether these fish are spawning in an alternate location, skip-spawning, or not spawning until an older age affects how vulnerable this species is to anthropogenic stressors including exploitation. We use larval collections to demonstrate a bluefin tuna spawning ground in the Slope Sea, between the Gulf Stream and northeast United States continental shelf. We contend that western Atlantic bluefin tuna have a differential spawning migration, with larger individuals spawning in the Gulf of Mexico, and smaller individuals spawning in the Slope Sea. The current life history model, which assumes only Gulf of Mexico spawning, overestimates age at maturity for the western stock. Furthermore, individual tuna occupy both the Slope Sea and Mediterranean Sea in separate years, contrary to the prevailing view that individuals exhibit complete spawning-site fidelity. Overall, this complexity of spawning migrations questions whether there is complete independence in the dynamics of eastern and western Atlantic bluefin tuna and leads to lower estimates of the vulnerability of this species to exploitation and other anthropogenic stressors. PMID:26951668

  20. Expression of vitellogenin receptor gene in the ovary of wild and captive Atlantic bluefin tuna (Thunnus thynnus).

    PubMed

    Pousis, C; Santamaria, N; Zupa, R; De Giorgi, C; Mylonas, C C; Bridges, C R; de la Gándara, F; Vassallo-Agius, R; Bello, G; Corriero, A

    2012-05-01

    The cDNA sequences of vitellogenin receptor proteins (VgR(+) and VgR(-)), containing or lacking the O-linked sugar domain, were determined in Atlantic bluefin tuna (Thunnus thynnus L.). VgR(-) gene expression in the ovary was compared in captive-reared and wild Atlantic bluefin tuna during the reproductive cycle. Gonad samples from adult fish were sampled from 2008 to 2010 from stocks reared in captivity at different commercial fattening operations in the Mediterranean Sea and from wild individuals caught either by traditional tuna traps during their migration towards the spawning grounds in the Mediterranean Sea or by the long-line artisanal fishery. In addition, juvenile male and female Atlantic bluefin tuna were sampled from a farming facility, to obtain baseline information and pre-adulthood amounts of VgR(-). The total length of VgR(+) cDNA was 4006 nucleotides (nt) and that of VgR(-) was 3946 nt. Relative amounts of VgR(-) were greater in juvenile females and in those adults having only previtellogenic oocytes (119 ± 55 and 146 ± 26 folds more than juvenile males, respectively). Amounts of VgR(-) were less in individuals with yolked oocytes (ripening stage, May-June) and increased after spawning in July (92 ± 20 and 113 ± 13 folds more than juvenile males in ripening and post-spawning fish, respectively). These data suggest that regulation of VgR(-) is not under oestrogen control. During the ripening period, greater VgR(-) gene expression was observed in wild fish than in fish reared in captivity, possibly because of (a) differences in water temperature exposure and/or energy storage, and/or (b) an inadequate diet in reared Atlantic bluefin tuna. PMID:22541277

  1. Detection rate of diarrhoea-causing Kudoa hexapunctata in Pacific bluefin tuna Thunnus orientalis from Japanese waters.

    PubMed

    Suzuki, Jun; Murata, Rie; Yokoyama, Hiroshi; Sadamasu, Kenji; Kai, Akemi

    2015-02-01

    Diffuse outbreaks of food poisoning with unknown aetiologies leading to diarrhoea and vomiting within a short time after ingesting flatfish (Paralichthys olivaceus), tuna (Thunnus spp.), or amberjack (Seriola dumerili) have occurred nationwide in Japan, including the Tokyo metropolitan area. In this study, we surveyed the detection rates of kudoid parasites in 12 tuna samples that caused clinical diarrhoea from 2009 to 2012; we assessed 104 samples of whole juvenile Pacific bluefin tuna (PBT, Thunnus orientalis) and 153 block samples of other tuna distributed in the Tokyo Metropolitan Central Wholesale Market. The survey revealed that more than 70% of clinical diarrhoea cases due to tuna ingestion occurred between June and September, and Kudoa hexapunctata were detected in 9 of 12 tuna samples associated with clinical diarrhoea cases. The numbers of spores and 18S ribosomal DNA (rDNA) copies per gram of fish in 8 of 9 samples were more than 1×10(6) spores and 1×10(9) copies, respectively. Market research revealed that the K. hexapunctata-positive rate in juvenile PBT from Japanese waters was 64.4% (67/104) but that in adult PBT was 10.4% (7/67). The numbers of K. hexapunctata 18S rDNA copies in 64.5% (20/31) samples and 72.7% (16/22) of <5kg fish samples collected between May and July were more than 1×10(9)copies/g. On the other hand, kudoid parasites were not detected from 73 tuna samples except for a single sample of Thunnus albacares. Cell monolayer permeability assays performed to examine the toxicity of K. hexapunctata against Caco-2 cells revealed that the transepithelial electrical resistance (TER) in 5×10(7)K. hexapunctata spores decreased by 80% within 2-4h. In conclusion, K. hexapunctata was commonly detected in juvenile PBT from Japanese waters and are a likely cause of the diarrhoea outbreaks. PMID:25461601

  2. Atlantic bluefin tuna (Thunnus thynnus) population dynamics delineated by organochlorine tracers.

    PubMed

    Dickhut, Rebecca M; Deshpande, Ashok D; Cincinelli, Alessandra; Cochran, Michele A; Corsolini, Simonetta; Brill, Richard W; Secor, David H; Graves, John E

    2009-11-15

    Atlantic bluefin tuna (ABFT) are highly valued and heavily exploited, and critical uncertainties regarding their population structure hinder effective management. Evidence supports the existence of two breeding populations of ABFT; a western population in the Gulf of Mexico and an eastern population in the Mediterranean Sea; both of which migrate and mix in the North Atlantic. Conventional tagging studies suggest low rates of trans-Atlantic migrations; however, electronic tagging and stable isotopes in otoliths indicate stock mixing up to 57% between management zones delineated by 45 degrees W longitude. Here we show that organochlorine pesticides and polychlorinated biphenyls (PCBs) can be used as tracers of bluefin tuna foraging grounds in the North Atlantic and confirm that stock mixing of juvenile tuna within the U.S. Mid Atlantic Bight is indeed high (33-83% eastern origin), and is likely spatially and temporally variable. We further demonstrate that >10% of the Mediterranean population is migratory, that young bluefin tuna migrate from the Mediterranean to western Atlantic foraging grounds as early as age 1, and then return to the Mediterranean Sea as young as age 5, presumably to breed. The tracer method described here provides a novel means for distinguishing bluefin tuna populations and ontogenetic shifts in migration in the North Atlantic. PMID:20028046

  3. Spawning Dynamics and Size Related Trends in Reproductive Parameters of Southern Bluefin Tuna, Thunnus maccoyii

    PubMed Central

    Farley, Jessica. H.; Davis, Tim L. O.; Bravington, Mark V.; Andamari, Retno; Davies, Campbell R.

    2015-01-01

    Knowledge of spawning behaviour and fecundity of fish is important for estimating the reproductive potential of a stock and for constructing appropriate statistical models for assessing sustainable catch levels. Estimates of length-based reproductive parameters are particularly important for determining potential annual fecundity as a function of fish size, but they are often difficult to estimate reliably. Here we provide new information on the reproductive dynamics of southern bluefin tuna (SBT) Thunnus maccoyii through the analysis of fish size and ovary histology collected on the spawning ground in 1993–1995 and 1999–2002. These are used to refine previous parameter estimates of spawning dynamics and investigate size related trends in these parameters. Our results suggest that the small SBT tend to arrive on the spawning ground slightly later and depart earlier in the spawning season relative to large fish. All females were mature and the majority were classed as spawning capable (actively spawning or non-spawning) with a very small proportion classed as regressing. The fraction of females spawning per day decreased with fish size, but once females start a spawning episode, they spawned daily irrespective of size. Mean batch fecundity was estimated directly at 6.5 million oocytes. Analysis of ovary histology and ovary weight data indicated that relative batch fecundity, and the duration of spawning and non-spawning episodes, increased with fish size. These reproductive parameter estimates could be used with estimates of residency time on the spawning ground as a function of fish size (if known) and demographic data for the spawning population to provide a time series of relative annual fecundity for SBT. PMID:25993276

  4. Spawning behaviour and post-spawning migration patterns of atlantic bluefin tuna (Thunnus thynnus) ascertained from satellite archival tags.

    PubMed

    Aranda, Guillermo; Abascal, Francisco Javier; Varela, José Luis; Medina, Antonio

    2013-01-01

    Spawning behaviour of Atlantic bluefin tuna (Thunnus thynnus) was investigated using electronic satellite tags deployed in the western Mediterranean spawning ground, around the Balearic Islands (years 2009-2011). All the fish were tagged underwater and released within schools. In general, the fish tagged in the same year/school displayed common migratory trends. Following extended residency around the Balearic Islands, most tagged tuna crossed the Strait of Gibraltar heading for the North Atlantic. Discrepancies between the migratory tracks reconstructed from this and previous electronic tagging studies suggest that the bluefin tuna Mediterranean population may comprise distinct units exhibiting differing migratory behaviours. The diving behaviour varied between oceanic regions throughout the migratory pathways, the shallowest distribution taking place in the spawning ground and the deepest at the Strait of Gibraltar. A unique diving pattern was found on the majority of nights while the fish stayed at the spawning ground; it consisted of frequent and brief oscillatory movements up and down through the mixed layer, resulting in thermal profiles characterized by oscillations about the thermocline. Such a pattern is believed to reflect recent courtship and spawning activity. Reproductive parameters inferred from the analysis of vertical profiles are consistent with those estimated in previous studies based on biological samples. PMID:24098502

  5. Spawning Behaviour and Post-Spawning Migration Patterns of Atlantic Bluefin Tuna (Thunnus thynnus) Ascertained from Satellite Archival Tags

    PubMed Central

    Aranda, Guillermo; Abascal, Francisco Javier; Varela, José Luis; Medina, Antonio

    2013-01-01

    Spawning behaviour of Atlantic bluefin tuna (Thunnus thynnus) was investigated using electronic satellite tags deployed in the western Mediterranean spawning ground, around the Balearic Islands (years 2009-2011). All the fish were tagged underwater and released within schools. In general, the fish tagged in the same year/school displayed common migratory trends. Following extended residency around the Balearic Islands, most tagged tuna crossed the Strait of Gibraltar heading for the North Atlantic. Discrepancies between the migratory tracks reconstructed from this and previous electronic tagging studies suggest that the bluefin tuna Mediterranean population may comprise distinct units exhibiting differing migratory behaviours. The diving behaviour varied between oceanic regions throughout the migratory pathways, the shallowest distribution taking place in the spawning ground and the deepest at the Strait of Gibraltar. A unique diving pattern was found on the majority of nights while the fish stayed at the spawning ground; it consisted of frequent and brief oscillatory movements up and down through the mixed layer, resulting in thermal profiles characterized by oscillations about the thermocline. Such a pattern is believed to reflect recent courtship and spawning activity. Reproductive parameters inferred from the analysis of vertical profiles are consistent with those estimated in previous studies based on biological samples. PMID:24098502

  6. A histological investigation of the occurrence of non-reproductive female bluefin tuna Thunnus thynnus in the Mediterranean Sea.

    PubMed

    Zupa, R; Corriero, A; Deflorio, M; Santamaria, N; Spedicato, D; Marano, C; Losurdo, M; Bridges, C R; De Metrio, G

    2009-10-01

    The presence of non-reproductive Atlantic bluefin tuna Thunnus thynnus females in the Mediterranean Sea was investigated through histological analysis of the gonads. Three hundred and twenty-six ovary samples were collected from adults captured at different locations in the Mediterranean Sea during the reproductive seasons between 1998 and 2008. Only three specimens were considered to be in a non-reproductive state: two of them were in a reabsorbing state showing ovaries with early vitellogenic oocytes and extensive alpha and beta atresia of vitellogenic follicles; the third showed gonads with perinucleolar oocytes and was considered to be in a resting state. The low occurrence of non-reproductive individuals found in this study makes it unlikely that non-reproductive individuals aggregate with reproductive ones during their migration towards spawning grounds. Further research is suggested in order to investigate the potential presence of non-reproductive individuals on non-spawning grounds during the reproductive season. PMID:20738610

  7. Tissue Turnover Rates and Isotopic Trophic Discrimination Factors in the Endothermic Teleost, Pacific Bluefin Tuna (Thunnus orientalis)

    PubMed Central

    Madigan, Daniel J.; Litvin, Steven Y.; Popp, Brian N.; Carlisle, Aaron B.; Farwell, Charles J.; Block, Barbara A.

    2012-01-01

    Stable isotope analysis (SIA) of highly migratory marine pelagic animals can improve understanding of their migratory patterns and trophic ecology. However, accurate interpretation of isotopic analyses relies on knowledge of isotope turnover rates and tissue-diet isotope discrimination factors. Laboratory-derived turnover rates and discrimination factors have been difficult to obtain due to the challenges of maintaining these species in captivity. We conducted a study to determine tissue- (white muscle and liver) and isotope- (nitrogen and carbon) specific turnover rates and trophic discrimination factors (TDFs) using archived tissues from captive Pacific bluefin tuna (PBFT), Thunnus orientalis, 1–2914 days after a diet shift in captivity. Half-life values for 15N turnover in white muscle and liver were 167 and 86 days, and for 13C were 255 and 162 days, respectively. TDFs for white muscle and liver were 1.9 and 1.1‰ for δ15N and 1.8 and 1.2‰ for δ13C, respectively. Our results demonstrate that turnover of 15N and 13C in bluefin tuna tissues is well described by a single compartment first-order kinetics model. We report variability in turnover rates between tissue types and their isotope dynamics, and hypothesize that metabolic processes play a large role in turnover of nitrogen and carbon in PBFT white muscle and liver tissues. 15N in white muscle tissue showed the most predictable change with diet over time, suggesting that white muscle δ15N data may provide the most reliable inferences for diet and migration studies using stable isotopes in wild fish. These results allow more accurate interpretation of field data and dramatically improve our ability to use stable isotope data from wild tunas to better understand their migration patterns and trophic ecology. PMID:23145128

  8. Tissue turnover rates and isotopic trophic discrimination factors in the endothermic teleost, pacific bluefin tuna (Thunnus orientalis).

    PubMed

    Madigan, Daniel J; Litvin, Steven Y; Popp, Brian N; Carlisle, Aaron B; Farwell, Charles J; Block, Barbara A

    2012-01-01

    Stable isotope analysis (SIA) of highly migratory marine pelagic animals can improve understanding of their migratory patterns and trophic ecology. However, accurate interpretation of isotopic analyses relies on knowledge of isotope turnover rates and tissue-diet isotope discrimination factors. Laboratory-derived turnover rates and discrimination factors have been difficult to obtain due to the challenges of maintaining these species in captivity. We conducted a study to determine tissue- (white muscle and liver) and isotope- (nitrogen and carbon) specific turnover rates and trophic discrimination factors (TDFs) using archived tissues from captive Pacific bluefin tuna (PBFT), Thunnus orientalis, 1-2914 days after a diet shift in captivity. Half-life values for (15)N turnover in white muscle and liver were 167 and 86 days, and for (13)C were 255 and 162 days, respectively. TDFs for white muscle and liver were 1.9 and 1.1‰ for δ(15)N and 1.8 and 1.2‰ for δ(13)C, respectively. Our results demonstrate that turnover of (15)N and (13)C in bluefin tuna tissues is well described by a single compartment first-order kinetics model. We report variability in turnover rates between tissue types and their isotope dynamics, and hypothesize that metabolic processes play a large role in turnover of nitrogen and carbon in PBFT white muscle and liver tissues. (15)N in white muscle tissue showed the most predictable change with diet over time, suggesting that white muscle δ(15)N data may provide the most reliable inferences for diet and migration studies using stable isotopes in wild fish. These results allow more accurate interpretation of field data and dramatically improve our ability to use stable isotope data from wild tunas to better understand their migration patterns and trophic ecology. PMID:23145128

  9. Effect of temperature acclimation on red blood cell oxygen affinity in Pacific bluefin tuna (Thunnus orientalis) and yellowfin tuna (Thunnus albacares).

    PubMed

    Lilly, Laura E; Bonaventura, Joseph; Lipnick, Michael S; Block, Barbara A

    2015-03-01

    Hemoglobin-oxygen (Hb-O2) binding properties are central to aerobic physiology, and must be optimized for an animal's aerobic requirements and environmental conditions, both of which can vary widely with seasonal changes or acutely with diving. In the case of tunas, the matter is further complicated by large regional temperature differences between tissues within the same animal. This study investigates the effects of thermal acclimation on red blood cell Hb-O2 binding in Pacific bluefin tuna (T. orientalis) and yellowfin tuna (T. albacares) maintained in captive tanks at acclimation temperatures of 17°, 20° and 24 °C. Oxygen binding properties of acclimated tuna isolated red blood cells were examined under varying experimental temperatures (15°-35 °C) and CO2 levels (0%, 0.5% and 1.5%). Results for Pacific bluefin tuna produced temperature-independence at 17 °C- and 20 °C-acclimation temperatures and significant reverse temperature-dependence at 24 °C-acclimation in the absence of CO2, with instances of reverse temperature-dependence in 17 °C- and 24 °C-acclimations at 0.5% and 1.5% CO2. In contrast, yellowfin tuna produced normal temperature-dependence at each acclimation temperature at 0% CO2, temperature-independence at 0.5% and 1.5% CO2, and significant reverse temperature-dependence at 17 °C-acclimation and 0.5% CO2. Thermal acclimation of Pacific bluefin tuna increased O2 binding affinity of the 17 °C-acclimation group, and produced a significantly steeper oxygen equilibrium curve slope (nH) at 24 °C-acclimation compared to the other acclimation temperatures. We discuss the potential implications of these findings below. PMID:25434601

  10. Brain morphology and immunohistochemical localization of the gonadotropin-releasing hormone in the bluefin tuna, Thunnus thynnus.

    PubMed

    Palmieri, G; Acone, F; Desantis, S; Corriero, A; Ventriglia, G; Addis, P; Genovese, S; Aprea, A; Spedicato, D; Losurdo, M; Deflorio, M; Di Summa, A; De Metrio, G

    2008-01-01

    The present study was focused on the morphology of the diencephalic nuclei (likely involved in reproductive functions) as well as on the distribution of GnRH (gonadotropin-releasing hormone) in the rhinencephalon, telencephalon and the diencephalon of the brain of bluefin tuna (Thunnus thynnus) by means of immunohistochemistry. Bluefin tuna has an encephalization quotient (QE) similar to that of other large pelagic fish. Its brain exhibits well-developed optic tecta and corpus cerebelli. The diencephalic neuron cell bodies involved in reproductive functions are grouped in two main nuclei: the nucleus preopticus-periventricularis and the nucleus lateralis tuberis. The nucleus preopticus-periventricularis consists of the nucleus periventricularis and the nucleus preopticus consisting of a few sparse multipolar neurons in the rostral part and numerous cells closely packed and arranged in several layers in its aboral part. The nucleus lateralis tuberis is located in the ventral-lateral area of the diencephalon and is made up of a number of large multipolar neurones. Four different polyclonal primary antibodies against salmon (s)GnRH, chicken (c)GnRH-II (cGnRH-II 675, cGnRH-II 6) and sea bream (sb)GnRH were employed in the immunohistochemical experiments. No immunoreactive structures were found with anti sbGnRH serum. sGnRH and cGnRH-II antisera revealed immunoreactivity in the perikarya of the olfactory bulbs, preopticus-periventricular nucleus, oculomotor nucleus and midbrain tegmentum. The nucleus lateralis tuberis showed immunostaining only with anti-sGnRH serum. Nerve fibres immunoreactive to cGnRH and sGnRH sera were found in the olfactory bulbs, olfactory nerve and neurohypophysis. The significance of the distribution of the GnRH-immunoreactive neuronal structures is discussed. PMID:18502719

  11. Individual Spawning Duration of Captive Atlantic Bluefin Tuna (Thunnus thynnus) Revealed by Mitochondrial DNA Analysis of Eggs

    PubMed Central

    Gordoa, Ana; Sanz, Nuria; Viñas, Jordi

    2015-01-01

    This study presents the first results on Atlantic bluefin tuna (Thunnus thynnus) individual spawning duration and its short-term temporal behavior. The study was based on direct measurements resulting from mtDNA analysis of the offspring of spawners held in transport cages during the 2013 spawning monitoring survey in Balearic waters. The number of females consisted of approximately 259 individuals with an average weight of 186 kg. The survey began on May 22 and ended on July 3. Spawning started on May 30 and was observed every night afterwards. The sampling of eggs for genetic monitoring was conducted for 9 days interspersed from the beginning of spawning to the end of the survey. A total of 946 eggs were analyzed and revealed 129 different haplotypes; 77 of these were not previously detected in the Mediterranean. A total of 69 haplotypes were observed in more than one spawning event and those with higher frequency lasted their maximum possible duration. The haplotypes present at the beginning of spawning were also identified at the end of the sampling, indicating a minimum spawning duration of 34 days, and individual annual fecundity was estimated at around 1290 eggs gr-1. These results differed from those generally presumed until now and are indicative of a much higher fecundity. Females exhibited a regular spawning schedule but with the capacity to shift the spawning hour during the spawning season. These results were observed for the eastern population of Atlantic bluefin tuna and before extrapolating to the western population, their validity should be proved. PMID:26317343

  12. Burst Feeding of Pelagia noctiluca ephyrae on Atlantic Bluefin Tuna (Thunnus thynnus) Eggs

    PubMed Central

    Gordoa, Ana; Acuña, José Luis; Farrés, Roser; Bacher, Kathrin

    2013-01-01

    This study investigates the predation of P. noctiluca ephyrae on Atlantic Bluefin tuna (ABFT) eggs under different experimental conditions. The specific factors considered in the experimental design were: a) water mix conditions to explore predation under two-dimensional (2D) and three-dimensional (3D) prey distributions, b) prey density to investigate the ingestion rate capacity, and c) incubation time to inspect gut saturation. The eggs and jellyfish ephyrae were collected during the 2012 ABFT spawning survey off Ibiza (Balearic Isl., Western Mediterranean). The results showed that the proportion of feeding ephyrae increased with size. The mean clearance rate of feeding ephyrae, 4.14 L h-1, was the highest ever recorded for ephyrae. Under calm conditions the eggs floated at the surface (2D spatial arrangement) and the clearance rates, at low prey densities, were at least twice those under mixed conditions (3D spatial arrangement). At high prey density, clearance rate did not differ between mix conditions, probably due to the fast gut saturation, which was reached in c.a. 15 min, as revealed by time series observations of gut contents. The fast saturation of ephyrae and their slow digestion time of approximately 18 h suggest the existence of a diel feeding periodicity. We conclude that in the Western Mediterranean, P. noctiluca ephyrae are capable of predating on ABFT eggs, a highly pulsed and spatially restricted resource that potentially switches from a 3D to a 2D configuration in the absence of wind-generated turbulence. The P. noctiluca and Atlantic Bluefin tuna egg system might represent an example of a general mechanism linking pelagic and neustonic food webs. PMID:24069335

  13. Kudoa hexapunctata n. sp. (Myxozoa: Multivalvulida) from the somatic muscle of Pacific bluefin tuna Thunnus orientalis and re-description of K. neothunni in yellowfin tuna T. albacares.

    PubMed

    Yokoyama, Hiroshi; Suzuki, Jun; Shirakashi, Sho

    2014-08-01

    Since Kudoa septempunctata in olive flounder (Paralichthys olivaceus) was indicated to cause food poisoning in humans, other Kudoa species are suspected to have pathogenic potential. Recently, a myxosporean possibly associated with food poisoning in humans consuming raw Pacific bluefin tuna, Thunnus orientalis, was identified as Kudoa neothunni. This is a known causative myxosporean of post-harvest myoliquefaction in yellowfin tuna Thunnus albacares. Regardless of the significant differences in the 28S rDNA sequence and the pathological character (with/without myoliquefaction) between the two T. orientalis and T. albacares isolates, they were considered intraspecific variants of K. neothunni. However, the light and low-vacuum electron microscopic observations in the present study revealed that there were two morphotypes; pointed- and round-type spores, which were significantly differentiated by the ratio of suture width to spore width. Furthermore, the two morphotypes were genetically distinguishable by the 28S rDNA sequence analysis. This morphological and molecular evidence validates that the two Kudoa types are separate species, and thus the pointed- and round-types are referred to as K. neothunni and Kudoa hexapunctata n. sp., respectively. K. neothunni was detected solely from T. albacares, whereas K. hexapunctata n. sp. was found not only from T. orientalis but also from T. albacares. PMID:24709084

  14. Metazoan gill parasites of the Atlantic bluefin tuna Thunnus thynnus (Linnaeus) (Osteichthyes: Scombridae) from the Mediterranean and their possible use as biological tags.

    PubMed

    Culurgioni, Jacopo; Mele, Salvatore; Merella, Paolo; Addis, Piero; Figus, Vincenza; Cau, Angelo; Karakulak, Firdes Saadet; Garippa, Giovanni

    2014-04-01

    The gills of 63 specimens of the Atlantic bluefin tuna Thunnus thynnus (Linnaeus) (Osteichthyes: Scombridae) from three localities of the Mediterranean (Sardinian, Tyrrhenian and Levantine Seas) were examined for metazoan parasites. The parasite fauna of T. thynnus from the Sea of Sardinia included 11 species: five didymozoid trematodes, three capsalid and one hexostomid monogeneans, and one caligid and one pseudocycnid copepods. Four didymozoids were found in fish from the Levantine Sea and only one didymozoid was recorded in fish from the Tyrrhenian Sea. Dividing the hosts into four size-groups (small, medium-sized, large and extra large), the pairwise comparison of prevalence and mean abundance of the new and literary data) showed differences according to host size. The differences in the composition of the parasitic faunas and in the prevalence of parasites, observed between the small tunas from the Tyrrhenian Sea and the medium-sized tunas from the Adriatic Sea, Levantine Sea and the North-East (NE) Atlantic Ocean, indicated that these groups form discrete units. The parasite fauna of the large tunas from the Sea of Sardinia is the richest among the bluefin tuna populations of the Mediterranean and the NE Atlantic, due to the presence of species not found elsewhere in bluefin tunas, such as Caligus coryphaenae Steenstrup et Lütken, 1861, Capsala magronum (Ishii, 1936) and C. paucispinosa (Mamaev, 1968). This fact and the prevalence of some parasites of this group (lower than those of medium-sized fish from the NE Atlantic and higher than the small and medium-sized tunas from the Mediterranean) suggest that the large-sized tuna group in the western Mediterranean is formed by Mediterranean resident tunas (poorly infected), and by tunas migrating from the Atlantic Ocean (heavily infected). PMID:24822321

  15. Radiocesium in Pacific bluefin tuna Thunnus orientalis in 2012 validates new tracer technique.

    PubMed

    Madigan, Daniel J; Baumann, Zofia; Snodgrass, Owyn E; Ergül, Halim A; Dewar, Heidi; Fisher, Nicholas S

    2013-03-01

    The detection of Fukushima-derived radionuclides in Pacific bluefin tuna (PBFT) that crossed the Pacific Ocean to the California Current Large Marine Ecosystem (CCLME) in 2011 presented the potential to use radiocesium as a tracer in highly migratory species. This tracer requires that all western Pacific Ocean emigrants acquire the (134)Cs signal, a radioisotope undetectable in Pacific biota prior to the Fukushima accident in 2011. We tested the efficacy of the radiocesium tracer by measuring (134)Cs and (137)Cs in PBFT (n = 50) caught in the CCLME in 2012, more than a year after the Fukushima accident. All small PBFT (n = 28; recent migrants from Japan) had (134)Cs (0.7 ± 0.2 Bq kg(-1)) and elevated (137)Cs (2.0 ± 0.5 Bq kg(-1)) in their white muscle tissue. Most larger, older fish (n = 22) had no (134)Cs and only background levels of (137)Cs, showing that one year in the CCLME is sufficient for (134)Cs and (137)Cs values in PBFT to reach pre-Fukushima levels. Radiocesium concentrations in 2012 PBFT were less than half those from 2011 and well below safety guidelines for public health. Detection of (134)Cs in all recent migrant PBFT supports the use of radiocesium as a tracer in migratory animals in 2012. PMID:23398380

  16. Molecular characterization of kudoid parasites (Myxozoa: Multivalvulida) from somatic muscles of Pacific bluefin (Thunnus orientalis) and yellowfin (T. albacores) tuna.

    PubMed

    Abe, Niichiro; Maehara, Tomofumi

    2013-06-01

    The public health importance of Kudoa infection in fish remains unclear. Recently in Japan a Kudoa species, K. septempunctata, was newly implicated as a causative agent of unidentified food poisoning related to the consumption of raw olive flounder. Other marine fishery products are also suspected as causative raw foods of unidentified food poisoning. For this study, we detected kudoid parasites from sliced raw muscle tissues of a young Pacific bluefin and an adult yellowfin tuna. No cyst or pseudocyst was evident in muscles macroscopically, but pseudocysts were detected in both samples histologically. One substitution (within 1100 bp overlap) and ten substitutions (within 753 bp overlap) were found respectively between the partial sequences of 18S and 28S rDNAs from both isolates. Nucleotide sequence similarity searching of 18S and 28S rDNAs from both isolates showed the highest identity with those of K. neothunni from tuna. Based on the spore morphology, the mode of parasitism, and the nucleotide sequence similarity, these isolates from a Pacific bluefin and a yellowfin tuna were identified as K. neothunni. Phylogenetic analysis of the 28S rDNA sequence revealed that K. neothunni is classifiable into two genotypes: one from Pacific bluefin and the other from yellowfin tuna. Recently, an unidentified kudoid parasite morphologically and genetically similar K. neothunni were detected from stocked tuna samples in unidentified food poisoning cases in Japan. The possibility exists that K. neothunni, especially from the Pacific bluefin tuna, causes food poisoning, as does K. septempunctata. PMID:23666661

  17. Comparative study of liver vitellogenin gene expression and oocyte yolk accumulation in wild and captive Atlantic bluefin tuna (Thunnus thynnus L.).

    PubMed

    Pousis, C; De Giorgi, C; Mylonas, C C; Bridges, C R; Zupa, R; Vassallo-Agius, R; de la Gándara, F; Dileo, C; De Metrio, G; Corriero, A

    2011-01-01

    The sequence of vitellogenin A (VgA) and vitellogenin B (VgB) cDNAs in Atlantic bluefin tuna (Thunnus thynnus L.) were determined, and vitellogenin expression levels in the liver and oocyte yolk accumulation were compared in wild and captive-reared individuals. Liver and ovary samples were taken from 31 individuals reared experimentally in three commercial Atlantic bluefin tuna fattening sites in the Mediterranean Sea and from 33 wild individuals caught by commercial traps during the fish's migration towards their Mediterranean spawning grounds. The total length of VgA cDNA was 5585 nucleotides and that of VgB was 5267 nucleotides. The identity and similarity between deduced amino acid sequences of VgA and VgB were 60% and 78%, respectively. The Atlantic bluefin tuna VgA and VgB amino acid sequences have high similarities with those of other teleost fishes. Relative levels of VgA and VgB mRNAs were low in April, increased significantly during the reproductive period in May and June, and declined in July. There was a trend towards higher relative levels of VgA and VgB mRNAs in captive fish compared to wild individuals during the reproductive period. The surface occupied by eosinophilic yolk granules in fully vitellogenic oocytes, as well as the frequency of oocytes in late vitellogenesis, was significantly higher in captive compared to wild individuals. The study suggests that the experimental conditions under which Atlantic bluefin tuna individuals were reared allowed the occurrence of normal vitellogenesis, based on gene expression of VgA and VgB in the liver and yolk accumulation in the oocytes. The higher yolk accumulation and frequency of vitellogenic oocytes observed in the ovaries of captive fish suggest that improvements in feeding practices may result in an improved vitellogenic process. PMID:21093994

  18. Demographic structure, sex ratio and growth rates of southern bluefin tuna (Thunnus maccoyii) on the spawning ground.

    PubMed

    Farley, Jessica H; Eveson, J Paige; Davis, Tim L O; Andamari, Retno; Proctor, Craig H; Nugraha, Budi; Davies, Campbell R

    2014-01-01

    The demographics of the southern bluefin tuna (SBT) Thunnus maccoyii spawning stock were examined through a large-scale monitoring program of the Indonesian longline catch on the spawning ground between 1995 and 2012. The size and age structure of the spawning population has undergone significant changes since monitoring began. There has been a reduction in the relative abundance of larger/older SBT in the catch since the early 2000s, and a corresponding decrease in mean length and age, but there was no evidence of a significant truncation of the age distribution. Pulses of young SBT appear in the catches in the early- and mid-2000s and may be the first evidence of increased recruitment into the spawning stock since 1995. Fish in these two recruitment pulses were spawned around 1991 and 1997. Size-related variations in sex ratio were also observed with female bias for fish less than 170 cm FL and male bias for fish greater than 170 cm FL. This trend of increasing proportion of males with size above 170 cm FL is likely to be related to sexual dimorphism in growth rates as male length-at-age is greater than that for females after age 10 years. Mean length-at-age of fish aged 8-10 years was greater for both males and females on the spawning ground than off the spawning ground, suggesting that size may be the dominant factor determining timing of maturation in SBT. In addition to these direct results, the data and samples from this program have been central to the assessment and management of this internationally harvested stock. PMID:24797529

  19. Cell proliferation and long chain polyunsaturated fatty acid metabolism in a cell line from southern bluefin tuna (Thunnus maccoyii).

    PubMed

    Scholefield, Andrew M; Schuller, Kathryn A

    2014-07-01

    Southern bluefin tuna (SBT, Thunnus maccoyii) aquaculture is a highly valuable industry, but research on these fish is hampered by strict catch quotas and the limited success of captive breeding. To address these limitations, we have developed a SBT cell line (SBT-E1) and here we report on fatty acid metabolism in this cell line. The SBT-E1 cells proliferated well in standard Leibovitz's L-15 cell culture medium containing fetal bovine serum (FBS) as the source of fatty acids. Decreasing the FBS concentration decreased the cell proliferation. Addition of the C(18) polyunsaturated fatty acids (PUFA) α-linolenic acid (ALA, 18:3n-3) or linoleic acid (LNA, 18:2n-6) to the cell culture medium had little effect on the proliferation of the cells, whereas addition of the long-chain PUFA (LC-PUFA) arachidonic acid (ARA, 20:4n-6), eicosapentaenoic acid (EPA, 20:5n-3) or docosahexaenoic acid (DHA, 22:6n-3) significantly reduced the proliferation of the cells, especially at higher concentrations and especially for DHA. Addition of vitamin E to the culture medium overcame this effect, suggesting that it was due to oxidative stress. The fatty acid profiles of the total lipid from the cells reflected those of the respective culture media with little evidence for desaturation or elongation of any of the fatty acids. The only exceptions were EPA and ARA, which showed substantial elongation to 22:5n-3 and 22:4n-6, respectively, and DHA, which was significantly enriched in the cells compared with the culture medium. The results are discussed in light of the dietary PUFA requirements of SBT in the wild and in aquaculture. PMID:24825740

  20. Demographic Structure, Sex Ratio and Growth Rates of Southern Bluefin Tuna (Thunnus maccoyii) on the Spawning Ground

    PubMed Central

    Farley, Jessica H.; Eveson, J. Paige; Davis, Tim L. O.; Andamari, Retno; Proctor, Craig H.; Nugraha, Budi; Davies, Campbell R.

    2014-01-01

    The demographics of the southern bluefin tuna (SBT) Thunnus maccoyii spawning stock were examined through a large-scale monitoring program of the Indonesian longline catch on the spawning ground between 1995 and 2012. The size and age structure of the spawning population has undergone significant changes since monitoring began. There has been a reduction in the relative abundance of larger/older SBT in the catch since the early 2000s, and a corresponding decrease in mean length and age, but there was no evidence of a significant truncation of the age distribution. Pulses of young SBT appear in the catches in the early- and mid-2000s and may be the first evidence of increased recruitment into the spawning stock since 1995. Fish in these two recruitment pulses were spawned around 1991 and 1997. Size-related variations in sex ratio were also observed with female bias for fish less than 170 cm FL and male bias for fish greater than 170 cm FL. This trend of increasing proportion of males with size above 170 cm FL is likely to be related to sexual dimorphism in growth rates as male length-at-age is greater than that for females after age 10 years. Mean length-at-age of fish aged 8–10 years was greater for both males and females on the spawning ground than off the spawning ground, suggesting that size may be the dominant factor determining timing of maturation in SBT. In addition to these direct results, the data and samples from this program have been central to the assessment and management of this internationally harvested stock. PMID:24797529

  1. Dispersal routes and habitat utilization of juvenile Atlantic bluefin tuna, Thunnus thynnus, tracked with mini PSAT and archival tags.

    PubMed

    Galuardi, Benjamin; Lutcavage, Molly

    2012-01-01

    Between 2005 and 2009, we deployed 58 miniature pop-up satellite archival tags (PSAT) and 132 implanted archival tags on juvenile Atlantic bluefin tuna (age 2-5) in the northwest Atlantic Ocean. Data returned from these efforts (n = 26 PSATs, 1 archival tag) revealed their dispersal routes, horizontal and vertical movements and habitat utilization. All of the tagged bluefin tuna remained in the northwest Atlantic for the duration observed, and in summer months exhibited core-use of coastal seas extending from Maryland to Cape Cod, MA, (USA) out to the shelf break. Their winter distributions were more spatially disaggregated, ranging south to the South Atlantic Bight, northern Bahamas and Gulf Stream. Vertical habitat patterns showed that juvenile bluefin tuna mainly occupied shallow depths (mean= 5-12 m, sd = 15-23.7 m) and relatively warm water masses in summer (mean= 17.9-20.9°C, sd= 4.2-2.6°C) and had deeper and more variable depth patterns in winter (mean= 41-58 m, sd= 48.9-62.2 m). Our tagging results reveal annual dispersal patterns, behavior and oceanographic associations of juvenile Atlantic bluefin tuna that were only surmised in earlier studies. Fishery independent profiling from electronic tagging also provide spatially and temporally explicit information for evaluating dispersals rates, population structure and fisheries catch patterns. PMID:22629461

  2. Seasonal and interannual variability of fat content of juvenile albacore ( Thunnus alalunga) and bluefin ( Thunnus thynnus) tunas during their feeding migration to the Bay of Biscay

    NASA Astrophysics Data System (ADS)

    Goñi, Nicolas; Arrizabalaga, Haritz

    2010-07-01

    The fat content of 2945 juvenile albacore and 618 juvenile bluefin tunas caught in the Bay of Biscay was measured. Individuals were caught in 2004, 2005, 2006 and 2007 from June to early November by pelagic trawling, trolling and baitboat gears. The results for the two species show different seasonal trends. The fat content of albacore tuna increased linearly throughout the fishing season, which reflects their feeding migration. The seasonal trend of bluefin tuna showed a minimum in early August, which may be related to a different behaviour, physiology or feeding strategy. An interannual increase of fat content was observed in albacore tuna and in age-2 to age-5+ bluefin tuna, which is possibly related to a density-dependence phenomenon. The seasonal increase of fat content was strongest and appeared in the four years studied for age-3 and age-4 albacore tuna, which can be related to a different vertical habitat or a more efficient use of their ecological niche by the individuals of these age-groups, relatively to the younger age-groups. Condition factor and girth/length ratio do not appear to be relevant indicators of fat content.

  3. Dispersal Routes and Habitat Utilization of Juvenile Atlantic Bluefin Tuna, Thunnus thynnus, Tracked with Mini PSAT and Archival Tags

    PubMed Central

    Galuardi, Benjamin; Lutcavage, Molly

    2012-01-01

    Between 2005 and 2009, we deployed 58 miniature pop-up satellite archival tags (PSAT) and 132 implanted archival tags on juvenile Atlantic bluefin tuna (age 2–5) in the northwest Atlantic Ocean. Data returned from these efforts (n = 26 PSATs, 1 archival tag) revealed their dispersal routes, horizontal and vertical movements and habitat utilization. All of the tagged bluefin tuna remained in the northwest Atlantic for the duration observed, and in summer months exhibited core-use of coastal seas extending from Maryland to Cape Cod, MA, (USA) out to the shelf break. Their winter distributions were more spatially disaggregated, ranging south to the South Atlantic Bight, northern Bahamas and Gulf Stream. Vertical habitat patterns showed that juvenile bluefin tuna mainly occupied shallow depths (mean  = 5–12 m, sd  = 15–23.7 m) and relatively warm water masses in summer (mean  = 17.9–20.9°C, sd  = 4.2–2.6°C) and had deeper and more variable depth patterns in winter (mean  = 41–58 m, sd  = 48.9–62.2 m). Our tagging results reveal annual dispersal patterns, behavior and oceanographic associations of juvenile Atlantic bluefin tuna that were only surmised in earlier studies. Fishery independent profiling from electronic tagging also provide spatially and temporally explicit information for evaluating dispersals rates, population structure and fisheries catch patterns. PMID:22629461

  4. Molecular Identification of Atlantic Bluefin Tuna (Thunnus thynnus, Scombridae) Larvae and Development of a DNA Character-Based Identification Key for Mediterranean Scombrids.

    PubMed

    Puncher, Gregory Neils; Arrizabalaga, Haritz; Alemany, Francisco; Cariani, Alessia; Oray, Isik K; Karakulak, F Saadet; Basilone, Gualtiero; Cuttitta, Angela; Mazzola, Salvatore; Tinti, Fausto

    2015-01-01

    The Atlantic bluefin tuna, Thunnus thynnus, is a commercially important species that has been severely over-exploited in the recent past. Although the eastern Atlantic and Mediterranean stock is now showing signs of recovery, its current status remains very uncertain and as a consequence their recovery is dependent upon severe management informed by rigorous scientific research. Monitoring of early life history stages can inform decision makers about the health of the species based upon recruitment and survival rates. Misidentification of fish larvae and eggs can lead to inaccurate estimates of stock biomass and productivity which can trigger demands for increased quotas and unsound management conclusions. Herein we used a molecular approach employing mitochondrial and nuclear genes (CO1 and ITS1, respectively) to identify larvae (n = 188) collected from three spawning areas in the Mediterranean Sea by different institutions working with a regional fisheries management organization. Several techniques were used to analyze the genetic sequences (sequence alignments using search algorithms, neighbour joining trees, and a genetic character-based identification key) and an extensive comparison of the results is presented. During this process various inaccuracies in related publications and online databases were uncovered. Our results reveal important differences in the accuracy of the taxonomic identifications carried out by different ichthyoplanktologists following morphology-based methods. While less than half of larvae provided were bluefin tuna, other dominant taxa were bullet tuna (Auxis rochei), albacore (Thunnus alalunga) and little tunny (Euthynnus alletteratus). We advocate an expansion of expertise for a new generation of morphology-based taxonomists, increased dialogue between morphology-based and molecular taxonomists and increased scrutiny of public sequence databases. PMID:26147931

  5. Molecular Identification of Atlantic Bluefin Tuna (Thunnus thynnus, Scombridae) Larvae and Development of a DNA Character-Based Identification Key for Mediterranean Scombrids

    PubMed Central

    Puncher, Gregory Neils; Arrizabalaga, Haritz; Alemany, Francisco; Cariani, Alessia; Oray, Isik K.; Karakulak, F. Saadet; Basilone, Gualtiero; Cuttitta, Angela; Mazzola, Salvatore; Tinti, Fausto

    2015-01-01

    The Atlantic bluefin tuna, Thunnus thynnus, is a commercially important species that has been severely over-exploited in the recent past. Although the eastern Atlantic and Mediterranean stock is now showing signs of recovery, its current status remains very uncertain and as a consequence their recovery is dependent upon severe management informed by rigorous scientific research. Monitoring of early life history stages can inform decision makers about the health of the species based upon recruitment and survival rates. Misidentification of fish larvae and eggs can lead to inaccurate estimates of stock biomass and productivity which can trigger demands for increased quotas and unsound management conclusions. Herein we used a molecular approach employing mitochondrial and nuclear genes (CO1 and ITS1, respectively) to identify larvae (n = 188) collected from three spawning areas in the Mediterranean Sea by different institutions working with a regional fisheries management organization. Several techniques were used to analyze the genetic sequences (sequence alignments using search algorithms, neighbour joining trees, and a genetic character-based identification key) and an extensive comparison of the results is presented. During this process various inaccuracies in related publications and online databases were uncovered. Our results reveal important differences in the accuracy of the taxonomic identifications carried out by different ichthyoplanktologists following morphology-based methods. While less than half of larvae provided were bluefin tuna, other dominant taxa were bullet tuna (Auxis rochei), albacore (Thunnus alalunga) and little tunny (Euthynnus alletteratus). We advocate an expansion of expertise for a new generation of morphology-based taxonomists, increased dialogue between morphology-based and molecular taxonomists and increased scrutiny of public sequence databases. PMID:26147931

  6. Evidence that severe acute stress and starvation induce rapid atresia of ovarian vitellogenic follicles in Atlantic bluefin tuna, Thunnus thynnus (L.) (Osteichthyes: Scombridae).

    PubMed

    Corriero, A; Zupa, R; Bello, G; Mylonas, C C; Deflorio, M; Genovese, S; Basilone, G; Buscaino, G; Buffa, G; Pousis, C; De Metrio, G; Santamaria, N

    2011-11-01

    The effects of different stressors on the atretic degeneration of ovarian vitellogenic follicles, as well as on the ovarian mass, were examined in female Atlantic bluefin tuna, Thunnus thynnus (L.), from the Mediterranean Sea. The stressors taken into consideration were short-term starvation (up to 14 days), long-term cage rearing (1 year) and crowding-induced severe panic frenzy. Wild-caught individuals were used as a control group. Fish subjected to either severe panic frenzy or starvation exhibited a decrease in gonad mass and had significantly higher intensity of α atresia in the vitellogenic follicles (means: 78% and 58%, respectively; range: 36-100%) than either wild or long-term caged individuals (means: 32% and 30%, respectively; range: 19-44%). The extensive atresia in fish stressed by severe panic frenzy was observed as early as 24 h after the stressing event. The present study represents the first evidence of the extreme susceptibility of Atlantic bluefin tuna to severe acute stress during vitellogenesis; it also shows that starvation is associated with progressive reabsorption of vitellogenic oocytes. PMID:21988357

  7. Feeding habits of the Atlantic bluefin tuna, Thunnus thynnus (L. 1758), in the central Mediterranean Sea (Strait of Messina)

    NASA Astrophysics Data System (ADS)

    Battaglia, Pietro; Andaloro, Franco; Consoli, Pierpaolo; Esposito, Valentina; Malara, Danilo; Musolino, Simona; Pedà, Cristina; Romeo, Teresa

    2013-03-01

    The study of feeding habits of the Atlantic bluefin tuna was carried out in 123 specimens, ranging from 115 to 222 cm fork length (FL) and collected during spring seasons of 2010 and 2011 in the central Mediterranean Sea (Strait of Messina). The analysis of stomach contents allowed us to identify 91 taxa of prey items, mainly belonging to Teleostea (54), Cephalopoda (20) and Crustacea (13). The percentage of index of relative abundance ( IRI) shows the highest values for the myctophid Hygophum benoiti (% IRI = 22.854) and the stomiid Chauliodus sloani (% IRI = 15.124), followed by the oegopsid squid Illex coindetii (% IRI = 14.316). The broad spectrum of prey items could suggest a generalist behavior of this predator, with several species that occasionally occurs in its diet. However, if prey are grouped into food categories, the importance of mesopelagic and benthopelagic fishes can be appreciated (54.41 % of % IRI). The assessment of the hypothetical foraging rhythm of the Atlantic bluefin tuna highlighted that its feeding activity is concentrated on diel migrating fauna during night and on larger preys upon daylight. The predation on the high-energetic food as mesopelagic and bathypelagic fishes during the pre-spawning and the spawning period may bring an energetic advantage in tuna metabolism and gonadal maturation

  8. Levels of mercury and organohalogen compounds in Pacific bluefin tuna (Thunnus orientalis) cultured in different regions of Japan.

    PubMed

    Hisamichi, Yohsuke; Haraguchi, Koichi; Endo, Tetsuya

    2012-02-01

    Contamination levels of total mercury (T-Hg), p,p'-DDE, and polychlorinated biphenyls (PCBs) in akami (leaner meat) and toro (fatty meat) samples from Pacific bluefin tuna cultured in the southern (four locations) and central (three locations) regions of Japan were analyzed. The contamination level of T-Hg in the akami and toro samples from the southern region tended to decrease with an increase in latitude, whereas those of p,p'-DDE and PCBs tended to increase. These spatial trends in contaminants were similar to those reported previously in wild tuna caught off the coast of Japan (Hisamichi et al., in Environ Sci Technol 44:5971-5978, 2010). However, the contamination level of T-Hg in akami and toro samples from one location in the central region was the highest among all seven locations, whereas the contamination level of p,p'-DDE was lower than that from any location studied in the southern region. Thus, contamination levels of T-Hg, p,p'-DDE, and PCBs in the cultured tuna may reflect contamination levels not only in the marine environment but also in prey fish used as bait. PMID:21766244

  9. On Making Statistical Inferences Regarding the Relationship between Spawners and Recruits and the Irresolute Case of Western Atlantic Bluefin Tuna (Thunnus thynnus).

    PubMed

    Porch, Clay E; Lauretta, Matthew V

    2016-01-01

    Forecasts of the future abundance of western Atlantic bluefin tuna (Thunnus thynnus) have, for nearly two decades, been based on two competing views of future recruitment potential: (1) a "low" recruitment scenario based on hockey-stick (two-line) curve where the expected level of recruitment is set equal to the geometric mean of the recruitment estimates for the years after a supposed regime-shift in 1975, and (2) a "high" recruitment scenario based on a Beverton-Holt curve fit to the time series of spawner-recruit pairs beginning in 1970. Several investigators inferred the relative plausibility of these two scenarios based on measures of their ability to fit estimates of spawning biomass and recruitment derived from stock assessment outputs. Typically, these comparisons have assumed the assessment estimates of spawning biomass are known without error. It is shown here that ignoring error in the spawning biomass estimates can predispose model-choice approaches to favor the regime-shift hypothesis over the Beverton-Holt curve with higher recruitment potential. When the variance of the observation error approaches that which is typically estimated for assessment outputs, the same model-choice approaches tend to favor the single Beverton-Holt curve. For this and other reasons, it is argued that standard model-choice approaches are insufficient to make the case for a regime shift in the recruitment dynamics of western Atlantic bluefin tuna. A more fruitful course of action may be to move away from the current high/low recruitment dichotomy and focus instead on adopting biological reference points and management procedures that are robust to these and other sources of uncertainty. PMID:27272215

  10. On Making Statistical Inferences Regarding the Relationship between Spawners and Recruits and the Irresolute Case of Western Atlantic Bluefin Tuna (Thunnus thynnus)

    PubMed Central

    Porch, Clay E.; Lauretta, Matthew V.

    2016-01-01

    Forecasts of the future abundance of western Atlantic bluefin tuna (Thunnus thynnus) have, for nearly two decades, been based on two competing views of future recruitment potential: (1) a “low” recruitment scenario based on hockey-stick (two-line) curve where the expected level of recruitment is set equal to the geometric mean of the recruitment estimates for the years after a supposed regime-shift in 1975, and (2) a “high” recruitment scenario based on a Beverton-Holt curve fit to the time series of spawner-recruit pairs beginning in 1970. Several investigators inferred the relative plausibility of these two scenarios based on measures of their ability to fit estimates of spawning biomass and recruitment derived from stock assessment outputs. Typically, these comparisons have assumed the assessment estimates of spawning biomass are known without error. It is shown here that ignoring error in the spawning biomass estimates can predispose model-choice approaches to favor the regime-shift hypothesis over the Beverton-Holt curve with higher recruitment potential. When the variance of the observation error approaches that which is typically estimated for assessment outputs, the same model-choice approaches tend to favor the single Beverton-Holt curve. For this and other reasons, it is argued that standard model-choice approaches are insufficient to make the case for a regime shift in the recruitment dynamics of western Atlantic bluefin tuna. A more fruitful course of action may be to move away from the current high/low recruitment dichotomy and focus instead on adopting biological reference points and management procedures that are robust to these and other sources of uncertainty. PMID:27272215

  11. Mercury and cadmium concentrations in farmed bluefin tuna (Thunnus orientalis) and the suitability of using the caudal peduncle muscle tissue as a monitoring tool.

    PubMed

    Lares, M L; Huerta-Diaz, M A; Marinone, S G; Valdez-Márquez, M

    2012-04-01

    Three regions (cephalic, central, and caudal) of the dorsal and ventral muscle tissue (R1 through R6) and the caudal peduncle muscle tissue (CPMT) of 20 farmed bluefin tuna (Thunnus orientalis) were analyzed for mercury (Hg) and cadmium (Cd) concentrations. Region 1 (cephalic-ventral) had significantly lower concentrations of Hg but significantly higher concentrations of Cd than did the other regions. However, average metal concentrations of all regions (R1 through R6) were only 6% lower for Hg and were not significantly different for Cd from those in the CPMT. Therefore, the CPMT was used to monitor the concentrations of these two metals in more than 100 farmed tuna collected from July 2004 to January 2009 under the assumption that the Cd concentrations in the CPMT would be representative of the Cd concentration in the whole body and that the Hg concentrations would be, in the worst case, overestimated by approximately 6%. The Hg and Cd concentrations in these tuna were inversely related to the condition index, i.e., the tuna in better condition had the lowest concentrations of these metals. The mean concentrations in the CPMT of all fish analyzed were 0.31 ± 0.17 μg/g wet weight for Hg and 0.007 ± 0.006 μg/g wet weight for Cd. These concentrations were below the limits established by Mexican regulations for seafood (1.0 and 0.5 μg/g for Hg and Cd, respectively) and Japan (0.4 μg/g for Hg). PMID:22488061

  12. Influence of swimming speed on metabolic rates of juvenile pacific bluefin tuna and yellowfin tuna.

    PubMed

    Blank, Jason M; Farwell, Charles J; Morrissette, Jeffery M; Schallert, Robert J; Block, Barbara A

    2007-01-01

    Bluefin tuna are endothermic and have higher temperatures, heart rates, and cardiac outputs than tropical tuna. We hypothesized that the increased cardiovascular capacity to deliver oxygen in bluefin may be associated with the evolution of higher metabolic rates. This study measured the oxygen consumption of juvenile Pacific bluefin Thunnus orientalis and yellowfin tuna Thunnus albacares swimming in a swim-tunnel respirometer at 20 degrees C. Oxygen consumption (Mo2) of bluefin (7.1-9.4 kg) ranged from 235+/-38 mg kg(-1) h(-1) at 0.85 body length (BL) s(-1) to 498+/-55 mg kg(-1) h(-1) at 1.80 BL s(-1). Minimal metabolic rates of swimming bluefin were 222+/-24 mg O(2) kg(-1) h(-1) at speeds of 0.75 to 1.0 BL s(-1). Mo2 of T. albacares (3.7-7.4 kg) ranged from 164+/-18 mg kg(-1) h(-1) at 0.65 BL s(-1) to 405+/-105 mg kg(-1) h(-1) at 1.8 BL s(-1). Bluefin tuna had higher metabolic rates than yellowfin tuna at all swimming speeds tested. At a given speed, bluefin had higher metabolic rates and swam with higher tailbeat frequencies and shorter stride lengths than yellowfin. The higher M dot o2 recorded in Pacific bluefin tuna is consistent with the elevated cardiac performance and enhanced capacity for excitation-contraction coupling in cardiac myocytes of these fish. These physiological traits may underlie thermal-niche expansion of bluefin tuna relative to tropical tuna species. PMID:17252513

  13. The Kiss2 receptor (Kiss2r) gene in Southern Bluefin Tuna, Thunnus maccoyii and in Yellowtail Kingfish, Seriola lalandi - functional analysis and isolation of transcript variants.

    PubMed

    Nocillado, J N; Biran, J; Lee, Y Y; Levavi-Sivan, B; Mechaly, A S; Zohar, Y; Elizur, A

    2012-10-15

    The kisspeptin system plays an essential role in reproductive function in vertebrates, particularly in the onset of puberty. We investigated the kisspeptin system in two Perciform teleosts, the Southern Bluefin Tuna (SBT; Thunnus maccoyii), and the Yellowtail Kingfish (YTK; Seriola lalandi), by characterising their kisspeptin 2 receptor (Kiss2r) genes. In addition to the full length Kiss2r cDNA sequences, we have isolated from SBT and YTK a transcript variant that retained an intron. We have further obtained three ytkKiss2r transcript variants that contained deletions. In vitro functional analysis of the full length SBT and YTK Kiss2r showed higher response to Kiss2-10 than to Kiss1-10, with stronger transduction via PKC than PKA. The full length ytkKiss2r and two deletion variants were differentially expressed in the brain of male, but not in female, juvenile YTK treated with increasing doses of Kiss2-10 peptide. In the gonads, the expression level of the ytkKiss2r transcripts did not vary significantly either in the male or female fish. This is the first time that transcript variants of the Kiss2r gene that contain deletions and show responsiveness to treatments with kisspeptin have been reported in any teleost. PMID:22824208

  14. Characterization of three pro-inflammatory cytokines, TNFα1, TNFα2 and IL-1β, in cage-reared Atlantic bluefin tuna Thunnus thynnus.

    PubMed

    Lepen Pleić, Ivana; Secombes, Christopher J; Bird, Steve; Mladineo, Ivona

    2014-01-01

    Atlantic bluefin tuna (BFT) (Thunnus thynnus) is of great economic significance for world aquaculture and therefore it is necessary to ensure optimal and sustainable conditions for the farming of this species. Intensive culture of fish may be limited by infectious diseases that can impact on growth performance and cause heavy losses. However, to date there are no reports of cloning and expression analysis of any major immune genes of Atlantic BFT although some immune genes are known in other BFT species. Therefore the aim of this study was to characterize the first cytokine molecules in Atlantic BFT, through: 1) Isolation of full-length cDNA and gene sequences of TNFα1, TNFα2 and IL-1β, 2) comparison of these molecules to known sequences in other vertebrates, especially teleost fish, by multiple sequence alignment, phylogenetic tree analysis and homology modeling; 3) Quantification of in vivo expression of these cytokines in selected tissues in reared BFT over the duration of the farming process. The results indicated that these three cytokines could have value for monitoring Atlantic BFT health status. Curiously, the liver seemed to be an important site of cytokine production during poor health conditions in this species, perhaps reflecting its role as an important organ involved in fish defenses. PMID:24516871

  15. Fin Spine Bone Resorption in Atlantic Bluefin Tuna, Thunnus thynnus, and Comparison between Wild and Captive-Reared Specimens

    PubMed Central

    Santamaria, Nicoletta; Bello, Giambattista; Pousis, Chrysovalentinos; Vassallo-Agius, Robert; de la Gándara, Fernando; Corriero, Aldo

    2015-01-01

    Bone resorption in the first spine of the first dorsal fin of Atlantic bluefin tuna (ABFT) has long been considered for age estimation studies. In the present paper spine bone resorption was assessed in wild (aged 1 to 13 years) and captive-reared (aged 2 to 11 years) ABFT sampled from the Mediterranean Sea. Total surface (TS), solid surface (SS) and reabsorbed surface (RS) were measured in spine transverse sections in order to obtain proportions of SS and RS. The spine section surface was found to be isometrically correlated to the fish fork length by a power equation. The fraction of solid spine bone progressively decreased according to a logarithmic equation correlating SS/TS to both fish size and age. The values ranged from 57% in the smallest examined individuals to 37% in the largest specimens. This phenomenon was further enhanced in captive-reared ABFT where SS/TS was 22% in the largest measured specimen. The difference between the fraction of SS of wild and captive-reared ABFT was highly significant. In each year class from 1- to 7-year-old wild specimens, the fraction of spine reabsorbed surface was significantly higher in specimens collected from March to May than in those sampled during the rest of the year. In 4-year-old fish the normal SS increase during the summer did not occur, possibly coinciding with their first sexual maturity. According to the correlations between SS/TS and age, the rate of spine bone resorption was significantly higher, even almost double, in captive-reared specimens. This could be attributed to the wider context of systemic dysfunctions occurring in reared ABFT, and may be related to a number of factors, including nutritional deficiencies, alteration of endocrine profile, cortisol-induced stress, and loss of spine functions during locomotion in rearing conditions. PMID:25751271

  16. Distribution of persistent organic pollutants (POPS) IN wild Bluefin tuna (Thunnus thynnus) from different FAO capture zones.

    PubMed

    Chiesa, L M; Labella, G F; Panseri, S; Pavlovic, R; Bonacci, S; Arioli, F

    2016-06-01

    Residues of environmental contaminants in food represent a concern in food safety programs. In this study, the distribution of persistent organic pollutants (POPs) were evaluated in 79 tuna samples from FAO areas 51 (Indian Ocean), 71 (Pacific Ocean), 34 (Atlantic Ocean), and 37 (Mediterranean Sea). 6 polychlorinated biphenyls (PCBs), 16 organochlorines (OCs) and 7 polybrominated biphenyl ethers (PBDEs) were selected as representative compounds according to EFSA POPs monitoring guidelines. An analytical method, based on Accelerated Solvent Extraction (ASE), with an "in-line" clean-up step and GC-MS/MS detection, was developed, validated and applied. PCBs were detected in all FAO areas, with a prevalence of 100% for most of them. In the FAO area 37, only, all PBDEs were detected. Only 5 OCs were detected. The results showed that POPs contamination of tuna reflects FAO area contamination; in particular FAO area 37 was the most polluted. Moreover, tuna muscle was an appropriate matrix for monitoring contamination and for obtaining information about food safety. PMID:27016811

  17. A new satellite technology for tracking the movements of Atlantic bluefin tuna

    PubMed Central

    Block, Barbara A.; Dewar, Heidi; Farwell, Charles; Prince, Eric D.

    1998-01-01

    The movements of Atlantic bluefin tuna (Thunnus thynnus thynnus) have captured the interest of scientists and fishers since the time of Aristotle. This tuna is unique among bony fish for maintaining elevated body temperatures (21°C above ambient) and attaining large size (up to 750 kg). We describe here the use of a pop-off satellite tag, for investigating the Atlantic-wide movements and potential stock overlap of western and eastern Atlantic bluefin tuna. The tag also archives data on water temperatures. The objectives of this study were to evaluate the effectiveness of the technology, study the movements of Atlantic bluefin tuna, examine their thermal niche, and assess survivorship of tagged fish. The pop-off satellite technology provides data independent of commercial fisheries that, when deployed in sufficient quantity, should permit a critical test of the stock structure hypotheses for Atlantic bluefin tuna. PMID:9689089

  18. A Full Lifecycle Bioenergetic Model for Bluefin Tuna

    PubMed Central

    Jusup, Marko; Klanjscek, Tin; Matsuda, Hiroyuki; Kooijman, S. A. L. M.

    2011-01-01

    We formulated a full lifecycle bioenergetic model for bluefin tuna relying on the principles of Dynamic Energy Budget theory. Traditional bioenergetic models in fish research deduce energy input and utilization from observed growth and reproduction. In contrast, our model predicts growth and reproduction from food availability and temperature in the environment. We calibrated the model to emulate physiological characteristics of Pacific bluefin tuna (Thunnus orientalis, hereafter PBT), a species which has received considerable scientific attention due to its high economic value. Computer simulations suggest that (i) the main cause of different growth rates between cultivated and wild PBT is the difference in average body temperature of approximately 6.5°C, (ii) a well-fed PBT individual can spawn an average number of 9 batches per spawning season, (iii) food abundance experienced by wild PBT is rather constant and sufficiently high to provide energy for yearly reproductive cycle, (iv) energy in reserve is exceptionally small, causing the weight-length relationship of cultivated and wild PBT to be practically indistinguishable and suggesting that these fish are poorly equipped to deal with starvation, (v) accelerated growth rate of PBT larvae is connected to morphological changes prior to metamorphosis, while (vi) deceleration of growth rate in the early juvenile stage is related to efficiency of internal heat production. Based on these results, we discuss a number of physiological and ecological traits of PBT, including the reasons for high Feed Conversion Ratio recorded in bluefin tuna aquaculture. PMID:21779352

  19. Determination of temporal spawning patterns and hatching time in response to temperature of Atlantic bluefin tuna (Thunnus thynnus) in the Western Mediterranean.

    PubMed

    Gordoa, Ana; Carreras, Gustavo

    2014-01-01

    This study analysed the temporal pattern of Atlantic bluefin tuna (ABFT) spawning in the Balearic spawning ground and examined its reproductive performance after years in captivity. Furthermore, ABFT hatching time at different on-site temperatures was determined for the first time. Spawning surveys were carried out in 4 spawning seasons (2009-2012) aboard tuna transport vessels. Three groups of spawners were monitored: a captive group transported to the spawning region and monitored throughout the four spawning seasons and two wild groups caught in 2009 and 2010 which were transferred to a monitoring transport cage immediately after being caught. Surface plankton samples were collected nightly, beginning immediately after the first purse seine catches were made and concluding after spawning was observed to have ended. All groups displayed the same spawning hours, restricted between 2:00-5:00 a.m. The captive group, as they got older, shifted towards the earliest hour, suggesting an age influence on reproductive time. The onset of spawning varied annually from the end of May to the beginning of June at temperatures around 19 °C-20 °C, ending by the second week of July. The peak of spawning was consistently around the summer solstice, June 15th-30th. The results showed the negative effect of unstable oceanographic conditions in the spawning process which might influence the annual reproductive success of ABFT. The influence of temperature on hatching time was higher than that observed in other tuna species, twice as fast at 26 °C (23 h) as at 19.5 °C (49 h). Overall, this study shows the strength of the internal mechanism in ABFT that controls spawning traits. Spawning in ABFT is cyclical and highly synchronised on diel and annual scales. We consider that the timing of spawning is rather influenced by day length and its adaptive significance is discussed. PMID:24608107

  20. Determination of Temporal Spawning Patterns and Hatching Time in Response to Temperature of Atlantic Bluefin Tuna (Thunnus thynnus) in the Western Mediterranean

    PubMed Central

    Gordoa, Ana; Carreras, Gustavo

    2014-01-01

    This study analysed the temporal pattern of Atlantic bluefin tuna (ABFT) spawning in the Balearic spawning ground and examined its reproductive performance after years in captivity. Furthermore, ABFT hatching time at different on-site temperatures was determined for the first time. Spawning surveys were carried out in 4 spawning seasons (2009–2012) aboard tuna transport vessels. Three groups of spawners were monitored: a captive group transported to the spawning region and monitored throughout the four spawning seasons and two wild groups caught in 2009 and 2010 which were transferred to a monitoring transport cage immediately after being caught. Surface plankton samples were collected nightly, beginning immediately after the first purse seine catches were made and concluding after spawning was observed to have ended. All groups displayed the same spawning hours, restricted between 2:00–5:00 a.m. The captive group, as they got older, shifted towards the earliest hour, suggesting an age influence on reproductive time. The onset of spawning varied annually from the end of May to the beginning of June at temperatures around 19°C–20°C, ending by the second week of July. The peak of spawning was consistently around the summer solstice, June 15th–30th. The results showed the negative effect of unstable oceanographic conditions in the spawning process which might influence the annual reproductive success of ABFT. The influence of temperature on hatching time was higher than that observed in other tuna species, twice as fast at 26°C (23 h) as at 19.5°C (49 h). Overall, this study shows the strength of the internal mechanism in ABFT that controls spawning traits. Spawning in ABFT is cyclical and highly synchronised on diel and annual scales. We consider that the timing of spawning is rather influenced by day length and its adaptive significance is discussed. PMID:24608107

  1. Modelling retention and dispersion mechanisms of bluefin tuna eggs and larvae in the northwest Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Mariani, Patrizio; MacKenzie, Brian R.; Iudicone, Daniele; Bozec, Alexandra

    2010-07-01

    Knowledge of early life history of most fish species in the Mediterranean Sea is sparse and processes affecting their recruitment are poorly understood. This is particularly true for bluefin tuna, Thunnus thynnus, even though this species is one of the world’s most valued fish species. Here we develop, apply and validate an individually based coupled biological-physical oceanographic model of fish early life history in the Mediterranean Sea. We first validate the general structure of the coupled model with a 12-day Lagrangian drift study of anchovy ( Engraulis encrasicolus) larvae in the Catalan Sea. The model reproduced the drift and growth of anchovy larvae as they drifted along the Catalan coast and yielded similar patterns as those observed in the field. We then applied the model to investigate transport and retention processes affecting the spatial distribution of bluefin tuna eggs and larvae during 1999-2003, and we compared modelled distributions with available field data collected in 2001 and 2003. Modelled and field distributions generally coincided and were patchy at mesoscales (10s-100s km); larvae were most abundant in eddies and along frontal zones. We also identified probable locations of spawning bluefin tuna using hydrographic backtracking procedures; these locations were situated in a major salinity frontal zone and coincided with distributions of an electronically tagged bluefin tuna and commercial bluefin tuna fishing vessels. Moreover, we hypothesized that mesoscale processes are responsible for the aggregation and dispersion mechanisms in the area and showed that these processes were significantly correlated to atmospheric forcing processes over the NW Mediterranean Sea. Interannual variations in average summer air temperature can reduce the intensity of ocean mesoscale processes in the Balearic area and thus potentially affect bluefin tuna larvae. These modelling approaches can increase understanding of bluefin tuna recruitment processes and

  2. Trophic ecology of Atlantic Bluefin Tuna (Thunnus thynnus) [corrected] larvae from the Gulf of Mexico and NW Mediterranean spawning grounds: A Comparative Stable Isotope Study.

    PubMed

    Laiz-Carrión, Raúl; Gerard, Trika; Uriarte, Amaya; Malca, Estrella; Quintanilla, José María; Muhling, Barbara A; Alemany, Francisco; Privoznik, Sarah L; Shiroza, Akihiro; Lamkin, John T; García, Alberto

    2015-01-01

    The present study uses stable isotopes of nitrogen and carbon (δ15Nandδ13C) as trophic indicators for Atlantic bluefin tuna larvae (BFT) (6-10 mm standard length) in the highly contrasting environmental conditions of the Gulf of Mexico (GOM) and the Balearic Sea (MED). These regions are differentiated by their temperature regime and relative productivity, with the GOM being significantly warmer and more productive. MED BFT larvae showed the highest δ15N signatures, implying an elevated trophic position above the underlying microzooplankton baseline. Ontogenetic dietary shifts were observed in the BFT larvae from the GOM and MED which indicates early life trophodynamics differences between these spawning habitats. Significant trophic differences between the GOM and MED larvae were observed in relation to δ15N signatures in favour of the MED larvae, which may have important implications in their growth during their early life stages.These low δ15N levels in the zooplankton from the GOM may be an indication of a shifting isotopic baseline in pelagic food webs due to diatrophic inputs by cyanobacteria. Lack of enrichment for δ15N in BFT larvae compared to zooplankton implies an alternative grazing pathway from the traditional food chain of phytoplankton-zooplankton-larval fish. Results provide insight for a comparative characterization of the trophic pathways variability of the two main spawning grounds for BFT larvae. PMID:26225849

  3. Lipid and fatty acid composition, and persistent organic pollutant levels in tissues of migrating Atlantic bluefin tuna (Thunnus thynnus, L.) broodstock.

    PubMed

    Sprague, M; Dick, J R; Medina, A; Tocher, D R; Bell, J G; Mourente, G

    2012-12-01

    Lipid class, fatty acid and POP levels were measured in migrating Atlantic bluefin tuna (ABT) tissues caught off the Barbate coast, Spain. Tissue lipids were largely characterized by triacylglycerol, reflecting large energy reserves accumulated prior to reproductive migration. Fatty acid compositions of muscle, liver and adipose exhibited similar profiles, whereas gonads showed a higher affinity for docosahexaenoic acid. Tissue POP concentrations correlated positively with percentage triacylglycerol and negatively with polar lipids. Highest POP concentrations were in adipose and lowest in gonads, reflecting lipid content. DL-PCBs contributed most to total PCDD/F + DL-PCB levels, with mono-ortho concentrations higher in tissues, whereas non-ortho PCBs contributed greater WHO-TEQs due to differences in TEFs. PBDE47 was the most prominent BDE congener in tissues, probably through biotransformation of BDE99 and other higher brominated congeners. The perceived POP risk from ABT consumption should be balanced by the well-established beneficial effects on human health of omega-3 fatty acids. PMID:22885218

  4. Transcriptomic features associated with energy production in the muscles of Pacific bluefin tuna and Pacific cod.

    PubMed

    Shibata, Mami; Mekuchi, Miyuki; Mori, Kazuki; Muta, Shigeru; Chowdhury, Vishwajit Sur; Nakamura, Yoji; Ojima, Nobuhiko; Saitoh, Kenji; Kobayashi, Takanori; Wada, Tokio; Inouye, Kiyoshi; Kuhara, Satoru; Tashiro, Kosuke

    2016-06-01

    Bluefin tuna are high-performance swimmers and top predators in the open ocean. Their swimming is grounded by unique features including an exceptional glycolytic potential in white muscle, which is supported by high enzymatic activities. Here we performed high-throughput RNA sequencing (RNA-Seq) in muscles of the Pacific bluefin tuna (Thunnus orientalis) and Pacific cod (Gadus macrocephalus) and conducted a comparative transcriptomic analysis of genes related to energy production. We found that the total expression of glycolytic genes was much higher in the white muscle of tuna than in the other muscles, and that the expression of only six genes for glycolytic enzymes accounted for 83.4% of the total. These expression patterns were in good agreement with the patterns of enzyme activity previously reported. The findings suggest that the mRNA expression of glycolytic genes may contribute directly to the enzymatic activities in the muscles of tuna. PMID:26924100

  5. Pacific bluefin tuna transport Fukushima-derived radionuclides from Japan to California.

    PubMed

    Madigan, Daniel J; Baumann, Zofia; Fisher, Nicholas S

    2012-06-12

    The Fukushima Dai-ichi release of radionuclides into ocean waters caused significant local and global concern regarding the spread of radioactive material. We report unequivocal evidence that Pacific bluefin tuna, Thunnus orientalis, transported Fukushima-derived radionuclides across the entire North Pacific Ocean. We measured γ-emitting radionuclides in California-caught tunas and found (134)Cs (4.0 ± 1.4 Bq kg(-1)) and elevated (137)Cs (6.3 ± 1.5 Bq kg(-1)) in 15 Pacific bluefin tuna sampled in August 2011. We found no (134)Cs and background concentrations (~1 Bq kg(-1)) of (137)Cs in pre-Fukushima bluefin and post-Fukushima yellowfin tunas, ruling out elevated radiocesium uptake before 2011 or in California waters post-Fukushima. These findings indicate that Pacific bluefin tuna can rapidly transport radionuclides from a point source in Japan to distant ecoregions and demonstrate the importance of migratory animals as transport vectors of radionuclides. Other large, highly migratory marine animals make extensive use of waters around Japan, and these animals may also be transport vectors of Fukushima-derived radionuclides to distant regions of the North and South Pacific Oceans. These results reveal tools to trace migration origin (using the presence of (134)Cs) and potentially migration timing (using (134)Cs:(137)Cs ratios) in highly migratory marine species in the Pacific Ocean. PMID:22645346

  6. Pacific bluefin tuna transport Fukushima-derived radionuclides from Japan to California

    PubMed Central

    Madigan, Daniel J.; Baumann, Zofia; Fisher, Nicholas S.

    2012-01-01

    The Fukushima Dai-ichi release of radionuclides into ocean waters caused significant local and global concern regarding the spread of radioactive material. We report unequivocal evidence that Pacific bluefin tuna, Thunnus orientalis, transported Fukushima-derived radionuclides across the entire North Pacific Ocean. We measured γ-emitting radionuclides in California-caught tunas and found 134Cs (4.0 ± 1.4 Bq kg−1) and elevated 137Cs (6.3 ± 1.5 Bq kg−1) in 15 Pacific bluefin tuna sampled in August 2011. We found no 134Cs and background concentrations (∼1 Bq kg−1) of 137Cs in pre-Fukushima bluefin and post-Fukushima yellowfin tunas, ruling out elevated radiocesium uptake before 2011 or in California waters post-Fukushima. These findings indicate that Pacific bluefin tuna can rapidly transport radionuclides from a point source in Japan to distant ecoregions and demonstrate the importance of migratory animals as transport vectors of radionuclides. Other large, highly migratory marine animals make extensive use of waters around Japan, and these animals may also be transport vectors of Fukushima-derived radionuclides to distant regions of the North and South Pacific Oceans. These results reveal tools to trace migration origin (using the presence of 134Cs) and potentially migration timing (using 134Cs:137Cs ratios) in highly migratory marine species in the Pacific Ocean. PMID:22645346

  7. 76 FR 18504 - Atlantic Highly Migratory Species; Atlantic Bluefin Tuna Quotas and Atlantic Tuna Fisheries...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-04

    .... See SUPPLEMENTARY INFORMATION for further details. ADDRESSES: As published on March 14, 2011 (76 FR... Species; Atlantic Bluefin Tuna Quotas and Atlantic Tuna Fisheries Management Measures AGENCY: National... bluefin tuna (BFT) base quotas for all domestic fishing categories; establish BFT quota specifications...

  8. Sexual maturity in western Atlantic bluefin tuna.

    PubMed

    Heinisch, Gilad; Rosenfeld, Hanna; Knapp, Jessica M; Gordin, Hillel; Lutcavage, Molly E

    2014-01-01

    We introduce a novel endocrine approach for assessing the unresolved matter of the timing of sexual maturation in western Atlantic bluefin tuna (ABFT), a highly migratory population whose status remains uncertain. Ratios of follicle stimulating hormone to luteinizing hormone, a sexual maturity indicator, in all ABFT ≥ 134 cm curved fork length (CFL) were <0.4, similar to Mediterranean spawners, indicating that western ABFT mature at considerably smaller sizes and at a much younger age than currently assumed (≥ 185 cm CFL). PMID:25431301

  9. The imprint of anthropogenic CO2 emissions on Atlantic bluefin tuna otoliths

    NASA Astrophysics Data System (ADS)

    Fraile, Igaratza; Arrizabalaga, Haritz; Groeneveld, Jeroen; Kölling, Martin; Santos, Miguel Neves; Macías, David; Addis, Piero; Dettman, David L.; Karakulak, Saadet; Deguara, Simeon; Rooker, Jay R.

    2016-06-01

    Otoliths of Atlantic bluefin tuna (Thunnus thynnus) collected from the Mediterranean Sea and North Atlantic Ocean were analyzed to evaluate changes in the seawater isotopic composition over time. We report an annual otolith δ13C record that documents the magnitude of the δ13C depletion in the Mediterranean Sea between 1989 and 2010. Atlantic bluefin tuna in our sample (n = 632) ranged from 1 to 22 years, and otolith material corresponding to the first year of life (back-calculated birth year) was used to reconstruct seawater isotopic composition. Otolith δ18O remained relatively stable between 1989 and 2010, whereas a statistically significant decrease in δ13C was detected across the time interval investigated, with a rate of decline of 0.05‰ yr- 1 (- 0.94‰ depletion throughout the recorded period). The depletion in otolith δ13C over time was associated with the oceanic uptake of anthropogenically derived CO2.

  10. Spawning of Bluefin Tuna in the Black Sea: Historical Evidence, Environmental Constraints and Population Plasticity

    PubMed Central

    MacKenzie, Brian R.; Mariani, Patrizio

    2012-01-01

    The lucrative and highly migratory Atlantic bluefin tuna, Thunnus thynnus (Linnaeus 1758; Scombridae), used to be distributed widely throughout the north Atlantic Ocean, Mediterranean Sea and Black Sea. Its migrations have supported sustainable fisheries and impacted local cultures since antiquity, but its biogeographic range has contracted since the 1950s. Most recently, the species disappeared from the Black Sea in the late 1980s and has not yet recovered. Reasons for the Black Sea disappearance, and the species-wide range contraction, are unclear. However bluefin tuna formerly foraged and possibly spawned in the Black Sea. Loss of a locally-reproducing population would represent a decline in population richness, and an increase in species vulnerability to perturbations such as exploitation and environmental change. Here we identify the main genetic and phenotypic adaptations that the population must have (had) in order to reproduce successfully in the specific hydrographic (estuarine) conditions of the Black Sea. By comparing hydrographic conditions in spawning areas of the three species of bluefin tunas, and applying a mechanistic model of egg buoyancy and sinking rate, we show that reproduction in the Black Sea must have required specific adaptations of egg buoyancy, fertilisation and development for reproductive success. Such adaptations by local populations of marine fish species spawning in estuarine areas are common as is evident from a meta-analysis of egg buoyancy data from 16 species of fish. We conclude that these adaptations would have been necessary for successful local reproduction by bluefin tuna in the Black Sea, and that a locally-adapted reproducing population may have disappeared. Recovery of bluefin tuna in the Black Sea, either for spawning or foraging, will occur fastest if any remaining locally adapted individuals are allowed to survive, and by conservation and recovery of depleted Mediterranean populations which could through time re

  11. 77 FR 19175 - Atlantic Highly Migratory Species; 2012 Atlantic Bluefin Tuna Quota Specifications

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-30

    ... INFORMATION for further details. ADDRESSES: As published on March 16, 2012 (77 FR 15712), you may submit... Species; 2012 Atlantic Bluefin Tuna Quota Specifications AGENCY: National Marine Fisheries Service (NMFS.... SUPPLEMENTARY INFORMATION: Atlantic bluefin tuna, bigeye tuna, albacore tuna, yellowfin tuna, and skipjack...

  12. Evolutionary changes of multiple visual pigment genes in the complete genome of Pacific bluefin tuna.

    PubMed

    Nakamura, Yoji; Mori, Kazuki; Saitoh, Kenji; Oshima, Kenshiro; Mekuchi, Miyuki; Sugaya, Takuma; Shigenobu, Yuya; Ojima, Nobuhiko; Muta, Shigeru; Fujiwara, Atushi; Yasuike, Motoshige; Oohara, Ichiro; Hirakawa, Hideki; Chowdhury, Vishwajit Sur; Kobayashi, Takanori; Nakajima, Kazuhiro; Sano, Motohiko; Wada, Tokio; Tashiro, Kosuke; Ikeo, Kazuho; Hattori, Masahira; Kuhara, Satoru; Gojobori, Takashi; Inouye, Kiyoshi

    2013-07-01

    Tunas are migratory fishes in offshore habitats and top predators with unique features. Despite their ecological importance and high market values, the open-ocean lifestyle of tuna, in which effective sensing systems such as color vision are required for capture of prey, has been poorly understood. To elucidate the genetic and evolutionary basis of optic adaptation of tuna, we determined the genome sequence of the Pacific bluefin tuna (Thunnus orientalis), using next-generation sequencing technology. A total of 26,433 protein-coding genes were predicted from 16,802 assembled scaffolds. From these, we identified five common fish visual pigment genes: red-sensitive (middle/long-wavelength sensitive; M/LWS), UV-sensitive (short-wavelength sensitive 1; SWS1), blue-sensitive (SWS2), rhodopsin (RH1), and green-sensitive (RH2) opsin genes. Sequence comparison revealed that tuna's RH1 gene has an amino acid substitution that causes a short-wave shift in the absorption spectrum (i.e., blue shift). Pacific bluefin tuna has at least five RH2 paralogs, the most among studied fishes; four of the proteins encoded may be tuned to blue light at the amino acid level. Moreover, phylogenetic analysis suggested that gene conversions have occurred in each of the SWS2 and RH2 loci in a short period. Thus, Pacific bluefin tuna has undergone evolutionary changes in three genes (RH1, RH2, and SWS2), which may have contributed to detecting blue-green contrast and measuring the distance to prey in the blue-pelagic ocean. These findings provide basic information on behavioral traits of predatory fish and, thereby, could help to improve the technology to culture such fish in captivity for resource management. PMID:23781100

  13. A possible explanation for the population size discrepancy in tuna (genus Thunnus) estimated from mitochondrial DNA and microsatellite data.

    PubMed

    Qiu, Fan; Kitchen, Andrew; Beerli, Peter; Miyamoto, Michael M

    2013-02-01

    A recent study using both mitochondrial DNA (mtDNA) and microsatellite data reported on a population size discrepancy in the eastern tiger salamander where the effective population size (N(e)) estimate of the former exceeded that of the latter. That study suggested, among other hypotheses, that homoplasy of microsatellite alleles is responsible for the discrepancy. In this investigation, we report 10 new cases of a similar discrepancy in five species of tuna. These cases derive from our Bayesian inferences using data from Pacific Bluefin Tuna (Thunnus orientalis) and Yellowfin Tuna (Thunnus albacares), as well as from published estimates of genetic diversity for additional populations of Yellowfin Tuna and three other tuna species. Phylogenetic character analyses of inferred genealogies of Pacific Bluefin and Yellowfin Tuna reveal similar reduced levels of mtDNA and microsatellite homoplasy. Thus, the discrepancy between inferred population sizes from mtDNA and microsatellite data in tuna is most likely not an artifact of the chosen mutation models used in the microsatellite analyses, but may reflect behavioral differences between the sexes such as female-biased philopatry and male-biased dispersal. This explanation now warrants critical testing with more local populations of tuna and with other animal and plant groups that have different life histories. PMID:22579759

  14. Electronic tagging and population structure of Atlantic bluefin tuna.

    PubMed

    Block, Barbara A; Teo, Steven L H; Walli, Andreas; Boustany, Andre; Stokesbury, Michael J W; Farwell, Charles J; Weng, Kevin C; Dewar, Heidi; Williams, Thomas D

    2005-04-28

    Electronic tags that archive or transmit stored data to satellites have advanced the mapping of habitats used by highly migratory fish in pelagic ecosystems. Here we report on the electronic tagging of 772 Atlantic bluefin tuna in the western Atlantic Ocean in an effort to identify population structure. Reporting electronic tags provided accurate location data that show the extensive migrations of individual fish (n = 330). Geoposition data delineate two populations, one using spawning grounds in the Gulf of Mexico and another from the Mediterranean Sea. Transatlantic movements of western-tagged bluefin tuna reveal site fidelity to known spawning areas in the Mediterranean Sea. Bluefin tuna that occupy western spawning grounds move to central and eastern Atlantic foraging grounds. Our results are consistent with two populations of bluefin tuna with distinct spawning areas that overlap on North Atlantic foraging grounds. Electronic tagging locations, when combined with US pelagic longline observer and logbook catch data, identify hot spots for spawning bluefin tuna in the northern slope waters of the Gulf of Mexico. Restrictions on the time and area where longlining occurs would reduce incidental catch mortalities on western spawning grounds. PMID:15858572

  15. Single nucleotide polymorphism discovery in albacore and Atlantic bluefin tuna provides insights into worldwide population structure.

    PubMed

    Albaina, A; Iriondo, M; Velado, I; Laconcha, U; Zarraonaindia, I; Arrizabalaga, H; Pardo, M A; Lutcavage, M; Grant, W S; Estonba, A

    2013-12-01

    The optimal management of the commercially important, but mostly over-exploited, pelagic tunas, albacore (Thunnus alalunga Bonn., 1788) and Atlantic bluefin tuna (BFT; Thunnus thynnus L., 1758), requires a better understanding of population structure than has been provided by previous molecular methods. Despite numerous studies of both species, their population structures remain controversial. This study reports the development of single nucleotide polymorphisms (SNPs) in albacore and BFT and the application of these SNPs to survey genetic variability across the geographic ranges of these tunas. A total of 616 SNPs were discovered in 35 albacore tuna by comparing sequences of 54 nuclear DNA fragments. A panel of 53 SNPs yielded FST values ranging from 0.0 to 0.050 between samples after genotyping 460 albacore collected throughout the distribution of this species. No significant heterogeneity was detected within oceans, but between-ocean comparisons (Atlantic, Pacific and Indian oceans along with Mediterranean Sea) were significant. Additionally, a 17-SNP panel was developed in Atlantic BFT by cross-species amplification in 107 fish. This limited number of SNPs discriminated between samples from the two major spawning areas of Atlantic BFT (FST  = 0.116). The SNP markers developed in this study can be used to genotype large numbers of fish without the need for standardizing alleles among laboratories. PMID:23668670

  16. Comparative Assessment of the Reproductive Status of Female Atlantic Bluefin Tuna from the Gulf of Mexico and the Mediterranean Sea

    PubMed Central

    Knapp, Jessica M.; Aranda, Guillermo; Medina, Antonio; Lutcavage, Molly

    2014-01-01

    Despite attention focused on the population status and rebuilding trajectory of Atlantic bluefin tuna (Thunnus thynnus), the reproduction and spawning biology remains poorly understood, especially in the NW Atlantic. At present, the eastern and western spawning populations are believed to exhibit different reproductive characteristics and, consequently, stock productivity. However, our study suggests that the two spawning populations, the Gulf of Mexico and the Mediterranean Sea, could show similar reproductive features and spawning strategies. Between 2007 and 2009, gonad samples from female Atlantic bluefin tuna were collected in the northern Gulf of Mexico (n = 147) and in the western Mediterranean Sea (n = 40). The histological and stereological analysis confirmed that sampled eastern and western bluefin tuna exhibit the same spawning duration (three months) but the spawning in the Gulf of Mexico begins one month earlier than in the Mediterranean Sea. Western bluefin tuna caught in the peak of the spawning season (May) showed a similar spawning frequency (60%) to the spawning peak observed in the Mediterranean Sea (June). Fecundity for the Gulf of Mexico fish () was lower but not significantly different than for fish sampled in the Mediterranean Sea (). Our study represents the first comparative histological analysis of the eastern and western spawning stocks whose findings, combined with new determinations of size/age at maturity and possible alternative spawning areas, might suggest basic life history attributes warrant further scientific and management attention. PMID:24911973

  17. Moving Cages Further Offshore: Effects on Southern Bluefin Tuna, T. maccoyii, Parasites, Health and Performance

    PubMed Central

    Kirchhoff, Nicole T.; Rough, Kirsty M.; Nowak, Barbara F.

    2011-01-01

    The effects of offshore aquaculture on SBT health (particularly parasitic infections and haematology) and performance were the main aim of this study. Two cohorts of ranched Southern Bluefin tuna (SBT) (Thunnus maccoyii) were monitored throughout the commercial season, one maintained in the traditional near shore tuna farming zone and one maintained further offshore. SBT maintained offshore had reduced mortality, increased condition index at week 6 post transfer, reduced blood fluke and sealice loads, and haematological variables such as haemoglobin or lysozyme equal to or exceeding near shore maintained fish. The offshore cohort had no Cardicola forsteri and a 5% prevalence of Caligus spp., compared to a prevalence of 85% for Cardicola forsteri and 55% prevalence for Caligus spp. near shore at 6 weeks post transfer. This study is the first of its kind to examine the effects of commercial offshore sites on farmed fish parasites, health and performance. PMID:21901129

  18. Potential impact of climate change on the Intra-Americas Sea: Part 2. Implications for Atlantic bluefin tuna and skipjack tuna adult and larval habitats

    NASA Astrophysics Data System (ADS)

    Muhling, Barbara A.; Liu, Yanyun; Lee, Sang-Ki; Lamkin, John T.; Roffer, Mitchell A.; Muller-Karger, Frank; Walter, John F., III

    2015-08-01

    Increasing water temperatures due to climate change will likely have significant impacts on distributions and life histories of Atlantic tunas. In this study, we combined predictive habitat models with a downscaled climate model to examine potential impacts on adults and larvae of Atlantic bluefin tuna (Thunnus thynnus) and skipjack tuna (Katsuwonus pelamis) in the Intra-Americas Sea (IAS). An additional downscaled model covering the 20th century was used to compare habitat fluctuations from natural variability to predicted future changes under two climate change scenarios: Representative Concentration Pathway (RCP) 4.5 (medium-low) and RCP 8.5 (high). Results showed marked temperature-induced habitat losses for both adult and larval bluefin tuna on their northern Gulf of Mexico spawning grounds. In contrast, habitat suitability for skipjack tuna increased as temperatures warmed. Model error was highest for the two skipjack tuna models, particularly at higher temperatures. This work suggests that influences of climate change on highly migratory Atlantic tuna species are likely to be substantial, but strongly species-specific. While impacts on fish populations remain uncertain, these changes in habitat suitability will likely alter the spatial and temporal availability of species to fishing fleets, and challenge equilibrium assumptions of environmental stability, upon which fisheries management benchmarks are based.

  19. Characterization of the spawning habitat of Atlantic bluefin tuna and related species in the Balearic Sea (western Mediterranean)

    NASA Astrophysics Data System (ADS)

    Alemany, F.; Quintanilla, L.; Velez-Belchí, P.; García, A.; Cortés, D.; Rodríguez, J. M.; Fernández de Puelles, M. L.; González-Pola, C.; López-Jurado, J. L.

    2010-07-01

    Within the framework of the TUNIBAL project that focused on Atlantic bluefin tuna ( Thunnus thynnus) larval ecology, ichthyoplankton surveys were conducted from 2001 to 2005 off the Balearic archipelago, which is recognized as one of the main spawning areas of the eastern Atlantic stock of this species. In each survey, a regular sampling grid of about 200 stations, 10 nautical miles apart were sampled. CTD casts and oblique Bongo 60 and surface Bongo 90 plankton tows were carried out. The occurrence frequencies of Atlantic bluefin tuna, albacore tuna ( Thunnus alalunga) and bullet tuna ( Auxis rochei) larvae in quantitative Bongo 60 samples were 0.14, 0.29 and 0.49 respectively. Mean larval abundances in these positive samples were relatively high: 31 larvae 10 m -2 for Atlantic bluefin tuna, 17 for albacore tuna and 31 for bullet tuna. All species had patchy distributions since more than 90% of the stations showed larval densities under 10 larvae 100 m -3 (70% showed even less than 2 larvae 100 m -3), whereas in some isolated spots, we recorded abundances as high as 867 (Atlantic bluefin) or 872 (bullet tuna) larvae 10 m -2. These results allowed us to relate larval distribution to mesoscale hydrographic features and to characterize the spawning habitat of these species. Single Quotient Parameter analyses were applied to spatial (depth), physical (temperature, salinity, dissolved oxygen and geostrophic current velocities) and biological (mesozooplankton biomass) variables to determine the environmental preferences of each species for spawning. Results showed that the complex hydrodynamic scenarios around the Balearic Islands, due to the interaction between the inflowing surface Atlantic water masses (AW) and Mediterranean surface waters (MW), play a key role in determining the abundance and distribution of tuna larvae in this area, especially in the case of Atlantic bluefin tuna. Spawning of this species seems to take place mainly in offshore mixed waters, as

  20. Gulf of Mexico Ecological Forecasting - Atlantic Bluefin Tuna Population Assessment and Management using Synthetic Aperture Radar (SAR) Data

    NASA Astrophysics Data System (ADS)

    Laygo, K.; Jones, I.; Huerta, J.; Holt, B.

    2010-12-01

    Atlantic Bluefin Tuna (Thunnus thynnus) is one of the largest vertebrates in the world and is in high demand in sushi markets. It is a highly political species and is managed internationally by the International Commission for the Conservation of Atlantic Tuna. The Gulf of Mexico and the Mediterranean Sea are the only two known spawning sites in the world. However, there is a large variance in estimates of adult Atlantic Tuna spawning. This research focuses on extending Earth science research results to existing decision-making systems, National Oceanic and Atmospheric Administration (NOAA) and the National Marine Fisheries Service (NMFS)for population assessment and management of Atlantic Bluefin Tuna. The research team is a multi-sector and multi-disciplinary team composed of government (NOAA_NMFS), academic (University of South Florida Institute for Marine Remote Sensing) and commercial (Roffer’s Ocean Fishing Forecasting Service, Inc.) institutions. Their goal is to reduce the variance in the estimates of adult Bluefin Tuna spawning stock abundance in the Gulf of Mexico (GOM). Therefore, this paper will be derived from the innovative use of several earth orbiting satellites focusing on the use of synthetic aperture radar (SAR) data to identify Sargassum, which is a floating marine algae that may be relevant to the presence of Bluefin Tuna aggregations. The SAR imagery will be examined in combination with MODIS and MERIS Chlorophyll-a products to detect fine-scale surface current shear, eddy and frontal features, as well as biological slicks due to the presence of Sargassum. In addition, wind records from NOAA buoy data will be studied to analyze wind patterns in the Gulf of Mexico. The fine-resolution, all-weather capabilities of SAR provide a valuable complement to optical/IR sensors, which are often impacted by cloud cover. This study will provide an assessment of whether or not SAR can contribute to decision support efforts relevant to commercial fisheries

  1. Comparative phylogeography of Atlantic bluefin tuna and swordfish: the combined effects of vicariance, secondary contact, introgression, and population expansion on the regional phylogenies of two highly migratory pelagic fishes.

    PubMed

    Alvarado Bremer, Jaime R; Viñas, Jordi; Mejuto, Jaime; Ely, Bert; Pla, Carles

    2005-07-01

    Comparative phylogeography has revealed remarkable patterns of concordance in the maternal phylogenies of many species. The phylogeography and historical demography of the mitochondrial control region I for 607 Atlantic bluefin tuna (Thunnus thynnus) and 275 swordfish (Xiphias gladius) were analyzed to clarify the complex phylogenetic signals in the North Atlantic-Mediterranean region where they are sympatric. Atlantic bluefin tuna mtDNA is polyphyletic, and includes rare sequences sister to Pacific bluefin tuna (Thunnus orientalis) and introgressed albacore (Thunnus alalunga) sequences. There is no geographic partitioning between Atlantic and Mediterranean samples of Atlantic bluefin tuna (Phi(ST)=0.002). In contrast, Atlantic and Mediterranean swordfish are differentiated (Phi(ST)=0.091) due to the combined effects of vicariance, secondary contact, and dissimilar regional demographic histories. Mediterranean swordfish has substantially less variation, and a more recent history (tau=2.42) than that of Atlantic swordfish (tau=7.02). In spite of the discordant phylogenetic and phylogeographic signals, the demographic history of Atlantic swordfish and Atlantic bluefin tuna (tau=7.51) suggests concordance in the timeline of population expansion. Possible scenarios of cladogenesis, expansion, and contraction, influenced by glacial cycles during the Pleistocene, are formulated. PMID:15904864

  2. Physiological and behavioural thermoregulation in bigeye tuna (Thunnus obesus).

    PubMed

    Holland, K N; Brill, R W; Chang, R K; Sibert, J R; Fournier, D A

    1992-07-30

    Tuna are unique among teleost fishes in being thermoconserving. Vascular counter-current heat exchangers maintain body temperatures above ambient water temperature, thereby improving locomotor muscle efficiency, especially at burst speeds and when pursuing prey below the thermocline. Because tuna also occasionally swim rapidly in warm surface waters, it has been hypothesized that tuna thermoregulate to accommodate changing activity levels or ambient temperatures. But previous field experiments have been unable to demonstrate definitively short-latency, mammalian-type physiological thermoregulation. Here we show using telemetered data that free-ranging bigeye tuna (Thunnus obesus) can rapidly alter whole-body thermal conductivity by two orders of magnitude. The heat exchangers are disengaged to allow rapid warming as the tuna ascend from cold water into warmer surface waters, and are reactivated to conserve heat when they return into the depths. Combining physiological and behavioural thermoregulation expands the foraging space of bigeye tuna into otherwise prohibitively cold, deep water. PMID:1641023

  3. Natal homing and connectivity in Atlantic bluefin tuna populations.

    PubMed

    Rooker, Jay R; Secor, David H; De Metrio, Gregorio; Schloesser, Ryan; Block, Barbara A; Neilson, John D

    2008-10-31

    Atlantic bluefin tuna populations are in steep decline, and an improved understanding of connectivity between individuals from eastern (Mediterranean Sea) and western (Gulf of Mexico) spawning areas is needed to manage remaining fisheries. Chemical signatures in the otoliths of yearlings from regional nurseries were distinct and served as natural tags to assess natal homing and mixing. Adults showed high rates of natal homing to both eastern and western spawning areas. Trans-Atlantic movement (east to west) was significant and size-dependent, with individuals of Mediterranean origin mixing with the western population in the U.S. Atlantic. The largest (oldest) bluefin tuna collected near the northern extent of their range in North American waters were almost exclusively of western origin, indicating that this region represents critical habitat for the western population. PMID:18832611

  4. A functional genomics tool for the Pacific bluefin tuna: Development of a 44K oligonucleotide microarray from whole-genome sequencing data for global transcriptome analysis.

    PubMed

    Yasuike, Motoshige; Fujiwara, Atushi; Nakamura, Yoji; Iwasaki, Yuki; Nishiki, Issei; Sugaya, Takuma; Shimizu, Akio; Sano, Motohiko; Kobayashi, Takanori; Ototake, Mitsuru

    2016-02-01

    Bluefin tunas are one of the most important fishery resources worldwide. Because of high market values, bluefin tuna farming has been rapidly growing during recent years. At present, the most common form of the tuna farming is based on the stocking of wild-caught fish. Therefore, concerns have been raised about the negative impact of the tuna farming on wild stocks. Recently, the Pacific bluefin tuna (PBT), Thunnus orientalis, has succeeded in completing the reproduction cycle under aquaculture conditions, but production bottlenecks remain to be solved because of very little biological information on bluefin tunas. Functional genomics approaches promise to rapidly increase our knowledge on biological processes in the bluefin tuna. Here, we describe the development of the first 44K PBT oligonucleotide microarray (oligo-array), based on whole-genome shotgun (WGS) sequencing and large-scale expressed sequence tags (ESTs) data. In addition, we also introduce an initial 44K PBT oligo-array experiment using in vitro grown peripheral blood leukocytes (PBLs) stimulated with immunostimulants such as lipopolysaccharide (LPS: a cell wall component of Gram-negative bacteria) or polyinosinic:polycytidylic acid (poly I:C: a synthetic mimic of viral infection). This pilot 44K PBT oligo-array analysis successfully addressed distinct immune processes between LPS- and poly I:C- stimulated PBLs. Thus, we expect that this oligo-array will provide an excellent opportunity to analyze global gene expression profiles for a better understanding of diseases and stress, as well as for reproduction, development and influence of nutrition on tuna aquaculture production. PMID:26477480

  5. 77 FR 31546 - Atlantic Highly Migratory Species; Atlantic Bluefin Tuna Fisheries

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-29

    ... Species Fishery Management Plan (Consolidated HMS FMP) (71 FR 58058, October 2, 2006) and subsequent... Species; Atlantic Bluefin Tuna Fisheries AGENCY: National Marine Fisheries Service (NMFS), National... area fishery for large medium and giant Atlantic bluefin tuna (BFT) for the remainder of 2012....

  6. 76 FR 38620 - International Fisheries; Atlantic Highly Migratory Species; Bluefin Tuna Import, Export, Re-Export

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-01

    ... fish are tagged) (73 FR 31380, June 2, 2008). Improperly documented bluefin tuna may be prohibited from...; Bluefin Tuna Import, Export, Re-Export AGENCY: National Marine Fisheries Service (NMFS), National Oceanic... commission standards. SUMMARY: Through the International Commission for the Conservation of Atlantic...

  7. Climate effects on historic bluefin tuna captures in the Gibraltar Strait and Western Mediterranean

    NASA Astrophysics Data System (ADS)

    Ganzedo, Unai; Polanco-Martínez, Josué M.; Caballero-Alfonso, Ángela M.; Faria, Sérgio H.; Li, Jianke; Castro-Hernández, José J.

    2016-06-01

    Historical capture records of bluefin tuna (Thunnus thynnus; BFT hereafter) from the Gibraltar Strait and Western Mediterranean show pronounced short- and long-term fluctuations. Some of these fluctuations are believed to be associated with biological and ecological process, as well as distinct climate factors. For the period of study (1700-1936) of this work, we found a long-term increasing trend in the BFT captures and in the climate variables. After applying a statistical time series analysis of relevant climate variables and long-term tuna capture records, it is highlighted the role played by sea-surface temperature (SST) on bluefin population variations. The most relevant result of this study is the strong correlation found between the total solar irradiance (TSI) - an external component of the climate system - and bluefin captures. The solar irradiance could have affected storminess during the period under study, mainly during the time interval 1700-1810. We suggest physico-biological mechanisms that explain the BFT catch fluctuations in two consecutive time intervals. In the first period, from 1700 to 1810, this mechanism could be high storm and wind activity, which would have made the BFT fisheries activities more difficult by reducing their efficacy. In contrast, during the interval from 1810 to 1907, the effects of wind and storms could be on spawning behaviour and larval ecology, and hence on year class strength, rather than on fish or fisherman's behaviour. These findings open up a range of new lines of enquiry that are relevant for both, fisheries and climate change research.

  8. Moving with the beat: heart rate and visceral temperature of free-swimming and feeding bluefin tuna

    PubMed Central

    Clark, T.D; Taylor, B.D; Seymour, R.S; Ellis, D; Buchanan, J; Fitzgibbon, Q.P; Frappell, P.B

    2008-01-01

    Owing to the inherent difficulties of studying bluefin tuna, nothing is known of the cardiovascular function of free-swimming fish. Here, we surgically implanted newly designed data loggers into the visceral cavity of juvenile southern bluefin tuna (Thunnus maccoyii) to measure changes in the heart rate (fH) and visceral temperature (TV) during a two-week feeding regime in sea pens at Port Lincoln, Australia. Fish ranged in body mass from 10 to 21 kg, and water temperature remained at 18–19°C. Pre-feeding fH typically ranged from 20 to 50 beats min−1. Each feeding bout (meal sizes 2–7% of tuna body mass) was characterized by increased levels of activity and fH (up to 130 beats min−1), and a decrease in TV from approximately 20 to 18°C as cold sardines were consumed. The feeding bout was promptly followed by a rapid increase in TV, which signified the beginning of the heat increment of feeding (HIF). The time interval between meal consumption and the completion of HIF ranged from 10 to 24 hours and was strongly correlated with ration size. Although fH generally decreased after its peak during the feeding bout, it remained elevated during the digestive period and returned to routine levels on a similar, but slightly earlier, temporal scale to TV. These data imply a large contribution of fH to the increase in circulatory oxygen transport that is required for digestion. Furthermore, these data oppose the contention that maximum fH is exceptional in bluefin tuna compared with other fishes, and so it is likely that enhanced cardiac stroke volume and blood oxygen carrying capacity are the principal factors allowing superior rates of circulatory oxygen transport in tuna. PMID:18755679

  9. Climate impacts on albacore and bluefin tunas migrations phenology and spatial distribution

    NASA Astrophysics Data System (ADS)

    Dufour, Florence; Arrizabalaga, Haritz; Irigoien, Xabier; Santiago, Josu

    2010-07-01

    North Atlantic albacore and eastern Atlantic bluefin tunas perform feeding migrations to productive areas of the northeast Atlantic Ocean during the summer. Climate change is likely to influence the timing and even the spatial distribution of albacore and bluefin tunas during this event. Thus, tuna catches during their feeding migration to the Bay of Biscay have been analyzed from 1967 to 2005 for albacore tuna and from 1981 to 2005 for bluefin tuna. The results indicate that tuna arrive now earlier to the Bay of Biscay, with albacore tuna arriving about 8 days earlier than 40 years ago and bluefin tuna arriving 14 days earlier than 25 years ago. This represents a rate of change of 2 and 5.6 days per decade, respectively. Besides, albacore tuna mean catch latitude showed an increasing trend over time. Statistical analyses provided the first evidence of the North Atlantic regime shift, as well as climate variability, influencing changes in migration phenology and spatial distribution of albacore and bluefin tunas.

  10. Developmental origin of a major difference in sensory patterning between zebrafish and bluefin tuna.

    PubMed

    Ghysen, Alain; Dambly-Chaudière, Christine; Coves, Denis; de la Gandara, Fernando; Ortega, Aurelio

    2012-01-01

    The posterior lateral line system (PLL) of teleost fish comprises a number of mechanosensory organs arranged in defined patterns on the body surface. Embryonic patterns are largely conserved among teleosts, yet adult patterns are highly diverse. Although changes in pattern modify the perceptual abilities of the system, their developmental origin remains unknown. Here we compare the processes that underlie the formation of the juvenile PLL pattern in Thunnus thynnus, the bluefin tuna, to the processes that were elucidated in Danio rerio, the zebrafish. In both cases, the embryonic PLL comprises five neuromasts regularly spaced along the horizontal myoseptum, but the juvenile PLL comprises four roughly parallel anteroposterior lines in zebrafish, whereas it is a simple dorsally arched line in tuna fish. We examined whether this difference involves evolutionary novelties, and show that the same mechanisms mediate the transition from embryonic to juvenile patterns in both species. We conclude that the marked difference in juveniles depends on a single change (dorsal vs. ventral migration of neuromasts) in the first days of larval life. PMID:23189756

  11. Atlantic Bluefin Tuna: A Novel Multistock Spatial Model for Assessing Population Biomass

    PubMed Central

    Taylor, Nathan G.; McAllister, Murdoch K.; Lawson, Gareth L.; Carruthers, Tom; Block, Barbara A.

    2011-01-01

    Atlantic bluefin tuna (Thunnus thynnus) is considered to be overfished, but the status of its populations has been debated, partly because of uncertainties regarding the effects of mixing on fishing grounds. A better understanding of spatial structure and mixing may help fisheries managers to successfully rebuild populations to sustainable levels while maximizing catches. We formulate a new seasonally and spatially explicit fisheries model that is fitted to conventional and electronic tag data, historic catch-at-age reconstructions, and otolith microchemistry stock-composition data to improve the capacity to assess past, current, and future population sizes of Atlantic bluefin tuna. We apply the model to estimate spatial and temporal mixing of the eastern (Mediterranean) and western (Gulf of Mexico) populations, and to reconstruct abundances from 1950 to 2008. We show that western and eastern populations have been reduced to 17% and 33%, respectively, of 1950 spawning stock biomass levels. Overfishing to below the biomass that produces maximum sustainable yield occurred in the 1960s and the late 1990s for western and eastern populations, respectively. The model predicts that mixing depends on season, ontogeny, and location, and is highest in the western Atlantic. Assuming that future catches are zero, western and eastern populations are predicted to recover to levels at maximum sustainable yield by 2025 and 2015, respectively. However, the western population will not recover with catches of 1750 and 12,900 tonnes (the “rebuilding quotas”) in the western and eastern Atlantic, respectively, with or without closures in the Gulf of Mexico. If future catches are double the rebuilding quotas, then rebuilding of both populations will be compromised. If fishing were to continue in the eastern Atlantic at the unregulated levels of 2007, both stocks would continue to decline. Since populations mix on North Atlantic foraging grounds, successful rebuilding policies will

  12. Atlantic bluefin tuna: a novel multistock spatial model for assessing population biomass.

    PubMed

    Taylor, Nathan G; McAllister, Murdoch K; Lawson, Gareth L; Carruthers, Tom; Block, Barbara A

    2011-01-01

    Atlantic bluefin tuna (Thunnus thynnus) is considered to be overfished, but the status of its populations has been debated, partly because of uncertainties regarding the effects of mixing on fishing grounds. A better understanding of spatial structure and mixing may help fisheries managers to successfully rebuild populations to sustainable levels while maximizing catches. We formulate a new seasonally and spatially explicit fisheries model that is fitted to conventional and electronic tag data, historic catch-at-age reconstructions, and otolith microchemistry stock-composition data to improve the capacity to assess past, current, and future population sizes of Atlantic bluefin tuna. We apply the model to estimate spatial and temporal mixing of the eastern (Mediterranean) and western (Gulf of Mexico) populations, and to reconstruct abundances from 1950 to 2008. We show that western and eastern populations have been reduced to 17% and 33%, respectively, of 1950 spawning stock biomass levels. Overfishing to below the biomass that produces maximum sustainable yield occurred in the 1960s and the late 1990s for western and eastern populations, respectively. The model predicts that mixing depends on season, ontogeny, and location, and is highest in the western Atlantic. Assuming that future catches are zero, western and eastern populations are predicted to recover to levels at maximum sustainable yield by 2025 and 2015, respectively. However, the western population will not recover with catches of 1750 and 12,900 tonnes (the "rebuilding quotas") in the western and eastern Atlantic, respectively, with or without closures in the Gulf of Mexico. If future catches are double the rebuilding quotas, then rebuilding of both populations will be compromised. If fishing were to continue in the eastern Atlantic at the unregulated levels of 2007, both stocks would continue to decline. Since populations mix on North Atlantic foraging grounds, successful rebuilding policies will

  13. Simple measurements reveal the feeding history, the onset of reproduction, and energy conversion efficiencies in captive bluefin tuna

    NASA Astrophysics Data System (ADS)

    Jusup, Marko; Klanjšček, Tin; Matsuda, Hiroyuki

    2014-11-01

    We present a numerical approach that, in conjunction with a fully set up Dynamic Energy Budget (DEB) model, aims at consistently approximating the feeding history of cultivated fish from the commonly measured aquaculture data (body length, body mass, or the condition factor). We demonstrate the usefulness of the approach by performing validation of a DEB-based model for Pacific bluefin tuna (Thunnus orientalis) on an independent dataset and exploring the implied bioenergetics of this species in captivity. In the context of validation, the results indicate that the model successfully accounts for more than 75% of the variance in actual fish feed. At the 5% significance level, predictions do not underestimate nor overestimate observations and there is no bias. The overall model accuracy of 87.6% is satisfactory. In the context of tuna bioenergetics, we offer an explanation as to why the first reproduction in the examined case occurred only after the fish reached seven years of age, whereas it takes five years in the wild and sometimes as little as three years in captivity. Finally, we calculate energy conversion efficiencies and the supply stress throughout the entire lifetime to theoretically underpin the relatively low contribution of growth to aerobic metabolism implied by respirometry and high feed conversion ratio observed in bluefin tuna aquaculture.

  14. Habitat and behaviour of yellowfin tuna Thunnus albacares in the Gulf of Mexico determined using pop-up satellite archival tags.

    PubMed

    Weng, K C; Stokesbury, M J W; Boustany, A M; Seitz, A C; Teo, S L H; Miller, S K; Block, B A

    2009-05-01

    This study presents the first data on movement, habitat use and behaviour for yellowfin tuna Thunnus albacares in the Atlantic Basin. Six individuals were tracked in the Gulf of Mexico using pop-up satellite archival tags. Records up to 80 days in length were obtained, providing information on depth and temperature preferences as well as horizontal movements. Thunnus albacares in the Gulf of Mexico showed a strong preference for the mixed layer and thermocline, consistent with findings for this species in other ocean basins. Fish showed a diel pattern in depth distribution, remaining in surface and mixed layer waters at night and diving to deeper waters during the day. The vertical extent of T. albacares habitat appeared to be temperature limited, with fish generally avoiding waters that were >6 degrees C cooler than surface waters. The vertical and thermal habitat usage of T. albacares differs from that of bigeye Thunnus obesus and bluefin Thunnus thynnus, Thunnus orientalis and Thunnus maccoyii tunas. These results are consistent with the results of earlier studies conducted on T. albacares in other oceans. PMID:20735644

  15. Migratory movements, depth preferences, and thermal biology of Atlantic bluefin tuna.

    PubMed

    Block, B A; Dewar, H; Blackwell, S B; Williams, T D; Prince, E D; Farwell, C J; Boustany, A; Teo, S L; Seitz, A; Walli, A; Fudge, D

    2001-08-17

    The deployment of electronic data storage tags that are surgically implanted or satellite-linked provides marine researchers with new ways to examine the movements, environmental preferences, and physiology of pelagic vertebrates. We report the results obtained from tagging of Atlantic bluefin tuna with implantable archival and pop-up satellite archival tags. The electronic tagging data provide insights into the seasonal movements and environmental preferences of this species. Bluefin tuna dive to depths of >1000 meters and maintain a warm body temperature. Western-tagged bluefin tuna make trans-Atlantic migrations and they frequent spawning grounds in the Gulf of Mexico and eastern Mediterranean. These data are critical for the future management and conservation of bluefin tuna in the Atlantic. PMID:11509729

  16. Reproductive schedules in southern bluefin tuna: are current assumptions appropriate?

    PubMed

    Evans, Karen; Patterson, Toby A; Reid, Howard; Harley, Shelton J

    2012-01-01

    Southern bluefin tuna (SBT) appear to comprise a single stock that is assumed to be both mixed across its distribution and having reproductive adults that are obligate, annual spawners. The putative annual migration cycle of mature SBT consists of dispersed foraging at temperate latitudes with migration to a single spawning ground in the tropical eastern Indian Ocean. Spawning migrations have been assumed to target two peaks in spawning activity; one in September-October and a second in February-March. SBT of sizes comparable to that of individuals observed on the spawning ground were satellite tagged in the Tasman Sea region (2003-2008) and demonstrated both migrations to the spawning grounds and residency in the Tasman Sea region throughout the whole year. All individuals undertaking apparent spawning migrations timed their movements to coincide with the second recognised spawning peak or even later. These observations suggest that SBT may demonstrate substantial flexibility in the scheduling of reproductive events and may even not spawn annually as currently assumed. Further, the population on the spawning grounds may be temporally structured in association with foraging regions. These findings provide new perspectives on bluefin population and spatial dynamics and warrant further investigation and consideration of reproductive schedules in this species. PMID:22514636

  17. Trade-Based Estimation of Bluefin Tuna Catches in the Eastern Atlantic and Mediterranean, 2005–2011

    PubMed Central

    Gagern, Antonius; van den Bergh, Jeroen; Sumaila, Ussif Rashid

    2013-01-01

    The Eastern Atlantic and Mediterranean stock of Bluefin tuna Thunnus thynnus (BFTE) has long been considered overfished and at risk of collapse. Although ICCAT quotas for this stock have decreased considerably over the past years, uncertainty exists about the degree of catch beyond this quota. The extent of such catch is an important piece of information in stock assessment models as well as being an indicator of the effectiveness of fisheries management. We present a model using Bluefin tuna trade data to infer actual catches. Basing our calculations on 25 countries involved in BFTE trade, we estimate that between 2005 and 2011, allowable quotas were exceeded by 44 percent. This gap between catch and quotas has slightly increased over past years, leading to estimated excess catches of 57 percent for the period between 2008 and 2011. To improve assessments, preparation and design of BFTE management, we suggest that the estimated total removals reported in this paper be included in stock assessment models for BFTE. An implication of our findings is that ICCAT member states should take stronger measures to monitor and enforce compliance with quotas. PMID:23922870

  18. 78 FR 11788 - Atlantic Highly Migratory Species; Atlantic Bluefin Tuna Fisheries; General Category Fishery

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-20

    ... Species Fishery Management Plan (Consolidated HMS FMP) (71 FR 58058, October 2, 2006) and subsequent... Species; Atlantic Bluefin Tuna Fisheries; General Category Fishery AGENCY: National Marine Fisheries... tuna (BFT) until the General category reopens on June 1, 2013. This action is being taken to...

  19. 77 FR 3637 - Atlantic Highly Migratory Species; Atlantic Bluefin Tuna Fisheries; General Category Fishery

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-25

    ... Highly Migratory Species Fishery Management Plan (Consolidated HMS FMP) (71 FR 58058, October 2, 2006... Species; Atlantic Bluefin Tuna Fisheries; General Category Fishery AGENCY: National Marine Fisheries... tuna (BFT) until the General category reopens on June 1, 2012. This action is being taken to...

  20. Reconstructing transoceanic migration patterns of Pacific bluefin tuna using a chemical tracer toolbox.

    PubMed

    Madigan, Daniel J; Baumann, Zofia; Carlisle, Aaron B; Hoen, Danielle K; Popp, Brian N; Dewar, Heidi; Snodgrass, Owyn E; Block, Barbara A; Fisher, Nicholas S

    2014-06-01

    Large pelagic predators play important roles in oceanic ecosystems, and may migrate vast distances to utilize resources in different marine ecoregions. Understanding movement patterns of migratory marine animals is critical for effective management, but often challenging, due to the cryptic habitat of pelagic migrators and the difficulty of assessing past movements. Chemical tracers can partially circumvent these challenges by reconstructing recent migration patterns. Pacific bluefin tuna (Thunnus orientalis; PBFT) inhabit the western and eastern Pacific Ocean, and are in steep decline due to overfishing. Understanding age-specific eastward transpacific migration patterns can improve management practices, but these migratory dynamics remain largely unquantified. Here, we combine a Fukushima-derived radiotracer (134Cs) with bulk tissue and amino acid stable isotope analyses of PBFT to distinguish recent migrants from residents of the eastern Pacific Ocean. The proportion of recent migrants to residents decreased in older year classes, though the proportion of older PBFT that recently migrated across the Pacific was greater than previous estimates. This novel toolbox of biogeochemical tracers can be applied to any species that crosses the North Pacific Ocean. PMID:25039231

  1. Estimating diets of pre-spawning Atlantic bluefin tuna from stomach content and stable isotope analyses

    NASA Astrophysics Data System (ADS)

    Varela, José L.; Rodríguez-Marín, Enrique; Medina, Antonio

    2013-02-01

    Stomach content analysis (SCA) and stable isotope analysis (SIA) coupled with isotopic mixing model analysis were used to estimate diet composition of pre-spawning Atlantic bluefin tuna (ABFT), Thunnus thynnus, caught by trap in the Strait of Gibraltar area. SCA provided poor information on diet as most of the stomachs appeared empty or contained only hard remains. Mixing model diet compositions estimated from muscle tissue SIA data did not show clear inter-annual variations and suggested that ABFT fed on prey that occupy high and intermediate level positions of the food web. Otherwise, diet compositions estimated from liver tissue SIA showed greater inter-annual variations and appeared to indicate that ABFT fed on prey located at lower trophic levels. The different dietary compositions inferred from muscle and liver samples were most probably due to the different turnover rates of these organs, which would provide trophic information at two distinct time scales. Our findings suggest that a combination of SCA and SIA is more suitable than using SCA alone to determine temporal and regional variations in ABFT diet composition.

  2. Autoxidation of myoglobin from bigeye tuna fish (Thunnus obesus).

    PubMed

    Kitahara, Y; Matsuoka, A; Kobayashi, N; Shikama, K

    1990-03-29

    Native oxymyoglobin (MbO2) was isolated directly from the skeletal muscle of bigeye tuna (Thunnus obesus) with complete separation from metmyoglobin (metMb) on a CM-cellulose column. It was examined for its stability properties over a wide range of pH values (pH 5-12) in 0.1 M buffer at 25 degrees C. When compared with sperm whale MbO2 as a reference, the tuna MbO2 was found to be much more susceptible to autoxidation. Kinetic analysis has revealed that the rate constant for a nucleophilic displacement of O2- from MbO2 by an entering water molecule is 10-times higher than the corresponding value for sperm whale MbO2. The magnitude of the circular dichroism of bigeye tuna myoglobin at 222 nm was comparable to that of sperm whale myoglobin, but its hydropathy profile revealed the region corresponding to the distal side of the heme iron to be apparently less hydrophobic. The kinetic simulation also demonstrated that accessibility of the solvent water molecule to the heme pocket is clearly a key factor in the stability properties of the bound dioxygen. PMID:2317515

  3. Depressed resilience of bluefin tuna in the western atlantic and age truncation.

    PubMed

    Secor, D H; Rooker, J R; Gahagan, B I; Siskey, M R; Wingate, R W

    2015-04-01

    Following intense overfishing in the 1970s, the western stock of Atlantic bluefin tuna (Thunnus thynnus) experienced a long period of depressed abundance, which has been attributed to failure of the population to periodically produce large numbers of juveniles, the western stock mixing with the more highly exploited eastern stock (fisheries in the Northeast Atlantic Ocean and Mediterranean Sea), and regime shift in the population's ecosystem resulting in lower replacement rates. To evaluate the presence of relatively strong years of juvenile production, we analyzed age structure from a recent sample of otoliths (ear stones) collected from the western stock (2011-2013, North Carolina, U.S.A., winter fishery). Mixing levels for the recent sample were analyzed using otolith stable isotopes to test whether age structure might be biased through immigration of eastern stock bluefin tuna. Age structure from historical samples collected from United States and Canadian fisheries (1975-1981) was compared with more recent samples (1996-2007) to examine whether demographic changes had occurred to the western stock that might have disrupted juvenile production. Relatively high juvenile production occurred in 2003, 2005, and 2006. Otolith stable isotope analysis showed that these recruitments were mostly of western stock origin. However, these high recruitments were >2-fold less than historical recruitment. We found substantial age truncation in the sampled fisheries. Half the historical sample was >20 years old (mean age = 20.1 [SD 3.7]; skewness = -0.3), whereas <5% of the recent sample was >20 years old (mean age = 13.4 [SD 3.8]; skewness = 1.3). Loss of age structure is consistent with changes in fishing selectivity and trends in the stock assessment used for management. We propose that fishing, as a forcing variable, brought about a threshold shift in the western stock toward lower biomass and production, a shift that emulates the regime shift hypothesis. An abbreviated

  4. Habitat suitability of the Atlantic bluefin tuna by size class: An ecological niche approach

    NASA Astrophysics Data System (ADS)

    Druon, Jean-Noël; Fromentin, Jean-Marc; Hanke, Alex R.; Arrizabalaga, Haritz; Damalas, Dimitrios; Tičina, Vjekoslav; Quílez-Badia, Gemma; Ramirez, Karina; Arregui, Igor; Tserpes, George; Reglero, Patricia; Deflorio, Michele; Oray, Isik; Saadet Karakulak, F.; Megalofonou, Persefoni; Ceyhan, Tevfik; Grubišić, Leon; MacKenzie, Brian R.; Lamkin, John; Afonso, Pedro; Addis, Piero

    2016-03-01

    An ecological niche modelling (ENM) approach was used to predict the potential feeding and spawning habitats of small (5-25 kg, only feeding) and large (>25 kg) Atlantic bluefin tuna (ABFT), Thunnus thynnus, in the Mediterranean Sea, the North Atlantic and the Gulf of Mexico. The ENM was built bridging knowledge on ecological traits of ABFT (e.g. temperature tolerance, mobility, feeding and spawning strategy) with patterns of selected environmental variables (chlorophyll-a fronts and concentration, sea surface current and temperature, sea surface height anomaly) that were identified using an extensive set of precisely geo-located presence data. The results highlight a wider temperature tolerance for larger fish allowing them to feed in the northern - high chlorophyll levels - latitudes up to the Norwegian Sea in the eastern Atlantic and to the Gulf of Saint Lawrence in the western basin. Permanent suitable feeding habitat for small ABFT was predicted to be mostly located in temperate latitudes in the North Atlantic and in the Mediterranean Sea, as well as in subtropical waters off north-west Africa, while summer potential habitat in the Gulf of Mexico was found to be unsuitable for both small and large ABFTs. Potential spawning grounds were found to occur in the Gulf of Mexico from March-April in the south-east to April-May in the north, while favourable conditions evolve in the Mediterranean Sea from mid-May in the eastern to mid-July in the western basin. Other secondary potential spawning grounds not supported by observations were predicted in the Azores area and off Morocco to Senegal during July and August when extrapolating the model settings from the Gulf of Mexico into the North Atlantic. The presence of large ABFT off Florida and the Bahamas in spring was not explained by the model as is, however the environmental variables other than the sea surface height anomaly appeared to be favourable for spawning in part of this area. Defining key spatial and

  5. Mitochondrial genome of the blackfin tuna Thunnus atlanticus Lesson, 1831 (Perciformes, Scrombidae).

    PubMed

    Márquez, Edna J; Isaza, Juan P; Alzate, Juan F

    2016-05-01

    Blackfin tuna, Thunnus atlanticus is a widespread epipelagic oceanic species in the western Atlantic. So far the mitochondrial genome of this species remained unknown, although the mitogenomes of all congeners are known. The mitochondrial genome encodes for 13 proteins, 21 tRNAs, 2 ribosomal RNAs and the gene synteny is conserved with other previously reported mitogenomes of tunas. PMID:25269003

  6. Discovery of intermediate hosts for two species of blood flukes Cardicola orientalis and Cardicola forsteri (Trematoda: Aporocotylidae) infecting Pacific bluefin tuna in Japan.

    PubMed

    Shirakashi, Sho; Tani, Kazuki; Ishimaru, Katsuya; Shin, Sang Phil; Honryo, Tomoki; Uchida, Hiro'omi; Ogawa, Kazuo

    2016-04-01

    Fish blood flukes (Aporocotylidae) are important pathogens of farmed finfish around the world. Among them, Cardicola spp. infecting farmed tuna are considered to be serious threats to tuna farming and have received tremendous attention. We conducted periodical samplings at a tuna farming site in Japan between January and May, 2015 to determine the life cycle of Cardicola spp. We collected over 4700 terebellid polychaetes from ropes, floats and frames of tuna culture cages and found nearly 400 infected worms. Sporocysts and cercariae found in Nicolea gracilibranchis were genetically identified as Cardicola orientalis by 28S and ITS2 ribosomal DNA sequences. This was the first discovery of the intermediate host for this parasite species. Infection prevalence and the abundance of N. gracilibranchis significantly varied between sampling points and the highest number of infected terebellids were collected from ropes. We also demonstrated morphologically and molecularly that asexual stages found in a single Amphitrite sp. (Terebellidae) and adult worms isolated from farmed juvenile tuna were Cardicola forsteri. This is the first report of C. forsteri in Pacific bluefin tuna (PBT) Thunnus orientalis in Japan. Our results demonstrated that all three species of Cardicola orientalis, C. forsteri and Cardicola opisthorchis exist in Japanese farmed PBTs and that they all use terebellid polychaetes as the intermediate hosts. PMID:26571413

  7. Temperature sensitivity of cardiac function in pelagic fishes with different vertical mobilities: yellowfin tuna (Thunnus albacares), bigeye tuna (Thunnus obesus), mahimahi (Coryphaena hippurus), and swordfish (Xiphias gladius).

    PubMed

    Galli, Gina L J; Shiels, Holly A; Brill, Richard W

    2009-01-01

    We measured the temperature sensitivity, adrenergic sensitivity, and dependence on sarcoplasmic reticulum (SR) Ca(2+) of ventricular muscle from pelagic fishes with different vertical mobility patterns: bigeye tuna (Thunnus obesus), yellowfin tuna (Thunnus albacares), and mahimahi (Coryphaena hippurus) and a single specimen from swordfish (Xiphias gladius). Ventricular muscle from the bigeye tuna and mahimahi exhibited a biphasic response to an acute decrease in temperature (from 26 degrees to 7 degrees C); twitch force and kinetic parameters initially increased and then declined. The magnitude of this response was larger in the bigeye tuna than in the mahimahi. Under steady state conditions at 26 degrees C, inhibition of SR Ca(2+) release and reuptake with ryanodine and thapsigargin decreased twitch force and kinetic parameters, respectively, in the bigeye tuna only. However, the initial inotropy associated with decreasing temperature was abolished by SR inhibition in both the bigeye tuna and the mahimahi. Application of adrenaline completely reversed the effects of ryanodine and thapsigargin, but this effect was diminished at cold temperatures. In the yellowfin tuna, temperature and SR inhibition had minor effects on twitch force and kinetics, while adrenaline significantly increased these parameters. Limited data suggest that swordfish ventricular muscle responds to acute temperature reduction, SR inhibition, and adrenergic stimulation in a manner similar to that of bigeye tuna ventricular muscle. In aggregate, our results show that the temperature sensitivity, SR dependence, and adrenergic sensitivity of pelagic fish hearts are species specific and that these differences reflect species-specific vertical mobility patterns. PMID:19284308

  8. 50 CFR 300.211 - Definitions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... alalunga. Pacific bluefin tuna Thunnus orientalis. Southern bluefin tuna Thunnus maccoyii. Bigeye tuna Thunnus obesus. Skipjack tuna Katsuwonus pelamis. Yellowfin tuna Thunnus albacares. Little tuna...

  9. Do fattening process and biological parameters affect the accumulation of metals in Atlantic bluefin tuna?

    PubMed

    Milatou, Niki; Dassenakis, Manos; Megalofonou, Persefoni

    2015-01-01

    The objective of this study was to determine the current levels of heavy metals and trace elements in Atlantic bluefin tuna muscle tissues and how they are influenced by the fattening process and various life history parameters to ascertain whether the concentrations in muscle tissue exceed the maximum levels defined by the European Commission Decision and to evaluate the health risk posed by fish consumption. A total of 20 bluefin tuna reared in sea cages, ranging from 160 to 295 cm in length and from 80 to 540 kg in weight, were sampled from a bluefin tuna farm in the Ionian Sea. The condition factor K of each specimen was calculated and their age was estimated. Heavy metal and trace element (Hg, Zn, Fe and Cu) contents were determined in muscle tissue using cold vapour atomic absorption spectrometry and flame and graphite furnace atomic absorption spectrometry. The total Hg concentrations ranged from 0.28 to 1.28 mg kg(-1) w/w, Zn from 5.81 to 76.37 mg kg(-1) w/w, Fe from 12.14 to 39.58 mg kg(-1) w/w, and Cu from 0.36 to 0.94 mg kg(-1) w/w. Only 5% of the muscle samples of tuna contained Hg above the maximum level laid down by the European Commission Decision. Moreover, 15% of the muscle samples contained Zn above the maximum level, while Fe and Cu concentrations were within the acceptable tolerable guideline values. The reared bluefin tuna had lower concentrations of Hg than the wild ones from the Mediterranean Sea. Hg and Fe concentrations showed a positive relationship with size and age of bluefin tuna, whereas negative relationships were found for the concentrations of Zn and Cu. The estimated dietary intake values of the analysed metals were mostly below the derived guidelines. PMID:25906290

  10. 75 FR 33731 - Atlantic Highly Migratory Species; 2010 Atlantic Bluefin Tuna Quota Specifications

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-15

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration 50 CFR Part 635 RIN 0648-AY77 Atlantic Highly Migratory Species; 2010 Atlantic Bluefin Tuna Quota Specifications Correction In rule document 2010-13207...

  11. 77 FR 38011 - Atlantic Highly Migratory Species; Atlantic Bluefin Tuna Fisheries

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-26

    ... FMP) (71 FR 58058, October 2, 2006) and subsequent rulemaking. Under Sec. 635.27(a)(3), the total... announced a closure of the Longline category southern area BFT fishery, effective May 29, 2012 (77 FR 31546... Species; Atlantic Bluefin Tuna Fisheries AGENCY: National Marine Fisheries Service (NMFS),...

  12. 75 FR 33531 - Atlantic Highly Migratory Species; Atlantic Bluefin Tuna Fisheries

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-14

    ... Consolidated HMS FMP) (71 FR 58058, October 2, 2006). The 2010 BFT fishing year, which is managed on a calendar... categories (75 FR 30732, June 2, 2010). The final 2010 Angling category quota is 225.4 mt (97.7 mt for school... Species; Atlantic Bluefin Tuna Fisheries AGENCY: National Marine Fisheries Service (NMFS),...

  13. 77 FR 21015 - Atlantic Highly Migratory Species; Atlantic Bluefin Tuna Fisheries

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-09

    ... categories, per the allocations established in the Consolidated HMS FMP (71 FR 58058, October 2, 2006) and in... remainder of the respective fishing years (75 FR 33531, June 14, 2010, and 76 FR 18416, April 4, 2011... Species; Atlantic Bluefin Tuna Fisheries AGENCY: National Marine Fisheries Service (NMFS),...

  14. Comparative influence of ocean conditions on yellowfin and Atlantic bluefin tuna catch from longlines in the Gulf of Mexico.

    PubMed

    Teo, Steven L H; Block, Barbara A

    2010-01-01

    Directed fishing effort for Atlantic bluefin tuna in the Gulf of Mexico (GOM), their primary spawning grounds in the western Atlantic, has been prohibited since the 1980s due to a precipitous decline of the spawning stock biomass. However, pelagic longlines targeted at other species, primarily yellowfin tuna and swordfish, continue to catch Atlantic bluefin tuna in the GOM as bycatch. Spatial and temporal management measures minimizing bluefin tuna bycatch in the GOM will likely become important in rebuilding the western Atlantic bluefin stock. In order to help inform management policy and understand the relative distribution of target and bycatch species in the GOM, we compared the spatiotemporal variability and environmental influences on the catch per unit effort (CPUE) of yellowfin (target) and bluefin tuna (bycatch). Catch and effort data from pelagic longline fisheries observers (1993-2005) and scientific tagging cruises (1998-2002) were coupled with environmental and biological data. Negative binomial models were used to fit the data for both species and Akaike's Information Criterion (corrected for small sample size) was used to determine the best model. Our results indicate that bluefin CPUE had higher spatiotemporal variability as compared to yellowfin CPUE. Bluefin CPUE increased substantially during the breeding months (March-June) and peaked in April and May, while yellowfin CPUE remained relatively high throughout the year. In addition, bluefin CPUE was significantly higher in areas with negative sea surface height anomalies and cooler sea surface temperatures, which are characteristic of mesoscale cyclonic eddies. In contrast, yellowfin CPUE was less sensitive to environmental variability. These differences in seasonal variability and sensitivity to environmental influences suggest that bluefin tuna bycatch in the GOM can be reduced substantially by managing the spatial and temporal distribution of the pelagic longline effort without substantially

  15. Comparative Influence of Ocean Conditions on Yellowfin and Atlantic Bluefin Tuna Catch from Longlines in the Gulf of Mexico

    PubMed Central

    Teo, Steven L. H.; Block, Barbara A.

    2010-01-01

    Directed fishing effort for Atlantic bluefin tuna in the Gulf of Mexico (GOM), their primary spawning grounds in the western Atlantic, has been prohibited since the 1980s due to a precipitous decline of the spawning stock biomass. However, pelagic longlines targeted at other species, primarily yellowfin tuna and swordfish, continue to catch Atlantic bluefin tuna in the GOM as bycatch. Spatial and temporal management measures minimizing bluefin tuna bycatch in the GOM will likely become important in rebuilding the western Atlantic bluefin stock. In order to help inform management policy and understand the relative distribution of target and bycatch species in the GOM, we compared the spatiotemporal variability and environmental influences on the catch per unit effort (CPUE) of yellowfin (target) and bluefin tuna (bycatch). Catch and effort data from pelagic longline fisheries observers (1993–2005) and scientific tagging cruises (1998–2002) were coupled with environmental and biological data. Negative binomial models were used to fit the data for both species and Akaike's Information Criterion (corrected for small sample size) was used to determine the best model. Our results indicate that bluefin CPUE had higher spatiotemporal variability as compared to yellowfin CPUE. Bluefin CPUE increased substantially during the breeding months (March-June) and peaked in April and May, while yellowfin CPUE remained relatively high throughout the year. In addition, bluefin CPUE was significantly higher in areas with negative sea surface height anomalies and cooler sea surface temperatures, which are characteristic of mesoscale cyclonic eddies. In contrast, yellowfin CPUE was less sensitive to environmental variability. These differences in seasonal variability and sensitivity to environmental influences suggest that bluefin tuna bycatch in the GOM can be reduced substantially by managing the spatial and temporal distribution of the pelagic longline effort without

  16. Co-Occurrence and Habitat Use of Fin Whales, Striped Dolphins and Atlantic Bluefin Tuna in the Northwestern Mediterranean Sea.

    PubMed

    Bauer, Robert Klaus; Fromentin, Jean-Marc; Demarcq, Hervé; Brisset, Blandine; Bonhommeau, Sylvain

    2015-01-01

    Different dolphin and tuna species have frequently been reported to aggregate in areas of high frontal activity, sometimes developing close multi-species associations to increase feeding success. Aerial surveys are a common tool to monitor the density and abundance of marine mammals, and have recently become a focus in the search for methods to provide fisheries-independent abundance indicators for tuna stock assessment. In this study, we present first density estimates corrected for availability bias of fin whales (Balaenoptera physalus) and striped dolphins (Stenella coeruleoalba) from the Golf of Lions (GoL), compared with uncorrected estimates of Atlantic bluefin tuna (ABFT; Thunnus thynnus) densities from 8 years of line transect aerial surveys. The raw sighting data were further used to analyze patterns of spatial co-occurrence and density of these three top marine predators in this important feeding ground in the Northwestern Mediterranean Sea. These patterns were investigated regarding known species-specific feeding preferences and environmental characteristics (i. e. mesoscale activity) of the survey zone. ABFT was by far the most abundant species during the surveys in terms of schools and individuals, followed by striped dolphins and fin whales. However, when accounted for availability bias, schools of dolphins and fin whales were of equal density. Direct interactions of the species appeared to be the exception, but results indicate that densities, presence and core sighting locations of striped dolphins and ABFT were correlated. Core sighting areas of these species were located close to an area of high mesoscale activity (oceanic fronts and eddies). Fin whales did not show such a correlation. The results further highlight the feasibility to coordinate research efforts to explore the behaviour and abundance of the investigated species, as demanded by the Marine Strategy Framework Directive (MSFD). PMID:26458254

  17. Co-Occurrence and Habitat Use of Fin Whales, Striped Dolphins and Atlantic Bluefin Tuna in the Northwestern Mediterranean Sea

    PubMed Central

    Bauer, Robert Klaus; Demarcq, Hervé; Brisset, Blandine

    2015-01-01

    Different dolphin and tuna species have frequently been reported to aggregate in areas of high frontal activity, sometimes developing close multi-species associations to increase feeding success. Aerial surveys are a common tool to monitor the density and abundance of marine mammals, and have recently become a focus in the search for methods to provide fisheries-independent abundance indicators for tuna stock assessment. In this study, we present first density estimates corrected for availability bias of fin whales (Balaenoptera physalus) and striped dolphins (Stenella coeruleoalba) from the Golf of Lions (GoL), compared with uncorrected estimates of Atlantic bluefin tuna (ABFT; Thunnus thynnus) densities from 8 years of line transect aerial surveys. The raw sighting data were further used to analyze patterns of spatial co-occurrence and density of these three top marine predators in this important feeding ground in the Northwestern Mediterranean Sea. These patterns were investigated regarding known species-specific feeding preferences and environmental characteristics (i. e. mesoscale activity) of the survey zone. ABFT was by far the most abundant species during the surveys in terms of schools and individuals, followed by striped dolphins and fin whales. However, when accounted for availability bias, schools of dolphins and fin whales were of equal density. Direct interactions of the species appeared to be the exception, but results indicate that densities, presence and core sighting locations of striped dolphins and ABFT were correlated. Core sighting areas of these species were located close to an area of high mesoscale activity (oceanic fronts and eddies). Fin whales did not show such a correlation. The results further highlight the feasibility to coordinate research efforts to explore the behaviour and abundance of the investigated species, as demanded by the Marine Strategy Framework Directive (MSFD). PMID:26458254

  18. Organic waste impact of capture-based Atlantic bluefin tuna aquaculture at an exposed site in the Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Vezzulli, Luigi; Moreno, Mariapaola; Marin, Valentina; Pezzati, Elisabetta; Bartoli, Marco; Fabiano, Mauro

    2008-06-01

    A variety of pelagic and benthic parameters were measured at an aquaculture farm used for the fattening of Atlantic bluefin tuna ( Thunnus thynnus) which is located at an exposed site (700 m from the coast, average bottom depth of 45 m and average current speed of 6 cm s -1) in the Mediterranean Sea. The objective was to test whether modern off-shore tuna fattening industries can exert a sustainable organic waste impact on the receiving environment as has been reported for the offshore culture of more traditional Mediterranean species such as sparids. In the water column, the concentration of phytopigments, organic matter, heterotrophic bacteria and the taxonomic abundance of mesozooplankton (at the species level) were assessed. In the sediment, we assessed the concentration of reduced sulphur pools, phytopigments, organic matter, heterotrophic bacteria and the taxonomic abundance of meiofauna (at the taxa level) and nematodes (at the genus level). For most parameters, we found no substantial differences between farm and control sites. Deviations of farm values from control values, when they occurred, were small and did not indicate any significant impact on either the pelagic and benthic environment. Deviations were more apparent in the benthic compartment where lower redox potential values, higher bacterial production rates and a change in nematode genus composition pointed out to early changes in the sediment's metabolism. In addition, indigenous potential pathogenic bacteria showed higher concentration at the fish farm stations and were a warning of an undesirable event that may become established following aquaculture practice in oligotrophic environments. The overall data from this study provide extensive experimental evidence to support the sustainability of modern offshore farming technology in minimizing the hypertrophic-dystrophic risks associated with the rapidly-expanding tuna-fattening industry in the Mediterranean Sea.

  19. Characterization of the Boundary Layer on Full-Scale Bluefin Tuna

    NASA Astrophysics Data System (ADS)

    Amaral, Brian; Cipolla, Kimberly; Henoch, Charles

    2014-11-01

    The physics that enable tuna to cross large expanses of ocean while feeding and avoiding predators is not presently understood, and could involve complex control of turbulent boundary layer transition and drag reduction. Typical swimming speeds of Bluefin tuna are 1-2 m/s, but can be higher during strong accelerations. The goal of this work is to experimentally determine the approximate lateral location at which transition to turbulence occurs on the tuna for various speeds. The question is whether laminar flow or an advanced propulsion mechanism (or both) allows them to swim at high speeds. Uncertainties include the surface roughness of the skin, local favorable and adverse pressure gradients, and discontinuities such as the open mouth or juncture at the fins. Historically, much of the fluid mechanics work in the area of fish locomotion has focused on vortex shedding issues rather than the boundary layer. Here, the focus is obtaining information on the boundary layer characteristics of a rigid tuna model. A full scale model of a Pacific Bluefin tuna was fabricated using a mold made from an actual deceased tuna, preserving the surface features and details of the appendages. The model was instrumented with 32 wall pressure sensors and experiments performed in a tow tank. Results from flow visualization, drag and wall pressure measurements over a range of speeds and varying angles of attack will be presented.

  20. Trypsins from yellowfin tuna (Thunnus albacores) spleen: purification and characterization.

    PubMed

    Klomklao, Sappasith; Benjakul, Soottawat; Visessanguan, Wonnop; Kishimura, Hideki; Simpson, Benjamin K; Saeki, Hiroki

    2006-05-01

    Two anionic trypsins (A and B) were purified to homogeneity from yellowfin tuna (Thunnus albacores) spleen by a series of column chromatographies including Sephacryl S-200, Sephadex G-50 and DEAE-cellulose. Purity was increased to 70.6- and 91.5-fold with approximately 2.8% and 15.6% yield for trypsin A and B, respectively. The apparent molecular weight of both trypsins was estimated to be 24 kDa by size exclusion chromatography and SDS-PAGE. Both trypsin A and B appeared as a single band on native-PAGE. Trypsin A and B exhibited the maximal activity at 55 and 65 degrees C, respectively, and had the same optimal pH at 8.5 using TAME as a substrate. Both trypsins were stable to heat treatment up to 50 degrees C and in the pH range of 6.0 to 11.0. Both trypsin A and B were stabilized by calcium ion. The activities were inhibited effectively by soybean trypsin inhibitor, TLCK and partially inhibited by EDTA, but were not inhibited by E-64, N-ethylmaleimide, iodoacetic acid, TPCK and pepstatin A. Activity of both trypsins continuously decreased with increasing NaCl concentration (0-30%). Apparent Km and Kcat of trypsin A and B for TAME were 0.2-0.33 mM and 66.7-80 S(-1), respectively. The N-terminal amino acid sequences of trypsin A, IVGGYECQAHSQPHQVSLNA, and trypsin B, IVGGYECQAHSQPPQVSLNA, indicated the high homology between both enzymes. PMID:16500127

  1. Spatio-temporal population structuring and genetic diversity retention in depleted Atlantic bluefin tuna of the Mediterranean Sea.

    PubMed

    Riccioni, Giulia; Landi, Monica; Ferrara, Giorgia; Milano, Ilaria; Cariani, Alessia; Zane, Lorenzo; Sella, Massimo; Barbujani, Guido; Tinti, Fausto

    2010-02-01

    Fishery genetics have greatly changed our understanding of population dynamics and structuring in marine fish. In this study, we show that the Atlantic Bluefin tuna (ABFT, Thunnus thynnus), an oceanic predatory species exhibiting highly migratory behavior, large population size, and high potential for dispersal during early life stages, displays significant genetic differences over space and time, both at the fine and large scales of variation. We compared microsatellite variation of contemporary (n = 256) and historical (n = 99) biological samples of ABFTs of the central-western Mediterranean Sea, the latter dating back to the early 20th century. Measures of genetic differentiation and a general heterozygote deficit suggest that differences exist among population samples, both now and 96-80 years ago. Thus, ABFTs do not represent a single panmictic population in the Mediterranean Sea. Statistics designed to infer changes in population size, both from current and past genetic variation, suggest that some Mediterranean ABFT populations, although still not severely reduced in their genetic potential, might have suffered from demographic declines. The short-term estimates of effective population size are straddled on the minimum threshold (effective population size = 500) indicated to maintain genetic diversity and evolutionary potential across several generations in natural populations. PMID:20080643

  2. Environmental forcing and the larval fish community associated to the Atlantic bluefin tuna spawning habitat of the Balearic region (Western Mediterranean), in early summer 2005

    NASA Astrophysics Data System (ADS)

    Rodriguez, J. M.; Alvarez, I.; Lopez-Jurado, J. L.; Garcia, A.; Balbin, R.; Alvarez-Berastegui, D.; Torres, A. P.; Alemany, F.

    2013-07-01

    The Balearic region is a highly dynamic area located in the Western Mediterranean, straddling the transition between the Algerian and Provencal basins and constitutes one of the main spawning grounds for the large, migratory Atlantic bluefin (Thunnus thynnus) and other medium and small tuna species (Thunnus alalunga, Auxis rochei, Euthynnus alleteratus and Katsuwonus pelamis). In summer, despite been considered an oligotrophic region as the whole Mediterranean Sea, it harbors a relatively abundant and diverse larval fish community (LFC). In this study, we analyze the composition, abundance and the influence of abiotic and biotic factors on the horizontal structure of the LFC in the Balearic region, in early summer 2005, during the spawning season of Atlantic bluefin tuna. Hydrographically, 2005 was an unusual year with a summer situation of relatively lack of mesoscale features, weak surface currents and a general situation of high stability. A total of 128 taxa of fish larvae, belonging to 52 families, were identified. The average abundance was 1770 larvae 1000 m-3. Multivariate statistical analysis revealed LFC to have a strong horizontal structure. Cluster analysis and non-metric multidimensional scaling ordination identified two larval fish assemblages. These assemblages were mainly delineated by depth and, therefore, by the spawning location of adult fish. Our results also suggest that anticyclonic eddy boundaries constitute favourable habitats for fish larvae. Also, the scenario of higher than unusual hydrographic stability found during the cruise would be responsible for the relatively lack of mesoscale features and, consequently, for the lack of influence of these features on the horizontal distribution of fish larvae and on the horizontal structure of the LFC.

  3. DNA barcodes reveal species-specific mercury levels in tuna sushi that pose a health risk to consumers.

    PubMed

    Lowenstein, Jacob H; Burger, Joanna; Jeitner, Christian W; Amato, George; Kolokotronis, Sergios-Orestis; Gochfeld, Michael

    2010-10-23

    Excessive ingestion of mercury--a health hazard associated with consuming predatory fishes--damages neurological, sensory-motor and cardiovascular functioning. The mercury levels found in Bigeye Tuna (Thunnus obesus) and bluefin tuna species (Thunnus maccoyii, Thunnus orientalis, and Thunnus thynnus), exceed or approach levels permissible by Canada, the European Union, Japan, the US, and the World Health Organization. We used DNA barcodes to identify tuna sushi samples analysed for mercury and demonstrate that the ability to identify cryptic samples in the market place allows regulatory agencies to more accurately measure the risk faced by fish consumers and enact policies that better safeguard their health. PMID:20410032

  4. Total and organic mercury concentrations in the muscles of Pacific albacore (Thunnus alalunga) and bigeye tuna (Thunnus obesus).

    PubMed

    Chen, Chiee-Young; Lai, Chien-Cheng; Chen, Kuo-Shu; Hsu, Chien-Chung; Hung, Chin-Chang; Chen, Meng-Hsien

    2014-08-30

    Muscles of 115 North Pacific albacore (ALB, Thunnus alalunga) and 75 Pacific bigeye tuna (BET, Thunnus obesus), collected from 2001 to 2006, were analyzed. No ALB, but 13 large BET had organic mercury (OH g) concentrations exceeding 1 μg g(-1) wet weight. For both ALB and BET, total mercury (THg) and OH g concentrations were significantly and positively correlated with fork length (FL) and body weight. The muscle Hg bioaccumulation rates of BET were higher than those of ALB, particularly in the adult fish. Moreover, the lines had crossover points among the two species that imply the young BET (FL<110 cm) contains lower muscle Hg concentrations than ALB of the same size. The suggested weekly dietary intake of ALB and small-BET meats is 340 g, and of BET meat it is 150 g for a 60-kg person based on the provisional tolerable weekly intake (PTWI) of methylmercury set by the WHO. PMID:24559740

  5. Polychlorinated biphenyls and organochlorine pesticides as intrinsic tracer tags of foraging grounds of bluefin tuna in the northwest Atlantic Ocean.

    PubMed

    Deshpande, Ashok D; Dickhut, Rebecca M; Dockum, Bruce W; Brill, Richard W; Farrington, Cameron

    2016-04-15

    Researchers have utilized chemical fingerprints in the determination of habitat utilization and movements of the aquatic animals. In the present effort, we analyzed polychlorinated biphenyl (PCB) congeners and organochlorine pesticides in the samples of juvenile bluefin tuna caught offshore of Virginia, and in larger bluefin tuna from the Gulf of Maine and near Nova Scotia. For a given specimen, or a given location, PCB concentrations were highest, followed by DDTs, and chlordanes. Average contaminant concentrations from fish captured from the three locations were not significantly different; and PCBs, DDTs, and chlordanes correlated well with each other. Trans-nonachlor/PCB 153 ratios in bluefin tuna of eastern Atlantic (i.e., Mediterranean) origin are low compared to the corresponding ratios in fish in the western Atlantic. As the former migrate to the western Atlantic, these ratios gradually turnover due to the accumulation of biomass from forage contaminated with higher trans-nonachlor/PCB 153 ratio reflecting dissimilar use of chlordane pesticides on two sides of the Atlantic Ocean. The trans-nonachlor/PCB 153 ratio indicated that one juvenile bluefin tuna from offshore of Virginia and one large bluefin tuna from Gulf of Maine in the present study originated from foraging grounds in the Mediterranean Sea, and that they have made the trans-Atlantic migrations. The remaining individuals were determined to be either spawned in the Gulf of Mexico or the trans-nonachlor/PCB 153 ratio for the putative Mediterranean bluefin tuna was completely turned over to resemble the ratio characteristic to the western Atlantic. Based on the turnover time for trans-nonachlor/PCB 153 ratio previously determined, the residence time of juvenile bluefin tuna offshore Virginia was estimated to be at least 0.8 to 1.6years. A discriminant function analysis (DFA) plot of total PCB normalized signatures of PCB congeners showed three separate clusters, which suggested that bluefin tuna

  6. Discrimination of Juvenile Yellowfin (Thunnus albacares) and Bigeye (T. obesus) Tunas using Mitochondrial DNA Control Region and Liver Morphology

    PubMed Central

    Pedrosa-Gerasmio, Ivane R.; Babaran, Ricardo P.; Santos, Mudjekeewis D.

    2012-01-01

    Yellowfin tuna, Thunnus albacares (Bonnaterre, 1788) and bigeye tuna, Thunnus obesus (Lowe, 1839) are two of the most economically important tuna species in the world. However, identification of their juveniles, especially at sizes less than 40 cm, is very difficult, often leading to misidentification and miscalculation of their catch estimates. Here, we applied the mitochondrial DNA control region D-loop, a recently validated genetic marker used for identifying tuna species (Genus Thunnus), to discriminate juvenile tunas caught by purse seine and ringnet sets around fish aggregating devices (FADs) off the Southern Iloilo Peninsula in Central Philippines. We checked individual identifications using the Neighbor-Joining Method and compared results with morphometric analyses and the liver phenotype. We tested 48 specimens ranging from 13 to 31 cm fork length. Morpho-meristic analyses suggested that 12 specimens (25%) were bigeye tuna and 36 specimens (75%) were yellowfin tuna. In contrast, the genetic and liver analyses both showed that 5 specimens (10%) were bigeye tuna and 43 (90%) yellowfin tuna. This suggests that misidentification can occur even with highly stringent morpho-meristic characters and that the mtDNA control region and liver phenotype are excellent markers to discriminate juveniles of yellowfin and bigeye tunas. PMID:22536417

  7. Discrimination of juvenile yellowfin (Thunnus albacares) and bigeye (T. obesus) Tunas using mitochondrial DNA control region and liver morphology.

    PubMed

    Pedrosa-Gerasmio, Ivane R; Babaran, Ricardo P; Santos, Mudjekeewis D

    2012-01-01

    Yellowfin tuna, Thunnus albacares (Bonnaterre, 1788) and bigeye tuna, Thunnus obesus (Lowe, 1839) are two of the most economically important tuna species in the world. However, identification of their juveniles, especially at sizes less than 40 cm, is very difficult, often leading to misidentification and miscalculation of their catch estimates. Here, we applied the mitochondrial DNA control region D-loop, a recently validated genetic marker used for identifying tuna species (Genus Thunnus), to discriminate juvenile tunas caught by purse seine and ringnet sets around fish aggregating devices (FADs) off the Southern Iloilo Peninsula in Central Philippines. We checked individual identifications using the Neighbor-Joining Method and compared results with morphometric analyses and the liver phenotype. We tested 48 specimens ranging from 13 to 31 cm fork length. Morpho-meristic analyses suggested that 12 specimens (25%) were bigeye tuna and 36 specimens (75%) were yellowfin tuna. In contrast, the genetic and liver analyses both showed that 5 specimens (10%) were bigeye tuna and 43 (90%) yellowfin tuna. This suggests that misidentification can occur even with highly stringent morpho-meristic characters and that the mtDNA control region and liver phenotype are excellent markers to discriminate juveniles of yellowfin and bigeye tunas. PMID:22536417

  8. Effects of Stochasticity in Early Life History on Steepness and Population Growth Rate Estimates: An Illustration on Atlantic Bluefin Tuna

    PubMed Central

    Simon, Maximilien; Fromentin, Jean-Marc; Bonhommeau, Sylvain; Gaertner, Daniel; Brodziak, Jon; Etienne, Marie-Pierre

    2012-01-01

    The intrinsic population growth rate (r) of the surplus production function used in the biomass dynamic model and the steepness (h) of the stock-recruitment relationship used in age-structured population dynamics models are two key parameters in fish stock assessment. There is generally insufficient information in the data to estimate these parameters that thus have to be constrained. We developed methods to directly estimate the probability distributions of r and h for the Atlantic bluefin tuna (Thunnus thynnus, Scombridae), using all available biological and ecological information. We examined the existing literature to define appropriate probability distributions of key life history parameters associated with intrinsic growth rate and steepness, paying particular attention to the natural mortality for early life history stages. The estimated probability distribution of the population intrinsic growth rate was weakly informative, with an estimated mean r = 0.77 (±0.53) and an interquartile range of (0.34, 1.12). The estimated distribution of h was more informative, but also strongly asymmetric with an estimated mean h = 0.89 (±0.20) and a median of 0.99. We note that these two key demographic parameters strongly depend on the distribution of early life history mortality rate (M0), which is known to exhibit high year-to-year variations. This variability results in a widely spread distribution of M0 that affects the distribution of the intrinsic population growth rate and further makes the spawning stock biomass an inadequate proxy to predict recruitment levels. PMID:23119063

  9. Investigating relationships between albacore tuna ( Thunnus alalunga) CPUE and prey distribution in the Bay of Biscay

    NASA Astrophysics Data System (ADS)

    Lezama-Ochoa, Ainhoa; Boyra, Guillermo; Goñi, Nicolas; Arrizabalaga, Haritz; Bertrand, Arnaud

    2010-07-01

    The Bay of Biscay in the northeast Atlantic is an important feeding zone for juvenile albacore tuna ( Thunnus alalunga) during their summer migration northwards. Spatial distribution and abundance of their potential prey [planktonic organisms, anchovy ( Engraulis encrasicolus) and other small pelagics] were investigated in the southeast Bay of Biscay during acoustic surveys in autumn from 2003 to 2005. The relationships between albacore tuna catch per unit of effort (CPUE), and prey abundance and sea surface temperature (SST) were studied at different spatiotemporal scales. We observed positive and significant correlations between albacore tuna CPUE and anchovy abundance and total prey abundance, at different spatial scales. However, in 2003, a year characterised by extreme temperatures compared to the other years of this study, the relationship between CPUE and prey abundance was much weaker. Instead, we found a significant negative correlation with SST.

  10. Total mercury in canned yellowfin tuna Thunnus albacares marketed in northwest Mexico.

    PubMed

    Ruelas-Inzunza, Jorge; Patiño-Mejía, Carlos; Soto-Jiménez, Martín; Barba-Quintero, Guillermo; Spanopoulos-Hernández, Milton

    2011-12-01

    Mercury (Hg) was determined in Thunnus albacares canned in oil (from 7 to 10 samples per brand) and water (from 5 to 10 samples per brand) of five leading brands in Mexico in 2008. Potential health risk was estimated on the basis of Hg concentration and rate (1.43 kg year(-1)per capita) of tuna consumption in Mexico. Highest Hg concentrations were 0.51 ± 0.26 and 0.40 ± 0.24 μ gg(-1) dry weight in water and oil, respectively. Averaged Hg concentrations in tuna canned in water in the current study were comparable to values in Katsuwonus pelamis from Alabama; regarding the oil presentation, Hg levels were lower than in canned tuna collected in Mexico and comparable to values in canned tuna (species not identified) from Turkey. Hazard quotients were 0.0166 and 0.012 in water and oil, respectively. For the analyzed brands and considering tuna consumption in Mexican population, reference dose for this element was not exceeded; therefore, no human health risk is likely to occur. More work is necessary in relation to exposure to Hg from other sources, rates of consumption in strata of population with elevated fish consumption, size of canned tuna and on the role of Se against Hg toxicity. PMID:21911030

  11. Spatial scale, means and gradients of hydrographic variables define pelagic seascapes of bluefin and bullet tuna spawning distribution.

    PubMed

    Alvarez-Berastegui, Diego; Ciannelli, Lorenzo; Aparicio-Gonzalez, Alberto; Reglero, Patricia; Hidalgo, Manuel; López-Jurado, Jose Luis; Tintoré, Joaquín; Alemany, Francisco

    2014-01-01

    Seascape ecology is an emerging discipline focused on understanding how features of the marine habitat influence the spatial distribution of marine species. However, there is still a gap in the development of concepts and techniques for its application in the marine pelagic realm, where there are no clear boundaries delimitating habitats. Here we demonstrate that pelagic seascape metrics defined as a combination of hydrographic variables and their spatial gradients calculated at an appropriate spatial scale, improve our ability to model pelagic fish distribution. We apply the analysis to study the spawning locations of two tuna species: Atlantic bluefin and bullet tuna. These two species represent a gradient in life history strategies. Bluefin tuna has a large body size and is a long-distant migrant, while bullet tuna has a small body size and lives year-round in coastal waters within the Mediterranean Sea. The results show that the models performance incorporating the proposed seascape metrics increases significantly when compared with models that do not consider these metrics. This improvement is more important for Atlantic bluefin, whose spawning ecology is dependent on the local oceanographic scenario, than it is for bullet tuna, which is less influenced by the hydrographic conditions. Our study advances our understanding of how species perceive their habitat and confirms that the spatial scale at which the seascape metrics provide information is related to the spawning ecology and life history strategy of each species. PMID:25347411

  12. Spatial Scale, Means and Gradients of Hydrographic Variables Define Pelagic Seascapes of Bluefin and Bullet Tuna Spawning Distribution

    PubMed Central

    Alvarez-Berastegui, Diego; Ciannelli, Lorenzo; Aparicio-Gonzalez, Alberto; Reglero, Patricia; Hidalgo, Manuel; López-Jurado, Jose Luis; Tintoré, Joaquín; Alemany, Francisco

    2014-01-01

    Seascape ecology is an emerging discipline focused on understanding how features of the marine habitat influence the spatial distribution of marine species. However, there is still a gap in the development of concepts and techniques for its application in the marine pelagic realm, where there are no clear boundaries delimitating habitats. Here we demonstrate that pelagic seascape metrics defined as a combination of hydrographic variables and their spatial gradients calculated at an appropriate spatial scale, improve our ability to model pelagic fish distribution. We apply the analysis to study the spawning locations of two tuna species: Atlantic bluefin and bullet tuna. These two species represent a gradient in life history strategies. Bluefin tuna has a large body size and is a long-distant migrant, while bullet tuna has a small body size and lives year-round in coastal waters within the Mediterranean Sea. The results show that the models performance incorporating the proposed seascape metrics increases significantly when compared with models that do not consider these metrics. This improvement is more important for Atlantic bluefin, whose spawning ecology is dependent on the local oceanographic scenario, than it is for bullet tuna, which is less influenced by the hydrographic conditions. Our study advances our understanding of how species perceive their habitat and confirms that the spatial scale at which the seascape metrics provide information is related to the spawning ecology and life history strategy of each species. PMID:25347411

  13. Spatially explicit estimates of stocks sizes, structure and biomass of herring and blue whiting, and catch data of bluefin tuna

    NASA Astrophysics Data System (ADS)

    Huse, G.; MacKenzie, B. R.; Trenkel, V.; Doray, M.; Nøttestad, L.; Oskarsson, G.

    2014-07-01

    The north Atlantic is a productive marine region which has supported important commercial fisheries for centuries. Many of these fisheries have exploited the pelagic species, including herring, blue whiting and tuna. Here we present data on the distribution of herring and blue whiting based on surveys in the Norwegian Sea, the Bay of Biscay and Celtic Sea. We also present catch data on bluefin tuna, which has been depleted for decades, but historically used to be a key predator on the other pelagic stocks during summer. The results show that there have been substantial changes in the herring and blue whiting distribution during the 1990s and early 2000s. The earliest bluefin tuna catches noted were in 1907. The catches in the Norwegian Sea area peaked in the 1950s and there have been very small catches since the 1980s. The catches in the Mediterranean on the other hand peaked in the late 1990, and had subsequently a strong reduction.

  14. One-step triplex-polymerase chain reaction assay for the authentication of yellowfin (Thunnus albacares), bigeye (Thunnus obesus), and skipjack (Katsuwonus pelamis) tuna DNA from fresh, frozen, and canned tuna samples.

    PubMed

    Michelini, Elisa; Cevenini, Luca; Mezzanotte, Laura; Simoni, Patrizia; Baraldini, Mario; De Laude, Luca; Roda, Aldo

    2007-09-19

    A one-step triplex-polymerase chain reaction (PCR)-based assay was developed to discriminate between three tuna species, Thunnus albacares, Thunnus obesus, and Katsuwonus pelamis, even in highly processed food samples such as canned or cooked tuna. Diagnostic nucleotides were identified by direct sequencing and alignment of part of the mitochondrial cytochrome b gene of 30 authenticated exemplars, which allowed us to evaluate intraspecific variation and the genetic distance between three tuna species. The assay relies on a one-step triplex-PCR reaction in which in a single tube species-specific amplification products are generated only in the presence of the correct template nucleic acid and the species of origin of the DNA is indicated by the distinctive size of the PCR product. The identification of tuna species can be performed with a good accuracy, low cost, and with potential automation for large-scale high-throughput screenings in small in-house laboratories. PMID:17711337

  15. Bioaccumulation of mercury in muscle tissue of yellowfin tuna, Thunnus albacares, of the eastern Pacific Ocean.

    PubMed

    Ordiano-Flores, Alfredo; Galván-Magaña, Felipe; Rosiles-Martínez, Rene

    2011-12-01

    Tuna, like most large pelagic fish, are highly exploited by man, and it is, therefore, important to determine mercury (Hg) levels in these species in order to establish allowable limits for their consumption and/or contamination levels in the environment. In this study, we evaluated Hg accumulation in yellowfin tuna (Thunnus albacares) muscle in two different geographic sites of the eastern Pacific Ocean. There was a positive association between Hg content and tuna size in the equatorial zone (EQZ). Using adjusted sizes, the site of origin was a determinant factor in Hg accumulation. Sex, by contrast, did not affect Hg levels, suggesting that males and females have similar feeding habits. No Hg concentration was over the Hg content thresholds for large marine predators adopted by Mexican norms and by North American authorities (1 μg g(-1) w.w.). Hg input due to yellowfin tuna consumption represented from 9.84% to 35.87% in Baja California Sur and from 14.78% to 53.87% in EQZ of the provisional tolerable weekly intake adopted by the World Health Organization. The target hazard quotient for Hg was <1 in each group of the population studied, which indicates that consumption of yellowfin tuna is not a threat to human health. PMID:21739161

  16. Effects of temperature, epinephrine and Ca(2+) on the hearts of yellowfin tuna (Thunnus albacares).

    PubMed

    Blank, Jason M; Morrissette, Jeffery M; Davie, Peter S; Block, Barbara A

    2002-07-01

    Tuna are endothermic fish with high metabolic rates, cardiac outputs and aerobic capacities. While tuna warm their skeletal muscle, viscera, brain and eyes, their hearts remain near ambient temperature, raising the possibility that cardiac performance may limit their thermal niches. We used an in situ perfused heart preparation to investigate the effects of acute temperature change and the effects of epinephrine and extracellular Ca(2+) on cardiac function in yellowfin tuna (Thunnus albacares). Heart rate showed a strong temperature-dependence, ranging from 20 beats min(-1) at 10 degrees C to 109 beats min(-1) at 25 degrees C. Maximal stroke volume showed an inverse temperature-dependence, ranging from 1.4 ml kg(-1) at 15 degrees C to 0.9 ml kg(-1) at 25 degrees C. Maximal cardiac outputs were 27 ml kg(-1) min(-1) at 10 degrees C and 98 ml kg(-1) min(-1) at 25 degrees C. There were no significant effects of perfusate epinephrine concentrations between 1 and 100 nmol l(-1) at 20 degrees C. Increasing extracellular Ca(2+) concentration from 1.84 to 7.36 mmol l(-1) at 20 degrees C produced significant increases in maximal stroke volume, cardiac output and myocardial power output. These data demonstrate that changes in heart rate and stroke volume are involved in maintaining cardiac output during temperature changes in tuna and support the hypothesis that cardiac performance may limit the thermal niches of yellowfin tuna. PMID:12077164

  17. The effect of temperature on postprandial metabolism of yellowfin tuna (Thunnus albacares).

    PubMed

    Klinger, Dane H; Dale, Jonathan J; Gleiss, Adrian C; Brandt, Tyler; Estess, Ethan E; Gardner, Luke; Machado, Benjamin; Norton, Alex; Rodriguez, Luis; Stiltner, James; Farwell, Charles; Block, Barbara A

    2016-05-01

    Specific dynamic action (SDA), the increase in metabolic expenditure associated with consumption of a meal, represents a substantial portion of fish energy budgets and is highly influenced by ambient temperature. The effect of temperature on SDA has not been studied in yellowfin tuna (Thunnus albacares, Bonnaterre 1788), an active pelagic predator that occupies temperate and subtropical waters. The energetic cost and duration of SDA were calculated by comparing routine and post-prandial oxygen consumption rates. Mean routine metabolic rates in yellowfin tuna increased with temperature, from 136 mg O2 kg(-1)h(-1) at 20 °C to 211 mg O2 kg(-1)h at 24 °C. The mean duration of SDA decreased from 40.2h at 20 °C to 33.1h at 24 °C, while mean SDA coefficient, the percentage of energy in a meal that is consumed during digestion, increased from 5.9% at 20 °C to 12.7% at 24 °C. Digestion in yellowfin tuna is faster at a higher temperature but requires additional oxidative energy. Enhanced characterization of the role of temperature in SDA of yellowfin tuna deepens our understanding of tuna physiology and can help improve management of aquaculture and fisheries. PMID:26794613

  18. Rare occurrence of a bigeye tuna Thunnus obesus in British waters, with notes on other occurrences of sub-tropical tunas.

    PubMed

    Powell, A; Parry, G S; Houghton, J D R; Herdson, D M

    2009-09-01

    A freshly dead bigeye tuna Thunnus obesus was washed ashore near Burry Port, Wales (51 degrees 40' N; 4 degrees 15' W) in August, 2006. This is only the third occasion that the species has been observed in British waters, and is the largest and most northerly recorded specimen. PMID:20738588

  19. [Efficacy of the protein of canned tuna (Thunnus alalunga) in animal growth].

    PubMed

    Navarro, M P; Castrillón, A M; Ortega, R M; Varela, G

    1986-03-01

    The effect of the manufacturing process on canned tuna (Thunnus alalunga) by the sterilization procedure at 115 degrees C for 60 and 90 minutes on its protein quality was studied. Protein quality was mainly evaluated according to its efficiency for animal growth. Protein from food obtained by the sterilization procedure at 115 degrees C for 60 minutes was similar for animal growth to that from a standard casein-methionine diet. No changes in digestibility and biological values were found between both proteins. Nevertheless, when the sterilization procedure was prolonged up to 90 minutes, the protein suffered modifications. Thus, protein digestibility decreased in spite of the fact that protein digestibility remained unmodified. On the other hand, introduction of the mixed protein into a diet based on flour plus tuna sterilized at 115 degrees C for 90 minutes, was not capable of maintaining the optimum patterns for weight evolution. PMID:3632194

  20. 50 CFR 660.702 - Definitions.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... (Prionace glauca) Tunas: north Pacific albacore (Thunnus alalunga) yellowfin tuna (Thunnus albacares) bigeye tuna (Thunnus obesus) skipjack tuna (Katsuwonus pelamis) northern bluefin tuna (Thunnus orientalis...) Tunas: north Pacific albacore (Thunnus alalunga) yellowfin tuna (Thunnus albacares) bigeye tuna...

  1. The effect of stimulation frequency on the transmural ventricular monophasic action potential in yellowfin tuna Thunnus albacares.

    PubMed

    Patrick, S M; White, E; Brill, R W; Shiels, H A

    2011-02-01

    Monophasic action potentials (MAPs) were recorded from the spongy and compact layers of the yellowfin tuna Thunnus albacares ventricle as stimulation frequency was increased. MAP duration decreased with increase in stimulation frequency in both the spongy and compact myocardial layers, but no significant difference in MAP duration was observed between the layers. PMID:21284642

  2. Genetic diversity and historical demography of Atlantic bigeye tuna (Thunnus obesus).

    PubMed

    Martínez, Pilar; González, Elena G; Castilho, Rita; Zardoya, Rafael

    2006-05-01

    Bigeye (Thunnus obesus) is a large, pelagic, and migratory species of tuna that inhabits tropical and temperate marine waters worldwide. Previous studies based on mitochondrial RFLP data have shown that bigeye tunas from the Atlantic Ocean are the most interesting from a genetic point of view. Two highly divergent mitochondrial haplotype clades (I and II) coexist in the Atlantic Ocean. One is almost exclusive of the Atlantic Ocean whereas the other is also found in the Indo-Pacific Ocean. Bigeye tuna from the Atlantic Ocean is currently managed as a single stock, although this assumption remains untested at the genetic level. Therefore, genetic diversity was determined at the mitochondrial control region to test the null hypothesis of no population structure in bigeye tuna from the Atlantic Ocean. A total of 331 specimens were sampled from four locations in the Atlantic Ocean (Canada, Azores, Canary Islands, and Gulf of Guinea), and one in the Indian and Pacific Oceans, respectively. The reconstructed neighbor-joining phylogeny confirmed the presence of Clades I and II throughout the Atlantic Ocean. No apparent latitudinal gradient of the proportions of both clades in the different collection sites was observed. Hierarchical AMOVA tests and pairwise phi(ST) comparisons involving Atlantic Ocean Clades I and II were consistent with a single stock of bigeye tuna in the Atlantic Ocean. Population genetic analyses considering phylogroups independently supported gene flow within Clade II throughout the Atlantic Ocean, and within Clade I between Atlantic and Indo-Pacific Oceans. The latter result suggests present uni-directional gene flow from the Indo-Pacific into the Atlantic Ocean. Moreover, mismatch analyses dated divergence of Clades I and II during the Pleistocene, as previously proposed. In addition, migration rates were estimated using coalescent methods, and showed a net migration from Atlantic Ocean feeding grounds towards the Gulf of Guinea, the best

  3. 50 CFR 300.211 - Definitions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... name Scientific name Albacore Thunnus alalunga. Pacific bluefin tuna Thunnus orientalis. Southern bluefin tuna Thunnus maccoyii. Bigeye tuna Thunnus obesus. Skipjack tuna Katsuwonus pelamis. Yellowfin tuna Thunnus albacares. Little tuna Euthynnus affinis. Frigate mackerel Auxis thazard; Auxis...

  4. 50 CFR 300.211 - Definitions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... name Scientific name Albacore Thunnus alalunga. Pacific bluefin tuna Thunnus orientalis. Southern bluefin tuna Thunnus maccoyii. Bigeye tuna Thunnus obesus. Skipjack tuna Katsuwonus pelamis. Yellowfin tuna Thunnus albacares. Little tuna Euthynnus affinis. Frigate mackerel Auxis thazard; Auxis...

  5. Front variability and surface ocean features of the presumed southern bluefin tuna spawning grounds in the tropical southeast Indian Ocean

    NASA Astrophysics Data System (ADS)

    Nieblas, Anne-Elise; Demarcq, Hervé; Drushka, Kyla; Sloyan, Bernadette; Bonhommeau, Sylvain

    2014-09-01

    The southern bluefin tuna (SBT, Thunnus maccoyii) is an ecologically and economically valuable fish. However, surprisingly little is known about its critical early life history, a period when mortality is several orders of magnitude higher than at any other life stage, and when larvae are highly sensitive to environmental conditions. Ocean fronts can be important in creating favourable spawning conditions, as they are a convergence of water masses with different properties that can concentrate planktonic particles and lead to enhanced productivity. In this study, we examine the front activity within the only region where SBT have been observed to spawn: the tropical southeast Indian Ocean between Indonesia and Australia (10°S-20°S, 105°E-125°E). We investigate front activity and its relationship to ocean dynamics and surface features of the region. Results are also presented for the entire Indian Ocean (30°N-45°S, 20°E-140°E) to provide a background context. We use an extension of the Cayula and Cornillon algorithm to detect ocean fronts from satellite images of sea surface temperature (SST) and chlorophyll-a concentration (chl-a). Front occurrence represents the probability of occurrence of a front at each pixel of an image. Front intensity represents the magnitude of the difference between the two water masses that make up a front. Relative to the rest of the Indian Ocean, both SST and chl-a fronts in the offshore spawning region are persistent in occurrence and weak in intensity. Front occurrence and intensity along the Australian coast are high, with persistent and intense fronts found along the northwest and west coasts. Fronts in the tropical southeast Indian Ocean are shown to have strong annual variability and some moderate interannual variability. SST front occurrence is found to lead the Southern Oscillation Index by one year, potentially linked to warming and wind anomalies in the Indian Ocean. The surface ocean characteristics of the offshore

  6. Spatiotemporal variability in bigeye tuna ( Thunnus obesus) dive behavior in the central North Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Howell, Evan A.; Hawn, Donald R.; Polovina, Jeffrey J.

    2010-07-01

    Data from 29 pop-up archival transmission (PAT) tags deployed on commercial-size bigeye tuna ( Thunnus obesus) in the central North Pacific Ocean from 4°N to 32°N were analyzed to describe variability in their dive behavior across space and time. During the day, bigeye tuna generally spent time in the 0-50 m and 300-400 m depth ranges, with spatial and temporal variability in the deep mode. At night, bigeye tuna generally inhabited the 0-100 m depth range. Three daily dive types were defined based on the percentage of time tuna spent in specific depth layers during the day. These three types were defined as shallow, intermediate, and deep and represented 24.4%, 18.8%, and 56.8% of the total number of days in the study, respectively. More shallow and intermediate dive-type behavior was found in the first half of the year, and in latitudes from 14°N to 16°N and north of 28°N. A greater amount of deep-dive behavior was found in the regions south of 10°N and between 18°N and 28°N during the third and fourth quarters of the year. Dive-type behavior also varied with oceanographic conditions, with more shallow and intermediate behavior found in colder surface waters. Intermediate and deep-dive types were pooled to reflect the depths where bigeye tuna may have potential interactions with fishing gear. A Generalized Additive Model was used to quantify the effects of time, space, and sea surface temperature on this pooled dive type. Results from the model showed that while latitude and quarter of the year were important parameters, sea surface temperature had the most significant effect on the pooled intermediate and deep-dive behavior. Model predictions indicated that the largest percentage of potential interaction would occur in the fourth quarter in the region from 18°N-20°N, which corresponds to the time and place of the highest bigeye tuna catch rates by the Hawaii-based long-line fishery. These results suggest that a model framework using these three

  7. Form and function of the bulbus arteriosus in yellowfin tuna (Thunnus albacares), bigeye tuna (Thunnus obesus) and blue marlin (Makaira nigricans): static properties.

    PubMed

    Braun, Marvin H; Brill, Richard W; Gosline, John M; Jones, David R

    2003-10-01

    The juxtaposition of heart and gills in teleost fish means that the Windkessel function characteristic of the whole mammalian arterial tree has to be subserved by the extremely short ventral aorta and bulbus arteriosus. Over the functional pressure range, arteries from blue marlin (Makaira nigricans) and yellowfin tuna (Thunnus albacares) have J-shaped pressure-volume (P-V) loops, while bulbi from the same species have r-shaped P-V loops, with a steep initial rise followed by a compliant plateau phase. The steep initial rise in pressure is due to the geometry of the lumen. The interactions between radius, pressure and tension require a large initial pressure to open the bulbar lumen for flow. The plateau is due to the unique organization of the bulbar wall. The large elastin:collagen ratio, limited amount of collagen arranged circumferentially, lack of elastin lamellae and low hydrophobicity of the elastin itself all combine to lower stiffness, increase extensibility and allow efficient recoil. Even though the modulus of bulbus material is much lower than that of an artery, at large volumes the overall stiffness of the bulbus increases rapidly. The morphological features that give rise to the special inflation characteristics of the bulbus help to extend flow and maintain pressure during diastole. PMID:12939364

  8. Transectional heat transfer in thermoregulating bigeye tuna (Thunnus obesus) - a 2D heat flux model.

    PubMed

    Boye, Jess; Musyl, Michael; Brill, Richard; Malte, Hans

    2009-11-01

    We developed a 2D heat flux model to elucidate routes and rates of heat transfer within bigeye tuna Thunnus obesus Lowe 1839 in both steady-state and time-dependent settings. In modeling the former situation, we adjusted the efficiencies of heat conservation in the red and the white muscle so as to make the output of the model agree as closely as possible with observed cross-sectional isotherms. In modeling the latter situation, we applied the heat exchanger efficiencies from the steady-state model to predict the distribution of temperature and heat fluxes in bigeye tuna during their extensive daily vertical excursions. The simulations yielded a close match to the data recorded in free-swimming fish and strongly point to the importance of the heat-producing and heat-conserving properties of the white muscle. The best correspondence between model output and observed data was obtained when the countercurrent heat exchangers in the blood flow pathways to the red and white muscle retained 99% and 96% (respectively) of the heat produced in these tissues. Our model confirms that the ability of bigeye tuna to maintain elevated muscle temperatures during their extensive daily vertical movements depends on their ability to rapidly modulate heating and cooling rates. This study shows that the differential cooling and heating rates could be fully accounted for by a mechanism where blood flow to the swimming muscles is either exclusively through the heat exchangers or completely shunted around them, depending on the ambient temperature relative to the body temperature. Our results therefore strongly suggest that such a mechanism is involved in the extensive physiological thermoregulatory abilities of endothermic bigeye tuna. PMID:19880733

  9. The sequence and organization of complete mitochondrial genome of the yellowfin tuna, Thunnus albacares (Bonnaterre, 1788).

    PubMed

    Pang, Jiaohui; Cheng, Qiqun; Sun, Dandan; Zhang, Heng; Jin, Shaofei

    2016-09-01

    Yellowfin tuna (Thunnus albacares) is one of the most important economic fishes around the world. In the present study, we determined the complete mitochondrial DNA sequence and organization of T. albacares. The entire mitochondrial genome is a circular-molecule of 16,528 bp in length, which encodes 37 genes in all. These genes comprise 13 protein-coding genes (ATP6 and 8, COI-III, Cytb, ND1-6 and 4 L), 22 transfer RNA genes (tRNAs), and 2 ribosomal RNA genes (12S and 16S rRNAs). The complete mitochondrial genome sequence of T. albacares can provide basic information for the studies on molecular taxonomy and conservation genetics of teleost fishes. PMID:25707413

  10. Preparation and structural analysis of actinidain-processed atelocollagen of yellowfin tuna (Thunnus albacares).

    PubMed

    Morimoto, Koichi; Kunii, Saori; Hamano, Kaori; Tonomura, Ben'ichiro

    2004-04-01

    Pepsin-hydrolyzed collagen (atelocollagen) is a trimer, consisting of alpha 1 and alpha 2 monomers, and shows molecular species corresponding to a monomer, dimer (beta chain), and trimer (gamma chain) by SDS-polyacrylamide gel electrophoresis. Atelocollagen was purified from yellowfin tuna (Thunnus albacares) by salt precipitation and cation-exchange chromatography. Enzymatic hydrolysis of the atelocollagen by actinidain, a cysteine protease purified from kiwifruit, was analyzed by SDS-polyacrylamide gel electrophoresis. The triple helical structure unique to collagen was retained in the atelocollagen as judged by circular dichroism spectra. The actinidain-processed atelocollagen showed only monomeric alpha 1 and alpha 2 chains, with no beta and gamma chains, by SDS-polyacrylamide gel electrophoresis; nevertheless, it retained the typical triple helical structure. It is suggested that actinidain cleaved the atelocollagen molecule at specific sites on the inside of the inter-strand cross-linking peptides. PMID:15118315

  11. Kudoa thunni from blackfin tuna (Thunnus atlanticus) harvested off the island of St. Kitts, West Indies.

    PubMed

    Griffin, Matt; Quiniou, Sylvie; Ware, Cynthia; Bogdanovic, Lewis; Soto, Esteban

    2014-02-01

    Numerous myxozoan cysts (∼ 1 mm) were found in the musculature of blackfin tuna (Thunnus atlanticus) harvested off the Caribbean island of St. Kitts. Myxospores were consistent with quadrate members of the Kudoidae, measuring 8.8 (8.2-9.4) μm wide, 7.3 (6.6-8.3) μm thick, and 6.2 (5.8-6.9) μm long with 4 uniform drop-like polar capsules measuring 2.7 (2.2-3.2) μm long and 2.0 (1.7-2.2) μm wide. The 18S small-subunit (SSU) and 28S large-subunit (LSU) ribosomal DNA sequences did not result in direct matches to any published sequences. However, the SSU sequences (1,786 base pairs [bp]) obtained from 6 individual cysts were identical and demonstrated high homology to Kudoa thunni (99.0%) from albacore (Thunnus alalunga). Alternatively, 33 unique sequences were obtained for the LSU (∼ 800 bp), demonstrating 0.1 to 5.0% variability between them, although a majority of these sequences (60%) demonstrated high homology (>99%) to K. thunni. Morphologically, the case isolate was smaller than published descriptions of K. thunni; however, rDNA sequence homology, and phylogenetic placement based on concatenated SSU and LSU rDNA sequences suggests this case isolate and K. thunni are conspecific. To our knowledge this is the first report of K. thunni infection in blackfin tuna from the Caribbean. PMID:23984875

  12. Distinct Yellowfin Tuna (Thunnus albacares) Stocks Detected in Western and Central Pacific Ocean (WCPO) Using DNA Microsatellites.

    PubMed

    Aguila, Roselyn D; Perez, Sweedy Kay L; Catacutan, Billy Joel N; Lopez, Grace V; Barut, Noel C; Santos, Mudjekeewis D

    2015-01-01

    The yellowfin tuna, Thunnus albacares (Bonnaterre, 1788), covers majority of the Philippines' tuna catch, one of the major fisheries commodities in the country. Due to its high economic importance sustainable management of these tunas has become an imperative measure to prevent stock depletion. Currently, the Philippine yellowfin tuna is believed to be part of a single stock of the greater WCPO though some reports suggest otherwise. This study therefore aims to establish the genetic stock structure of the said species in the Philippines as compared to Bismarck Sea, Papua New Guinea using nine (9) DNA microsatellite markers. DNA microsatellite data revealed significant genetic differentiation between the Philippine and Bismarck Sea, Papua New Guinea yellowfin tuna samples. (FST = 0.034, P = 0.016), which is further supported by multilocus distance matrix testing (PCoA) and model-based clustering (STRUCTURE 2.2).With these findings, this study posits that the yellowfin tuna population in the Philippines is a separate stock from the Bismarck Sea population. These findings add evidence to the alternative hypothesis of having at least 2 subpopulations of yellowfin tuna in the WCPO and calls for additional scientific studies using other parameters to investigate this. Accurate population information is necessary in formulating a more appropriate management strategy for the sustainability of the yellowfin tuna not only in the Philippines but also in the WCPO. PMID:26394234

  13. Distinct Yellowfin Tuna (Thunnus albacares) Stocks Detected in Western and Central Pacific Ocean (WCPO) Using DNA Microsatellites

    PubMed Central

    Aguila, Roselyn D.; Perez, Sweedy Kay L.; Catacutan, Billy Joel N.; Lopez, Grace V.; Barut, Noel C.; Santos, Mudjekeewis D.

    2015-01-01

    The yellowfin tuna, Thunnus albacares (Bonnaterre, 1788), covers majority of the Philippines’ tuna catch, one of the major fisheries commodities in the country. Due to its high economic importance sustainable management of these tunas has become an imperative measure to prevent stock depletion. Currently, the Philippine yellowfin tuna is believed to be part of a single stock of the greater WCPO though some reports suggest otherwise. This study therefore aims to establish the genetic stock structure of the said species in the Philippines as compared to Bismarck Sea, Papua New Guinea using nine (9) DNA microsatellite markers. DNA microsatellite data revealed significant genetic differentiation between the Philippine and Bismarck Sea, Papua New Guinea yellowfin tuna samples. (FST = 0.034, P = 0.016), which is further supported by multilocus distance matrix testing (PCoA) and model-based clustering (STRUCTURE 2.2).With these findings, this study posits that the yellowfin tuna population in the Philippines is a separate stock from the Bismarck Sea population. These findings add evidence to the alternative hypothesis of having at least 2 subpopulations of yellowfin tuna in the WCPO and calls for additional scientific studies using other parameters to investigate this. Accurate population information is necessary in formulating a more appropriate management strategy for the sustainability of the yellowfin tuna not only in the Philippines but also in the WCPO. PMID:26394234

  14. Evaluation of Atlantic bluefin tuna reproductive potential in the western Mediterranean Sea

    NASA Astrophysics Data System (ADS)

    Aranda, Guillermo; Medina, Antonio; Santos, Agustín; Abascal, Francisco J.; Galaz, Txema

    2013-02-01

    Ovarian tissue samples of Atlantic bluefin tuna (ABFT) spawners (n = 49) caught by purse seine in the Balearic Sea (western Mediterranean) were used to assess the stock reproductive characteristics. The frequency of spawning females estimated by the postovulatory follicle method was 84% and the spawning periodicity 1.2 days. Using an unbiased stereological method, the realized batch fecundity was estimated from counts of postovulatory follicles (POFs), whereas the batch fecundity of the subsequent spawn was estimated by quantification of the number of follicles containing oocytes at maturation stage (OMFs). The number of POFs was used as a reliable proxy of the realized batch fecundity, as it represents the actual number of eggs released in the last spawning event. The average relative realized batch fecundity was estimated to be approximately 48 eggs g- 1 of total body mass. While the absolute batch fecundity was isometrically related to the fork length, the relative batch fecundity was not dependent on fish size, which leads to the assumption that all length classes contribute proportionally to their size, towards the total number of eggs spawned by the broodstock. Size-related variations in the sex ratio were observed in the study area and in other Mediterranean locations; females were more abundant in mid-size classes while males predominated in large-size classes.

  15. Euryphorus brachypterus (Copepoda: Caligidae) on wild pacific bluefin tuna from the Tsugaru Strait, northern Japan.

    PubMed

    Kanaiwa, Minoru; Yamamoto, Yuki; Hiraoka, Yuko; Kato, Minoru; Ishimura, Gakushi; Katahira, Hirotaka

    2016-06-01

    Parasitic copepods infecting large scombrid fishes have been known for a long time because their hosts are economically important. Most studies, however, have focused on their morphology or their infection status in aquaculture from pathological viewpoints, and very few quantitative surveys have been conducted under conditions in the wild. This study therefore investigated the prevalence of Euryphorus brachypterus (Caligidae) in wild Pacific bluefin tuna (PBF). Results of sampling from August to September 2014 at the western area of the Tsugaru Strait, Japan showed that 13.2% of the PBF individuals (n=1978) were infected with this copepod. The prevalence of infections was highest in larger fish but varied among landing dates, which were classified into three clusters and in all smaller fish, the prevalence of infections was zero. This suggests that E. brachypterus mainly uses the larger PBF, which becomes sources of further infections in other seas, and that at least two host populations with different infection statuses at the strait. PMID:26861209

  16. Enzymatic hydrolysis of starry triggerfish (Abalistes stellaris) muscle using liver proteinase from albacore tuna (Thunnus alalunga).

    PubMed

    Sripokar, P; Chaijan, M; Benjakul, S; Kishimura, H; Klomklao, S

    2016-02-01

    Proteinases from liver extract from albacore tuna (Thunnus alalunga) were used to produce protein hydrolysate from starry triggerfish (Abalistes stellaris) muscle. Hydrolysis conditions for preparing protein hydrolysate from starry triggerfish muscle were optimized. Enzyme level, reaction time and fish muscle/buffer ratio significantly affected the hydrolysis (p < 0.05). Optimum conditions for triggerfish muscle hydrolysis were 5.5 % liver extract, 40 min reaction time and fish muscle/buffer ratio of 1:3 (w/v). The freeze-dried protein hydrolysate was characterized with respect to chemical composition, amino acid composition and color. The product contained 91.73 % protein, 2.04 % lipid and 6.48 % ash. The protein hydrolysate exhibited high amount of essential amino acids (45.62 %). It was light yellow in color (L (*) = 82.94, a (*) = 0.84, b (*) = 22.83). The results indicate that the extract from liver of albacore tuna could be used to produce fish protein hydrolysate and protein hydrolysate from starry triggerfish muscle may potentially serve as a good source of desirable peptide and amino acids. PMID:27162384

  17. Growth and mortality rates of bigeye tuna Thunnus obesus (Perciformes: Scombridae) in the central Atlantic Ocean.

    PubMed

    Zhu, Guoping; Xu, Liuxiong; Zhou, Yingqi; Chen, Xinjun

    2009-01-01

    Age and growth parameters were estimated for bigeye tuna Thunnus obesus Lowe, 1839 sampled from China longline fisheries in the central Atlantic Ocean from October 2002 to July 2003 and from August 2004 to March 2005. The von Bertalanffy growth parameters were estimated at L(infinity)=217.9 cm fork length, k=0.23 year(-1), and t(0)=-0.44 year. The total mortality rate (Z) was estimated to be from 0.82 to 1.02, the fishing mortality (F) and the natural mortality were 0.54 year(-1) and 0.39 year(-1), respectively. The exploitation ratio (E) was 0.35. This study provides the detailed estimates of growth and mortality rate for bigeye tuna in the central Atlantic Ocean, which can be used as biological input parameters in further stock evaluations in this region. However, age analysis, additional validation of the size composition and stock structure are needed for future studies. PMID:19637690

  18. Characteristics of collagens from the swim bladders of yellowfin tuna (Thunnus albacares).

    PubMed

    Kaewdang, Onouma; Benjakul, Soottawat; Kaewmanee, Thammarat; Kishimura, Hideki

    2014-07-15

    Acid soluble collagen (ASC) and pepsin soluble collagen (PSC) were extracted from the swim bladders of yellowfin tuna (Thunnus albacares) with yields of 1.07% and 12.10%, respectively. Based on electrophoretic patterns, both ASC and PSC consisted of two α-chains (α1 and α2) and were characterised to be type I collagen. ASC had higher β-chains than PSC. Imino acid contents of ASC and PSC were 128 and 169 residues/1,000 residues, respectively. Fourier transform infrared (FTIR) spectra of both ASC and PSC were similar and revealed the presence of a triple helix. Both ASC and PSC had the highest solubility at acidic pHs. From zeta potential analysis, a net charge of zero was found at pH 6.05 and 5.93 for ASC and PSC, respectively. Tmax of ASC and PSC were 32.97 and 33.92°C, respectively. The swim bladders of yellowfin tuna could therefore serve as an alternative source of collagen for future applications. PMID:24594184

  19. Pericardial and vascular pressures and blood flow in the albacore tuna, Thunnus alalunga.

    PubMed

    Lai, N C; Graham, J B; Lowell, W R; Laurs, R M

    1987-01-01

    Pericardial, ventricular, and dorsal aortic pressures, and blood flow were measured in tabled, anesthetized albacore tuna, Thunnus alalunga (7.8-10.7 kg) captured at sea off Monterey, California (USA) during August 1985. Mean pericardial pressure was -10.0/-2.6 cm H2O (Systolic/Diastolic, [S/D]) and mean pericardial pulse pressure was 7.5. Heart rate averaged 87 beats per minute. Mean ventricular pressure was 97.0/12.9 cm H2O [S/D] and mean dorsal aortic pressure was 64. High ventricular and dorsal aortic pressures of albacore reflect the perfusion requirement of its metabolically active tissues and compensate for the energy losses resulting from blood flow through the gills to arterial heat exchanger to capillaries and again back to the venous heat exchanger. As in elasmobranchs, the remarkably high pericardial pulse pressure, large pericardial volume, and negative pericardial pressure in the albacore suggest that its pericardium is more rigid than that of most teleosts and thus facilitates cardiac filling. Published cardiac output values for most non-tunas, when corrected for body size differences, are less than the mean weight specific cardiac output of albacore (29.4 ml/kg per min, range 12.9-51.9). PMID:3582589

  20. Spatially explicit estimates of stock sizes, structure and biomass of herring and blue whiting, and catch data of bluefin tuna

    NASA Astrophysics Data System (ADS)

    Huse, G.; MacKenzie, B. R.; Trenkel, V.; Doray, M.; Nøttestad, L.; Oskarsson, G.

    2015-04-01

    The North Atlantic is a productive marine region which has supported important commercial fisheries for centuries. Many of these fisheries have exploited the pelagic species, including herring, blue whiting and tuna. Here we present data on the distribution of herring and blue whiting based on the international ecosystem survey in the Nordic Seas (IESNS), the bottom trawl survey in the Bay of Biscay and Celtic Sea (EVHOE) and the pelagic survey in the Bay of Biscay (PELGAS). We also present catch data on bluefin tuna, which has been depleted for decades but historically used to be a key predator on the other pelagic stocks during summer. The results show that there were substantial changes in the herring and blue whiting distribution during the 1990s and early 2000s. The earliest bluefin tuna catches noted were in 1907. The catches in the Norwegian Sea area peaked in the 1950s and there have been very small catches since the 1980s. The reported catches in the Mediterranean, on the other hand, peaked in the late 1990s and subsequently had a strong reduction.

  1. Identification of tuna species in commercial cans by minor groove binder probe real-time polymerase chain reaction analysis of mitochondrial DNA sequences.

    PubMed

    Terio, Valentina; Di Pinto, Pietro; Decaro, Nicola; Parisi, Antonio; Desario, Costantina; Martella, Vito; Buonavoglia, Canio; Tantillo, Marilia Giuseppina

    2010-12-01

    Three different minor groove binder (MGB) probe assays have been developed for rapid and accurate identification of the species commonly used for production of canned tuna, i.e. yellowfin (Thunnus albacares), bluefin (Thunnus thynnus) and albacore (Thunnus alalunga) tunas. The assays targeting the mitochondrial cytochrome b gene were able to discriminate efficiently between the three species contained in fresh or canned tunas and did not react with other Scombroidei that were tested. A correct species prediction was obtained even from artificial mixtures prepared with different amounts of the reference tuna species and subjected to the sterilisation treatment. Testing of 27 commercial canned tunas by PCR-RFLP, MGB probe assays and sequence analysis showed a concordance of 100% between the last two techniques, whereas by using PCR-RFLP several samples were uncharacterised or mischaracterised. These results make the established MGB probe assays an attractive tool for direct and rapid species identification in canned tuna. PMID:20691254

  2. Thunniform swimming: muscle dynamics and mechanical power production of aerobic fibres in yellowfin tuna (Thunnus albacares).

    PubMed

    Shadwick, Robert E; Syme, Douglas A

    2008-05-01

    We studied the mechanical properties of deep red aerobic muscle of yellowfin tuna (Thunnus albacares), using both in vivo and in vitro methods. In fish swimming in a water tunnel at 1-3 L s(-1) (where L is fork length), muscle length changes were recorded by sonomicrometry, and activation timing was quantified by electromyography. In some fish a tendon buckle was also implanted on the caudal tendon to measure instantaneous muscle forces transmitted to the tail. Between measurement sites at 0.45 to 0.65 L, the wave of muscle shortening progressed along the body at a relatively high velocity of 1.7 L per tail beat period, and a significant phase shift (31+/-4 degrees ) occurred between muscle shortening and local midline curvature, both suggesting red muscle power is directed posteriorly, rather than causing local body bending, which is a hallmark of thunniform swimming. Muscle activation at 0.53 L was initiated at about 50 degrees of the tail beat period and ceased at about 160 degrees , where 90 degrees is peak muscle length and 180 degrees is minimum length. Strain amplitude in the deep red fibres at 0.5 L was +/-5.4%, double that predicted from midline curvature analysis. Work and power production were measured in isolated bundles of red fibres from 0.5 L by the work loop technique. Power was maximal at 3-4 Hz and fell to less than 50% of maximum after 6 Hz. Based on the timing of activation, muscle strain, tail beat frequencies and forces in the caudal tendon while swimming, we conclude that yellowfin tuna, like skipjack, use their red muscles under conditions that produce near-maximal power output while swimming. Interestingly, the red muscles of yellowfin tuna are slower than those of skipjack, which corresponds with the slower tail beat frequencies and cruising speeds in yellowfin. PMID:18456888

  3. Next-generation sequencing of the yellowfin tuna mitochondrial genome reveals novel phylogenetic relationships within the genus Thunnus.

    PubMed

    Guo, Liang; Li, Mingming; Zhang, Heng; Yang, Sen; Chen, Xinghan; Meng, Zining; Lin, Haoran

    2016-05-01

    Recently, the next-generation sequencing (NGS) technology has become a powerful tool for sequencing the teleost mitochondrial genome (mitogenome). Here, we used this technology to determine the mitogenome of the yellowfin tuna (Thunnus albacares). A total of 41,378 reads were generated by Illumina platform with an average depth of 250×. The mitogenome (16,528 bp in length) contained 37 mitochondrial genes with the similar gene order to other typical teleosts. These mitochondrial genes were encoded on the heavy strand except for ND6 and eight tRNA genes. The result of phylogenetic analysis supported two distinct clades dividing the genus Thunnus, but the tuna species of these two genetic clades were different from that of two recognized subgenus based on anatomical characters and geographical distribution. Our results might help to understand the structure, function, and evolutionary history of the yellowfin tuna mitogenome and also provide valuable new insights for phylogenetic affinity of tuna species. PMID:25418629

  4. The potential impact of ocean acidification upon eggs and larvae of yellowfin tuna (Thunnus albacares)

    NASA Astrophysics Data System (ADS)

    Bromhead, Don; Scholey, Vernon; Nicol, Simon; Margulies, Daniel; Wexler, Jeanne; Stein, Maria; Hoyle, Simon; Lennert-Cody, Cleridy; Williamson, Jane; Havenhand, Jonathan; Ilyina, Tatiana; Lehodey, Patrick

    2015-03-01

    Anthropogenic carbon dioxide (CO2) emissions are resulting in increasing absorption of CO2 by the earth's oceans, which has led to a decline in ocean pH, a process known as ocean acidification (OA). Evidence suggests that OA may have the potential to affect the distribution and population dynamics of many marine organisms. Early life history processes (e.g. fertilization) and stages (eggs, larvae, juveniles) may be relatively more vulnerable to potential OA impacts, with implications for recruitment in marine populations. The potential impact of OA upon tuna populations has not been investigated, although tuna are key components of pelagic ecosystems and, in the Pacific Ocean, form the basis of one of the largest and most valuable fisheries in the world. This paper reviews current knowledge of potential OA impacts on fish and presents results from a pilot study investigating how OA may affect eggs and larvae of yellowfin tuna, Thunnus albacares. Two separate trials were conducted to test the impact of pCO2 on yellowfin egg stage duration, larval growth and survival. The pCO2 levels tested ranged from present day (~400 μatm) to levels predicted to occur in some areas of the spawning habitat within the next 100 years (<2500 μatm) to 300 years (~<5000 μatm) to much more extreme levels (~10,000 μatm). In trial 1, there was evidence for significantly reduced larval survival (at mean pCO2 levels≥4730 μatm) and growth (at mean pCO2 levels≥2108 μatm), while egg hatch time was increased at extreme pCO2 levels≥10,000 μatm (*intermediate levels were not tested). In trial 2, egg hatch times were increased at mean pCO2 levels≥1573 μatm, but growth was only impacted at higher pCO2 (≥8800 μatm) and there was no relationship with survival. Unstable ambient conditions during trial 2 are likely to have contributed to the difference in results between trials. Despite the technical challenges with these experiments, there is a need for future empirical work which

  5. Direct evidence for Mendelian inheritance of the variations in the ribosomal protein gene introns in yellowfin tuna (Thunnus albacares).

    PubMed

    Chow, S; Scholey, V P; Nakazawa, A; Margulies, D; Wexler, J B; Olson, R J; Hazama, K

    2001-01-01

    Restriction fragment length polymorphism found in the S7 ribosomal protein gene introns of yellowfin tuna (Thunnus albacares) was compared between a single pair of parents and their offspring. The sizes of the first intron ( RP1) and second intron ( RP2) amplified by polymerase chain reaction were 810 bp and 1400 bp, respectively. The dam and sire had different restriction types from one another in HhaI and RsaI digestions for RP1 and in DdeI, HhaI, and ScrFI digestions for RP2. Putative genotypes in both introns of 64 larvae were found to be segregated in Mendelian proportions. Genotype distributions in a wild yellowfin tuna sample ( n = 34) were in Hardy-Weinberg proportions, and observed heterozygosity ranged from 0.149 to 0.388. This study presents novel Mendelian markers, which are feasible for tuna population genetic study and pedigree analysis. PMID:14961386

  6. Comparative study of muscle proteins in relation to the development of yake in three tropical tuna species yellowfin (Thunnus albacares), big eye (Thunnus obesus) and skipjack (Katsuwonus pelamis).

    PubMed

    Erdaide, Oihane; Lekube, Xabier; Olsen, Ragnar L; Ganzedo, Unai; Martinez, Iciar

    2016-06-15

    Burnt tuna (BT), or yake-niku, is a quality flaw of the muscle characterised by a pale colour and grainy and exudative texture. Cathepsin-L, water soluble and total protein components from normal and BT muscles, from three tropical tuna species - yellowfin (YFT, Thunnus albacares), bigeye (BET, Thunnus obesus) and skipjack (SKJ, Katsuwonus pelamis) - were compared by electrophoretic and western blot analyses to identify biomarkers for BT. As expected, SDS-PAGE patterns were species-specific but differences, due to BT, were observed only between some low ionic strength extracts of BET and YFT. Protein oxidation and cell proliferation analysed by immunoblotting did not show differences between BT and normal muscles. Gelatine zymography revealed different gelatinase activity patterns that, although not linked to BT, may affect the final texture of the muscle. A 43 kDa band, identified as creatine kinase by proteomic analysis, showed the potential to be a good indicator for BT in BET and YFT. PMID:26868578

  7. Evaluation of three harvest control rules for Bigeye Tuna ( Thunnus obesus) fisheries in the Indian Ocean

    NASA Astrophysics Data System (ADS)

    Tong, Yuhe; Chen, Xinjun; Kolody, Dale

    2014-10-01

    The stock of Bigeye tuna ( Thunnus obesus) in the Indian Ocean supports an important international fishery and is considered to be fully exploited. The responsible management agency, the Indian Ocean Tuna Commission (IOTC), does not have an explicit management decision-making framework in place to prevent over-fishing. In this study, we evaluated three harvest control rules, i) constant fishing mortality (CF), from 0.2 to 0.6, ii) constant catch (CC), from 60000 to 140000 t, and iii) constant escapement (CE), from 0.3 to 0.7. The population dynamics simulated by the operating model was based on the most recent stock assessment using Stock Synthesis version III (SS3). Three simulation scenarios (low, medium and high productivity) were designed to cover possible uncertainty in the stock assessment and biological parameters. Performances of three harvest control rules were compared on the basis of three management objectives (over 3, 10 and 25 years): i) the probability of maintaining spawning stock biomass above a level that can sustain maximum sustainable yield (MSY) on average, ii) the probability of achieving average catches between 0.8 MSY and 1.0 MSY, and iii) inter-annual variability in catches. The constant escapement strategy ( CE=0.5), constant fishing mortality strategy ( F=0.4) and constant catch ( CC=80000) were the most rational among the respective management scenarios. It is concluded that the short-term annual catch is suggested at 80000 t, and the potential total allowable catch for a stable yield could be set at 120000 t once the stock had recovered successfully. All the strategies considered in this study to achieve a `tolerable' balance between resource conservation and utilization have been based around the management objectives of the IOTC.

  8. Analyses of nuclear ldhA gene and mtDNA control region sequences of Atlantic northern bluefin tuna populations.

    PubMed

    Ely, B; Stoner, D S; Bremer, Alvarado J R; Dean, J M; Addis, P; Cau, A; Thelen, E J; Jones, W J; Black, D E; Smith, L; Scott, K; Naseri, I; Quattro, J M

    2002-12-01

    There has been considerable debate about whether the Atlantic northern bluefin tuna exist as a single panmictic unit. We have addressed this issue by examining both mitochondrial DNA control region nucleotide sequences and nuclear gene ldhA allele frequencies in replicate size or year class samples of northern bluefin tuna from the Mediterranean Sea and the northwestern Atlantic Ocean. Pairwise comparisons of multiple year class samples from the 2 regions provided no evidence for population subdivision. Similarly, analyses of molecular variance of both mitochondrial and ldhA data revealed no significant differences among or between samples from the 2 regions. These results demonstrate the importance of analyzing multiple year classes and large sample sizes to obtain accurate estimates when using allele frequencies to characterize a population. It is important to note that the absence of genetic evidence for population substructure does not unilaterally constitute evidence of a single panmictic population, as genetic differentiation can be prevented by large population sizes and by migration. PMID:14961233

  9. Responses of the red blood cells from two high-energy-demand teleosts, yellowfin tuna (Thunnus albacares) and skipjack tuna (Katsuwonus pelamis), to catecholamines.

    PubMed

    Lowe, T E; Brill, R W; Cousins, K L

    1998-08-01

    In fishes, catecholamines increase red blood cell intracellular pH through stimulation of a sodium/proton (Na+/H+) antiporter. This response can counteract potential reductions in blood O2 carrying capacity (due to Bohr and Root effects) when plasma pH and intracellular pH decrease during hypoxia, hypercapnia, or following exhaustive exercise. Tuna physiology and behavior dictate exceptionally high rates of O2 delivery to the tissues often under adverse conditions, but especially during recovery from exhaustive exercise when plasma pH may be reduced by as much as 0.4 pH units. We hypothesize that blood O2 transport during periods of metabolic acidosis could be especially critical in tunas and the response of rbc to catecholamines elevated to an extreme. We therefore investigated the in vitro response of red blood cells from yellowfin tuna (Thunnus albacares) and skipjack tuna (Katsuwonus pelamis) to catecholamines. Tuna red blood cells had a typical response to catecholamines, indicated by a rapid decrease in plasma pH. Amiloride reduced the response, whereas 4,4'diisothiocyanatostilbene-2,2'-disulphonic acid enhanced both the decrease in plasma pH and the increase in intracellular pH. Changes in plasma [Na+], [Cl-], and [K+] were consistent with the hypothesis that tuna red blood cells have a Na+/H+ antiporter similar to that described for other teleost red blood cells. Red blood cells from both tuna species were more responsive to noradrenaline than adrenaline. At identical catecholamine concentrations, the decrease in plasma pH was greater in skipjack tuna blood, the more active of the two tuna species. Based on changes in plasma pH, the response of red blood cells to catecholamines from both tuna species was less than that of rainbow trout (Oncorhynchus mykiss) red blood cells, but greater than that of cod (Gadus morhua) red blood cells. Noradrenaline had no measurable influence on the O2 affinity of skipjack tuna blood and only slightly increased the O2

  10. ²¹⁰Po, Cd and Pb distribution and biomagnification in the yellowfin tuna Thunnus albacares and skipjack tuna Katsuwonus pelamis from the Eastern Pacific.

    PubMed

    Ruelas-Inzunza, J; Soto-Jiménez, M F; Ruiz-Fernández, A C; Ramos-Osuna, M; Mones-Saucedo, J; Páez-Osuna, F

    2014-10-15

    We measured Cd and Pb in the muscle and stomach contents of Thunnus albacares and Katsuwonus pelamis to define the distribution of the elements in the tissues and their degrees of biomagnification. (210)Po was measured in the livers of both species and compared to the results of similar studies. The trophic position of the tuna species was determined by N isotope measurements. The average activity of (210)Po in the liver ranged from 119 to 157 (Bq kg(-1) wet weight) in K. pelamis and T. albacares. The trophic position of T. albacares (4.60) was higher than that of K. pelamis (3.94). The Cd content of the muscle increased significantly with the trophic position of the tuna. δ(13)C in T. albacares and K. pelamis varied, with values of 3.13 and 1.88‰, respectively. The δ(15)N values in yellowfin tuna were higher than in skipjack tuna. The trophic position of T. albacares (4.60 ± 0.67) was therefore more elevated than that of K. pelamis (3.94 ± 1.06). Pb was biomagnified in T. albacares (transfer factor=1.46). PMID:25152180

  11. [Spatial-temporal distribution of bigeye tuna Thunnus obesus in the tropical Atlantic Ocean based on Argo data].

    PubMed

    Yang, Sheng-long; Jin, Shao-fei; Hua, Cheng-jun; Dai, Yang

    2015-02-01

    In order to analyze the correlation between spatial-temporal distribution of the bigeye tuna ( Thunnus obesus) and subsurface factors, the study explored the isothermal distribution of subsurface temperatures in the bigeye tuna fishing grounds in the tropical Atlantic Ocean, and built up the spatial overlay chart of the isothermal lines of 9, 12, 13 and 15 °C and monthly CPUE (catch per unit effort) from bigeye tuna long-lines. The results showed that the bigeye tuna mainly distributed in the water layer (150-450 m) below the lower boundary depth of thermocline. At the isothermal line of 12 °C, the bigeye tuna mainly lived in the water layer of 190-260 m, while few individuals were found at water depth more than 400 m. As to the 13 °C isothermal line, high CPUE often appeared at water depth less than 250 m, mainly between 150-230 m, while no CPUE appeared at water depth more than 300 m. The optimum range of subsurface factors calculated by frequency analysis and empirical cumulative distribution function (ECDF) exhibited that the optimum depth range of 12 °C isothermal depth was 190-260 m and the 13 °C isothermal depth was 160-240 m, while the optimum depth difference range of 12 °C isothermal depth was -10 to 100 m and the 13 °C isothermal depth was -40 to 60 m. The study explored the optimum range of subsurface factors (water temperature and depth) that drive horizontal and vertical distribution of bigeye tuna. The preliminary result would help to discover the central fishing ground, instruct fishing depth, and provide theoretical and practical references for the longline production and resource management of bigeye tuna in the Atlantic Ocean. PMID:26094479

  12. Tracking multiple pathways of waste from a northern bluefin tuna farm in a marine-coastal area.

    PubMed

    Vizzini, Salvatrice; Mazzola, Antonio

    2012-06-01

    Aquaculture of bluefin tuna in Mediterranean coastal waters has generated growing concern about the negative environmental effects. In the present isotopic study we examined the dispersal and fate of organic matter derived from a Mediterranean tuna farm in the surrounding environment. An overall enrichment in the heavy nitrogen isotope was found in the feed and in farmed tunas, indicating the input of isotopically traceable organic matter in the system. Waste was clearly traceable in the water column up to 1000 m from the cages, while only slight accumulation occurred in the sediment just below the cages. Waste was isotopically shown also to contribute to the diet of demersal and benthopelagic wild fish collected around the cages. As a result, waste undertook multiple pathways. In the water column its was diluted and dispersed due to hydrodynamism, which prevented great accumulation of aquaculture-derived organic matter in sediments. In addition, biological constraints such as benthopelagic and demersal fish further prevented organic matter accumulation through the benthic trophic route. PMID:22464398

  13. Blood volume, plasma volume and circulation time in a high-energy-demand teleost, the yellowfin tuna (Thunnus albacares)

    PubMed

    Brill; Cousins; Jones; p

    1998-06-01

    We measured red cell space with 51Cr-labeled red blood cells, and dextran space with 500 kDa fluorescein-isothiocyanate-labeled dextran (FITC-dextran), in two groups of yellowfin tuna (Thunnus albacares). Red cell space was 13.8+/-0.7 ml kg-1 (mean +/- s.e.m.) Assuming a whole-body hematocrit equal to the hematocrit measured at the ventral aortic sampling site and no significant sequestering of 51Cr-labeled red blood cells by the spleen, blood volume was 46. 7+/-2.2 ml kg-1. This is within the range reported for most other teleosts (30-70 ml kg-1), but well below that previously reported for albacore (Thunnus alalunga, 82-197 ml kg-1). Plasma volume within the primary circulatory system (calculated from the 51Cr-labeled red blood cell data) was 32.9+/-2.3 ml kg-1. Dextran space was 37.0+/-3.7 ml kg-1. Because 500 kDa FITC-dextran appeared to remain within the vascular space, these data imply that the volume of the secondary circulatory system of yellowfin tuna is small, and its exact volume is not measurable by our methods. Although blood volume is not exceptional, circulation time (blood volume/cardiac output) is clearly shorter in yellowfin tuna than in other active teleosts. In a 1 kg yellowfin tuna, circulation time is approximately 0.4 min (47 ml kg-1/115 ml min-1 kg-1) compared with 1. 3 min (46 ml kg-1/35 ml min-1 kg-1) in yellowtail (Seriola quinqueradiata) and 1.9 min (35 ml kg-1/18 ml min-1 kg-1) in rainbow trout (Oncorhynchus mykiss). In air-breathing vertebrates, high metabolic rates are necessarily correlated with short circulation times. Our data are the first to imply that a similar relationship occurs in fishes. PMID:9450974

  14. Characterization of the ribosomal RNA gene of Kudoa neothunni (Myxosporea: Multivalvulida) in tunas (Thunnus spp.) and Kudoa scomberi n. sp. in a chub mackerel (Scomber japonicus).

    PubMed

    Li, Ying-Chun; Sato, Hiroshi; Tanaka, Shuhei; Ohnishi, Takahiro; Kamata, Yoichi; Sugita-Konishi, Yoshiko

    2013-05-01

    Kudoa neothunni is the first described Kudoa species having six shell valves and polar capsules, previously assigned to the genus Hexacapsula Arai and Matsumoto, 1953. Since its genetic analyses remain to be conducted, the present study characterizes the ribosomal RNA gene (rDNA) using two isolates from a yellowfin tuna (Thunnus albacares) with post-harvest myoliquefaction and a northern bluefin tuna (Thunnus thynnus) without tissue degradation. Spores of the two isolates localized in the myofiber of trunk muscles, forming pseudocysts, and showed typical morphology of K. neothunni with six equal-sized shell valves radially arranged in apical view: spores (n = 15) measuring 9.5-11.4 μm in width, 7.3-8.6 μm in suture width, 8.9-10.9 μm in thickness, and 7.3-7.7 μm in length; and polar capsules measuring 3.6-4.1 μm by 1.8-2.3 μm. In lateral view, the spores were pyramidal in shape without apical protrusions. Their 18S and 5.8S rDNA sequences were essentially identical, but variations in the ITS1 (62.4 % similarity across 757-bp length), ITS2 (66.9 % similarity across 599-bp length), and 28S (99.0 % similarity across 2,245-bp length) rDNA regions existed between the two isolates. On phylogenetic trees based on the 18S or 28S rDNA sequence, K. neothunni formed a clade with Kudoa spp. with more than four shell valves and polar capsules, particularly K. grammatorcyni and K. scomberomori. Semiquadrate spores of a kudoid species with four shell valves and polar capsules were detected from minute cysts (0.30-0.75 mm by 0.20-0.40 mm) embedded in the trunk muscle of a chub mackerel (Scomber japonicus) fished in the Sea of Japan. Morphologically, it resembled K. caudata described from a chub mackerel fished in the southeastern Pacific Ocean off Peru; however, it lacked filamentous projections on the shell valves of spores. Additionally, it morphologically resembled K. thunni described from a yellowfin tuna also fished in the Pacific Ocean; spores (n

  15. Reproductive Dynamics and Potential Annual Fecundity of South Pacific Albacore Tuna (Thunnus alalunga)

    PubMed Central

    Farley, Jessica H.; Williams, Ashley J.; Hoyle, Simon D.; Davies, Campbell R.; Nicol, Simon J.

    2013-01-01

    The reproductive biology of albacore tuna, Thunnus alalunga, in the South Pacific Ocean was investigated with samples collected during broad-scale sampling between 2006 and 2011. Histology was done in a single laboratory according to standard protocols and the data analysed using generalized linear mixed-effects models. The sex ratio of albacore was female biased for fish smaller than approximately 60 cm FL and between 85 and 95 cm, and progressively more male biased above 95 cm FL. Spawning activity was synchronised across the region between 10°S and 25°S during the austral spring and summer where sea surface temperatures were ≥24 °C. The average gonad index varied among regions, with fish in easterly longitudes having heavier gonads for their size than fish in westerly longitudes. Albacore, while capable of spawning daily, on average spawn every 1.3 days during the peak spawning months of October to December. Spawning occurs around midnight and the early hours of the morning. Regional variation in spawning frequency and batch fecundity were not significant. The proportion of active females and the spawning fraction increased with length and age, and mature small and young fish were less active at either end of the spawning season than larger, older fish. Batch fecundity estimates ranged from 0.26 to 2.83 million oocytes with a mean relative batch fecundity of 64.4 oocytes per gram of body weight. Predicted batch fecundity and potential annual fecundity increased with both length and age. This extensive set of reproductive parameter estimates provides many of the first quantitative estimates for this population and will substantially improve the quality of biological inputs to the stock assessment for South Pacific albacore. PMID:23565258

  16. Reproductive biology of female bigeye tuna Thunnus obesus in the western Pacific Ocean.

    PubMed

    Sun, C L; Yeh, S Z; Chang, Y J; Chang, H Y; Chu, S L

    2013-08-01

    The reproductive biology of female bigeye tuna Thunnus obesus was assessed by examining 888 fish (ranging from 84·9 to 174·4 cm fork length, LF ) caught by Taiwanese offshore longliners in the western Pacific Ocean from November 1997 to November 1998 and November to December 1999 and 258 gonad samples from these fish. The overall sex ratio of the catch during the sampling differed significantly from 0·5, but males were predominant in sizes >140 cm LF . Reproductive activity (assessed by histology), a gonado-somatic index, and the size-frequency distributions of whole oocytes indicated that spawning occurred throughout the year and the major spawning season appeared to be from February to September. The estimated sizes at 50% maturity (LF50 ) of females was 102·85 cm (95% c.i.: 90·79-110·21 cm) and the smallest mature female was 99·7 cm LF . They are multiple spawners and oocytes develop asynchronously. The proportion of mature (0·63) and reproductively active (0·70) females with ovaries containing postovulatory follicles indicated that they spawn almost daily. Batch fecundity for 15 females with the most advanced oocytes (>730 µm) ranged from 0·84 to 8·56 million eggs (mean ± s.d. = 3·06 ± 2·09). The relationships between batch fecundity (FB , in millions of eggs) and LF (cm) and round mass (MR , kg) were FB=9·91×10-14LF6·38 (r(2)  = 0·84) and FB=8·89×10-4MR2·05 (r(2)  = 0·80), respectively. The parameters estimated in this study are key information for stock assessments of T. obesus in the western Pacific Ocean and will contribute to the conservation and sustainable yield of this species. PMID:23902305

  17. Reproductive dynamics and potential annual fecundity of South Pacific albacore tuna (Thunnus alalunga).

    PubMed

    Farley, Jessica H; Williams, Ashley J; Hoyle, Simon D; Davies, Campbell R; Nicol, Simon J

    2013-01-01

    The reproductive biology of albacore tuna, Thunnus alalunga, in the South Pacific Ocean was investigated with samples collected during broad-scale sampling between 2006 and 2011. Histology was done in a single laboratory according to standard protocols and the data analysed using generalized linear mixed-effects models. The sex ratio of albacore was female biased for fish smaller than approximately 60 cm FL and between 85 and 95 cm, and progressively more male biased above 95 cm FL. Spawning activity was synchronised across the region between 10°S and 25°S during the austral spring and summer where sea surface temperatures were ≥24 °C. The average gonad index varied among regions, with fish in easterly longitudes having heavier gonads for their size than fish in westerly longitudes. Albacore, while capable of spawning daily, on average spawn every 1.3 days during the peak spawning months of October to December. Spawning occurs around midnight and the early hours of the morning. Regional variation in spawning frequency and batch fecundity were not significant. The proportion of active females and the spawning fraction increased with length and age, and mature small and young fish were less active at either end of the spawning season than larger, older fish. Batch fecundity estimates ranged from 0.26 to 2.83 million oocytes with a mean relative batch fecundity of 64.4 oocytes per gram of body weight. Predicted batch fecundity and potential annual fecundity increased with both length and age. This extensive set of reproductive parameter estimates provides many of the first quantitative estimates for this population and will substantially improve the quality of biological inputs to the stock assessment for South Pacific albacore. PMID:23565258

  18. Vertical behavior and diet of albacore tuna (Thunnus alalunga) vary with latitude in the South Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Williams, Ashley J.; Allain, Valerie; Nicol, Simon J.; Evans, Karen J.; Hoyle, Simon D.; Dupoux, Cyndie; Vourey, Elodie; Dubosc, Jeff

    2015-03-01

    Albacore tuna (Thunnus alalunga) are an important upper tropic-level oceanic predator with a circum-global distribution. Little is known of the movements and diet of albacore tuna in the South Pacific Ocean and how variability in both might influence the vulnerability of albacore tuna to fisheries across their range. We coupled data derived from satellite-tagged albacore tuna with stomach samples collected from individuals at the same locations to characterize the vertical behavior, thermal and dietary habits of albacore tuna at tropical (New Caledonia and Tonga) and temperate (New Zealand) latitudes. A total of 18 pop-up satellite archival tags deployed on albacore tuna remained attached for 0-50 days. Position estimates, calculated from 11 tags, described short-term movements of predominantly less than 500 km, although one fish moved more than 1000 km over a period of 50 days. Vertical behavior and diet differed substantially between tropical and temperate latitudes. At tropical latitudes, albacore tuna showed a distinct diel pattern in vertical habitat use, occupying shallower, warmer waters above the mixed layer depth (MLD) at night, and deeper, cooler waters below the MLD during the day. In contrast, there was little evidence of a diel pattern of vertical behavior in albacore tuna at temperate latitudes, with fish limited to shallow waters above the MLD almost all of the time. Spatial patterns of species composition in stomach contents were consistent with vertical movement patterns, with significantly more deepwater prey species consumed in tropical waters than in temperate waters. Albacore in tropical waters also consumed significantly greater diversities of prey than in temperate waters, predominately preying on fish species, whereas those in temperate waters predominately preyed on crustacea. Our results indicate that the vertical distribution of albacore is constrained either by thermal preferences with diet reflecting these preferences, by the vertical

  19. Total and methylmercury residues in tuna-fish from the Mediterranean sea.

    PubMed

    Storelli, M M; Stuffler, R Giacominelli; Marcotrigiano, G O

    2002-08-01

    This study was carried out to determine the current levels of total mercury and methylmercury in the muscle tissue of albacore (Thunnus alalunga) and bluefin tuna (Thunnus thynnus) caught in the Mediterranean sea with the purpose of ascertaining whether the concentrations exceeded the maximum level fixed by the European Commission Decision. Total mercury concentrations ranged from 0.84 to 1.45 mg kg(-1) w.w. (av. 1.17 mg kg(-1) w.w.) and from 0.16 to 2.59 mg kg(-1) (av. 1.18 mg kg(-1) w.w.) in the muscle of albacore and bluefin tuna, respectively. In 78.6% of albacore and in 61.1% of bluefin tuna analysed, total mercury concentrations exceeded the maximum level fixed by the European Commission Decision (Hg = 1 micro g g(-1) wet wt). In the two species, mercury was present almost completely in the methylated form, with percentages between 77 and 100% (av. 91.3%) in albacore and between 75 and 100% (av. 91%) in bluefin-tuna. In order to assess the potential health impact, the estimated weekly intake was calculated. The estimated weekly intake was far above the established Provisional Tolerable Weekly Intake for both species. PMID:12227935

  20. Persistent Organic Pollutants in albacore tuna (Thunnus alalunga) from Reunion Island (Southwest Indian Ocean) and South Africa in relation to biological and trophic characteristics.

    PubMed

    Munschy, C; Bodin, N; Potier, M; Héas-Moisan, K; Pollono, C; Degroote, M; West, W; Hollanda, S J; Puech, A; Bourjea, J; Nikolic, N

    2016-07-01

    The contamination of albacore tuna (Thunnus alalunga) by Persistent Organic Pollutants (POPs), namely polychlorinated biphenyls (PCBs) and dichlorodiphenyl-trichloroethane (DDT), was investigated in individuals collected from Reunion Island (RI) and South Africa's (SA) southern coastlines in 2013, in relation to biological parameters and feeding ecology. The results showed lower PCB and DDT concentrations than those previously reported in various tuna species worldwide. A predominance of DDTs over PCBs was revealed, reflecting continuing inputs of DDT. Tuna collected from SA exhibited higher contamination levels than those from RI, related to higher dietary inputs and higher total lipid content. Greater variability in contamination levels and profiles was identified in tuna from RI, explained by a higher diversity of prey and more individualistic foraging behaviour. PCB and DDT contamination levels and profiles varied significantly in tuna from the two investigated areas, probably reflecting exposure to different sources of contamination. PMID:27084988

  1. Purification and characterization of YFGAP, a GAPDH-related novel antimicrobial peptide, from the skin of yellowfin tuna, Thunnus albacares.

    PubMed

    Seo, Jung-Kil; Lee, Min Jeong; Go, Hye-Jin; Park, Tae Hyun; Park, Nam Gyu

    2012-10-01

    A 3.4 kDa of antimicrobial peptide was purified from an acidified skin extract of the yellowfin tuna, Thunnus albacares, by preparative acid-urea-polyacrylamide gel electrophoresis and C(18) reversed-phase HPLC. A comparison of the N-terminal amino acid sequence of the purified peptide with that of other known polypeptides revealed high homology with the N-terminus of glyceraldehyde-3-phosphate dehydrogenase (GAPDH); thus, this peptide was designated as the yellowfin tuna GAPDH-related antimicrobial peptide (YFGAP). YFGAP showed potent antimicrobial activity against Gram-positive bacteria, such as Bacillus subtilis, Micrococcus luteus, and Streptococcus iniae (minimal effective concentrations [MECs], 1.2-17.0 μg/mL), and Gram-negative bacteria, such as Aeromonas hydrophila, Escherichia coli D31, and Vibrio parahaemolyticus (MECs, 3.1-12.0 μg/mL) without significant hemolytic activity. According to the secondary structural prediction and the homology modeling, this peptide forms an amphipathic structure and consists of three secondary structural motifs including one α-helix and two parallel β-strands. This peptide did not show membrane permeabilization ability and its activity was bacteriostatic rather than bactericidal. This is the first report of the isolation of an antimicrobial peptide from a tuna species and the first description of the antimicrobial function of the N-terminus of GAPDH of an animal species. PMID:22771964

  2. Methodological assessment of 2b-RAD genotyping technique for population structure inferences in yellowfin tuna (Thunnus albacares).

    PubMed

    Pecoraro, Carlo; Babbucci, Massimiliano; Villamor, Adriana; Franch, Rafaella; Papetti, Chiara; Leroy, Bruno; Ortega-Garcia, Sofia; Muir, Jeff; Rooker, Jay; Arocha, Freddy; Murua, Hilario; Zudaire, Iker; Chassot, Emmanuel; Bodin, Nathalie; Tinti, Fausto; Bargelloni, Luca; Cariani, Alessia

    2016-02-01

    Global population genetic structure of yellowfin tuna (Thunnus albacares) is still poorly understood despite its relevance for the tuna fishery industry. Low levels of genetic differentiation among oceans speak in favour of the existence of a single panmictic population worldwide of this highly migratory fish. However, recent studies indicated genetic structuring at a much smaller geographic scales than previously considered, pointing out that YFT population genetic structure has not been properly assessed so far. In this study, we demonstrated for the first time, the utility of 2b-RAD genotyping technique for investigating population genetic diversity and differentiation in high gene-flow species. Running de novo pipeline in Stacks, a total of 6772 high-quality genome-wide SNPs were identified across Atlantic, Indian and Pacific population samples representing all major distribution areas. Preliminary analyses showed shallow but significant population structure among oceans (FST=0.0273; P-value<0.01). Discriminant Analysis of Principal Components endorsed the presence of genetically discrete yellowfin tuna populations among three oceanic pools. Although such evidence needs to be corroborated by increasing sample size, these results showed the efficiency of this genotyping technique in assessing genetic divergence in a marine fish with high dispersal potential. PMID:26711352

  3. Benefits and risks associated with consumption of raw, cooked, and canned tuna (Thunnus spp.) based on the bioaccessibility of selenium and methylmercury.

    PubMed

    Afonso, C; Costa, S; Cardoso, C; Oliveira, R; Lourenço, H M; Viula, A; Batista, I; Coelho, I; Nunes, M L

    2015-11-01

    The Se, Hg, and methylmercury (MeHg) levels in raw, cooked (boiled and grilled), and canned tuna (Thunnus spp.) were determined before and after an in vitro digestion, thereby enabling the calculation of the respective bioaccessibility percentages. A risk-benefit evaluation of raw and canned tuna on the basis of the Se and MeHg data was performed. Selenium bioaccessibility was high in tuna, though slightly lower in canned than in raw products. Mercury levels were high in raw and cooked tuna. Hg bioaccessibility percentages were low (39-48%) in the cooked tuna and even lower (<20%) in canned tuna. For the bioaccessible fraction, all molar Se:MeHg ratios were higher than one (between 10 and 74). A probabilistic assessment of MeHg risk vs Se benefit showed that while a weekly meal of canned tuna presents very low risk, raw, boiled, and grilled tuna consumption should not exceed a monthly meal, at least, for pregnant and nursing women. PMID:25962922

  4. Habitat overlap between southern bluefin tuna and yellowfin tuna in the east coast longline fishery - implications for present and future spatial management

    NASA Astrophysics Data System (ADS)

    Hartog, Jason R.; Hobday, Alistair J.; Matear, Richard; Feng, Ming

    2011-03-01

    Southern bluefin tuna (SBT) are presently a quota-managed species in the multi-species eastern Australian tuna and billfish longline fishery (ETBF). Capture of SBT is regulated by quota, as is access to regions likely to contain SBT. A habitat prediction model combining data from an ocean model and pop-up satellite archival tags is used to define habitat zones based on the probability of SBT occurrence. These habitat zones are used by fishery managers to restrict access by ETBF fishers to SBT habitat during a May-November management season. The zones display a distinct seasonal cycle driven by the seasonal southward expansion and northward contraction of the East Australia Current (EAC) and as a result access by fishers to particular ocean regions changes seasonally. This species also overlaps with the commercially valuable yellowfin tuna (YFT), thus, we modified the SBT model to generate YFT habitat predictions in order to investigate habitat overlap between SBT and YFT. There is seasonal variation in the overlap of the core habitat between these two species, with overlap early (May-Jul) in the management season and habitat separation occurring towards the end (Aug-Nov). The EAC is one of the fastest warming ocean regions in the southern hemisphere. To consider the future change in distribution of these two species compared to the present and to explore the potential impact on fishers and managers of the future, we use future ocean predictions from the CSIRO Bluelink ocean model for the year 2064 to generate habitat predictions. As the ocean warms on the east coast of Australia and the EAC extends southward, our model predicts the suitable habitat for SBT and YFT will move further south. There was an increase in the overlap of SBT and YFT habitat throughout the management season, due to regional variation of each species' habitat. These results illustrate that a management tradeoff exists between restricting fisher access to SBT habitat and allowing access to YFT

  5. Mercury accumulation in Yellowfin tuna (Thunnus albacares) with regards to muscle type, muscle position and fish size.

    PubMed

    Bosch, Adina C; O'Neill, Bernadette; Sigge, Gunnar O; Kerwath, Sven E; Hoffman, Louwrens C

    2016-01-01

    The concentrations and relationships between individual mercury species and total mercury were investigated in different muscle parts and sizes of Yellowfin tuna (Thunnus albacares). Fourteen Yellowfin tuna caught in the South Atlantic off the coast of South Africa had an average total Hg (tHg) concentration of 0.77 mg/kg wet weight. No differences were detected (p > 0.05) in tHg, MethylHg (MeHg) or inorganic Hg (iHg) accumulation among the four white muscle portions across the carcass, but both tHg and iHg were found in higher concentrations (p < 0.001) in dark muscle than white muscle. Positive linear correlations with fish weight were found for both tHg (r = 0.79, p < 0.001) and MeHg (r = 0.75, p < 0.001) concentrations. A prediction model was formulated to calculate toxic MeHg concentrations from measured tHg concentrations and fish weight (cMeHg = 0.073 + 1.365 · tHg-0.008 · w). As sampling sites and subsampling methods could affect toxicity measurements, we provide recommendations for sampling guidelines. PMID:26212981

  6. Heavy metals in yellowfin tuna (Thunnus albacares) and common dolphinfish (Coryphaena hippurus) landed on the Ecuadorian coast.

    PubMed

    Araújo, Cristiano V M; Cedeño-Macias, Luis A

    2016-01-15

    Heavy metals are contaminants of great environmental concern due to their multiple origins (natural and anthropogenic), the ability to accumulate in organs and tissues, and the deleterious effects they can cause in organisms. Studies on the accumulation of metals in seafood, such as fish, have increased in importance due to the risk for human health when consuming fish contaminated by metals. The present work was aimed at verifying the concentrations of cadmium (Cd), mercury (Hg) and lead (Pb) in the muscular tissue and liver of yellowfin tuna (Thunnus albacares) and common dolphinfish (Coryphaena hippurus) from the Eastern Pacific Ocean landed in Manta city, Ecuador. Samples were analyzed by inductively coupled plasma mass spectroscopy (ICP-MS). Around half of the muscle samples of both species presented levels of Cd and Hg above the limits considered safe for human consumption established by the European Union. For Pb,most of the muscle samples were considered acceptable for consumption. Results indicate that both species should be consumed with some caution. Considering the tolerable weekly intake recommended for adults by the World Health Organization, results indicate that Hg is the main metal that limits the consumption of yellowfin tuna and common dolphinfish, with a recommended maximum ingestion, respectively, of 191 and 178 g per week for an adult.c PMID:26406109

  7. Intraspecific rDNA variability of Kudoa sp. isolates from blackfin tuna (Thunnus atlanticus) suggests K. crumena and K. thunni are synonymous

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Numerous myxozoan cysts (~1 mm) were found in the musculature of blackfin tuna (Thunnus atlanticus) harvested off the Caribbean island of St. Kitts. Myxospores were consistent with quadrate members of the Kudoidae, measuring 8.8 (8.2-9.4) µm wide, 7.3 (6.6-8.3) µm thick and 6.2 (5.8-6.9) µm long wi...

  8. 77 FR 15712 - Atlantic Highly Migratory Species; 2012 Atlantic Bluefin Tuna Quota Specifications

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-16

    ... implementing the BFT quotas and Atlantic tuna fisheries management measures (76 FR 39019, July 5, 2011), NMFS... Federal Register (64 FR 29090) final regulations, effective July 1, 1999, implementing the Fishery... in the Federal Register (71 FR 58058) a final rule, effective November 1, 2006, implementing the...

  9. 50 CFR 660.702 - Definitions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... or bonito shark (Isurus oxyrinchus) blue shark (Prionace glauca) Tunas: north Pacific albacore (Thunnus alalunga) yellowfin tuna (Thunnus albacares) bigeye tuna (Thunnus obesus) skipjack tuna (Katsuwonus pelamis) Pacific bluefin tuna (Thunnus orientalis) Other: dorado or dolphinfish...

  10. 50 CFR 660.702 - Definitions.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... or bonito shark (Isurus oxyrinchus) blue shark (Prionace glauca) Tunas: north Pacific albacore (Thunnus alalunga) yellowfin tuna (Thunnus albacares) bigeye tuna (Thunnus obesus) skipjack tuna (Katsuwonus pelamis) Pacific bluefin tuna (Thunnus orientalis) Other: dorado or dolphinfish...

  11. 50 CFR 660.702 - Definitions.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... or bonito shark (Isurus oxyrinchus) blue shark (Prionace glauca) Tunas: north Pacific albacore (Thunnus alalunga) yellowfin tuna (Thunnus albacares) bigeye tuna (Thunnus obesus) skipjack tuna (Katsuwonus pelamis) Pacific bluefin tuna (Thunnus orientalis) Other: dorado or dolphinfish...

  12. 50 CFR 660.702 - Definitions.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... shark (Isurus oxyrinchus) blue shark (Prionace glauca) Tunas: north Pacific albacore (Thunnus alalunga) yellowfin tuna (Thunnus albacares) bigeye tuna (Thunnus obesus) skipjack tuna (Katsuwonus pelamis) northern bluefin tuna (Thunnus orientalis) Other: dorado or dolphinfish (Coryphaena hippurus) Highly...

  13. Organic and total mercury levels in bigeye tuna, Thunnus obesus, harvested by Taiwanese fishing vessels in the Atlantic and Indian Oceans.

    PubMed

    Chen, M H; Teng, P Y; Chen, C Y; Hsu, C C

    2011-01-01

    Muscle samples of 121 and 110 bigeye tuna (Thunnus obesus) caught by Taiwanese long-line fishing vessels in the Atlantic and Indian Oceans, respectively, were used to analyze total mercury (THg) and organic mercury (OHg) content. The overall THg and OHg concentrations were 0.786 ± 0.386 (0.214-3.133) and 0.595 ± 0.238 (0.143-2.222) mg kg⁻¹ wet weight, respectively, similar to the results of previous studies. Our findings, however, reflected the highest THg and OHg concentrations for the species in each ocean among the published data. Mean THg and OHg concentrations in Atlantic tuna were significantly (p < 0.05) higher than those in Indian tuna. Two of 121 samples of tuna from the Atlantic Ocean, but no samples from the Indian Ocean, had levels of OHg above 2 mg kg⁻¹ wet weight set by the Department of Health Taiwan, and 13 of 121 samples of tuna from the Atlantic Ocean and three of 110 samples from the Indian Ocean had levels of OHg above 1 mg kg⁻¹ wet weight set by US FDA and WHO. Accordingly, for adult Taiwanese men and women with average body weight of 65 and 55 kg, respectively, the maximum allowable weekly intake of bigeye tuna is suggested to be 170 and 145 g, respectively. PMID:24779657

  14. Differential heating and cooling rates in bigeye tuna (Thunnus obesus Lowe): a model of non-steady state heat exchange.

    PubMed

    Malte, Hans; Larsen, Christina; Musyl, Michael; Brill, Richard

    2007-08-01

    We analyzed water temperature, visceral cavity temperature and depth data from archival tags retrieved from bigeye tuna (Thunnus obesus) at liberty in the central Pacific for up to 57 days using a mathematical model of heat exchange. Our model took into account the transfer of heat between the portions of the myotomes comprising red muscle fibers adjacent to the spinal column and served by vascular counter current heat exchanges (henceforth referred to as ;red muscle') and the water, as well as between the red muscle and the temperature sensor of the archival tags in the visceral cavity. Our model successfully predicted the recorded visceral cavity temperatures during vertical excursions provided that the rate constants for heat transfer between the ambient water and the red muscle during cooling (k(low)) and those during heating (k(high)) were very dissimilar. Least-squares fitting of k(low) and k(high) for the entire period that the fish were at liberty yielded values generally in the ranges 0.02-0.04 min(-1) and 0.2-0.6 min(-1) (respectively), with an average ratio k(high)/k(low) of approximately 12. Our results confirmed those from previous studies showing that bigeye tuna have extensive physiological thermoregulatory abilities probably exerted through changes of blood flow patterns that controlled the efficiency of vascular countercurrent heat exchanges. There was a small but significant negative correlation between k(low) and size, whereas there was no correlation between k(high) and size. The maximum swimming speeds during vertical excursions (calculated from the pressure data) occurred midway during ascents and averaged approximately 2 FL s(-1) (where FL=fork length), although speeds as high approximately 4-7 FL s(-1) were also noted. PMID:17644676

  15. Quality assessment of ice-stored tropical yellowfin tuna (Thunnus albacares) and influence of vacuum and modified atmosphere packaging.

    PubMed

    Silbande, Adèle; Adenet, Sandra; Smith-Ravin, Juliette; Joffraud, Jean-Jacques; Rochefort, Katia; Leroi, Françoise

    2016-12-01

    Metagenomic, microbial, chemical and sensory analyses of Thunnus albacares from Martinique stored in ice (AIR - 0 °C), vacuum (VP - 4/8 °C) and modified atmosphere packaging (MAP - 4/8 °C) (70% CO2 - 30% O2) were carried out. The organoleptic rejection of AIR tuna was observed at day 13 when total bacterial counts equaled 10(6)-10(7) CFU g(-1). No extension of shelf-life was provided by VP and MAP. According to 16S rRNA gene sequence analyzed by Illumina MiSeq and PCR-TTGE, Rhodanobacter terrae was the main species of the freshly caught tuna. At the sensory rejection time, Brochothrix thermosphacta and Pseudomonas dominated the AIR products while B. thermosphacta alone or a mix of B. thermosphacta, Enterobacteriaceae and lactic acid bacteria (LAB) dominated the microbiota of MAP and VP products, respectively. The pH value remained stable in all trials, ranging from 5.77 to 5.97. Total volatile basic nitrogen (TVBN) and trimethylamine (TMA-N) concentrations were weak and not significantly different between batches. Lipid oxidation increased in the samples containing O2 (MAP > AIR). The initial concentration of histamine was high (75-78 mg kg(-1)) and stable up to 8 days but then significantly decreased in all trials to reach 25-30 mg kg(-1), probably due to the presence of histamine-decomposing bacteria. PMID:27554147

  16. Potential impacts of climate change on the distribution of longline catches of yellowfin tuna (Thunnus albacares) in the Tasman sea

    NASA Astrophysics Data System (ADS)

    Dell, James T.; Wilcox, Chris; Matear, Richard J.; Chamberlain, Matthew A.; Hobday, Alistair J.

    2015-03-01

    The spatial distribution of living marine resources in the Tasman Sea is expected to shift due to the impacts of global climate change. Understanding the most likely future locations of valuable pelagic species will inform the sustainable harvest and management of species such as yellowfin tuna (YFT; Thunnus albacares). We estimate future upper ocean structure in the Tasman Sea, using both historical data and dynamically downscaled ocean projections for the 2060s, and apply a catch distribution model to estimate possible changes to the YFT catch in the eastern Australia domestic longline fishery. Both approaches project that locations with concentrated YFT catch in the Tasman Sea will shift poleward in response to likely climate change. By the 2060s, the core fishing areas are projected to have shifted both poleward and offshore of existing high catch areas. Shifts in the distribution and hence availability of this species may require future domestic fishing vessels to modify their fishing behaviors, which in turn may require social and economic adjustments.

  17. Spatial and Sex-Specific Variation in Growth of Albacore Tuna (Thunnus alalunga) across the South Pacific Ocean

    PubMed Central

    Williams, Ashley J.; Farley, Jessica H.; Hoyle, Simon D.; Davies, Campbell R.; Nicol, Simon J.

    2012-01-01

    Spatial variation in growth is a common feature of demersal fish populations which often exist as discrete adult sub-populations linked by a pelagic larval stage. However, it remains unclear whether variation in growth occurs at similar spatial scales for populations of highly migratory pelagic species, such as tuna. We examined spatial variation in growth of albacore Thunnus alalunga across 90° of longitude in the South Pacific Ocean from the east coast of Australia to the Pitcairn Islands. Using length-at-age data from a validated ageing method we found evidence for significant variation in length-at-age and growth parameters (L∞ and k) between sexes and across longitudes. Growth trajectories were similar between sexes up until four years of age, after which the length-at-age for males was, on average, greater than that for females. Males reached an average maximum size more than 8 cm larger than females. Length-at-age and growth parameters were consistently greater at more easterly longitudes than at westerly longitudes for both females and males. Our results provide strong evidence that finer spatial structure exists within the South Pacific albacore stock and raises the question of whether the scale of their “highly migratory” nature should be re-assessed. Future stock assessment models for South Pacific albacore should consider sex-specific growth curves and spatial variation in growth within the stock. PMID:22723993

  18. Spatial and sex-specific variation in growth of albacore tuna (Thunnus alalunga) across the South Pacific Ocean.

    PubMed

    Williams, Ashley J; Farley, Jessica H; Hoyle, Simon D; Davies, Campbell R; Nicol, Simon J

    2012-01-01

    Spatial variation in growth is a common feature of demersal fish populations which often exist as discrete adult sub-populations linked by a pelagic larval stage. However, it remains unclear whether variation in growth occurs at similar spatial scales for populations of highly migratory pelagic species, such as tuna. We examined spatial variation in growth of albacore Thunnus alalunga across 90° of longitude in the South Pacific Ocean from the east coast of Australia to the Pitcairn Islands. Using length-at-age data from a validated ageing method we found evidence for significant variation in length-at-age and growth parameters (L(∞) and k) between sexes and across longitudes. Growth trajectories were similar between sexes up until four years of age, after which the length-at-age for males was, on average, greater than that for females. Males reached an average maximum size more than 8 cm larger than females. Length-at-age and growth parameters were consistently greater at more easterly longitudes than at westerly longitudes for both females and males. Our results provide strong evidence that finer spatial structure exists within the South Pacific albacore stock and raises the question of whether the scale of their "highly migratory" nature should be re-assessed. Future stock assessment models for South Pacific albacore should consider sex-specific growth curves and spatial variation in growth within the stock. PMID:22723993

  19. Reproduction of Blackfin tuna Thunnus atlanticus (Perciformes: Scombridae) in Saint Peter and Saint Paul Archipelago, Equatorial Atlantic, Brazil.

    PubMed

    Bezerra, Natalia P A; Fernandes, Cezar A F; Albuquerque, Fernanda V; Pedrosa, Vanessa; Hazin, Fábio; Travassos, Paulo

    2013-09-01

    The reproduction of Blackfin tuna Thunnus atlanticus has been described for coastal regions, and for a long time, this species was considered to be a strictly continental spawner. Recently, this species was observed around a seamount habitat 500 nautical miles Northeast of Brazil, located between South America and Africa. In this study we describe the reproductive biology of Blackfin tuna at Saint Peter and Saint Paul Archipelago (SPSPA). Male and female gonads were sampled from December 2008 to July 2010, and analyzed macro and microscopically. A total of 361 fish were sampled (247 males and 114 females). Males were more common than females, with a sex ratio of 2.2 male:1 female. The fork length (FL) of all sampled specimens ranged from 38 to 98cm, and larger length classes were more frequent in males. It was possible to distinguish six maturity phases for females: immature, developing, spawning capable, actively spawning, regressing and recovering. Five phases were identified for males: immature, developing, spawning capable, actively spawning and recovering. The gonad index (GI) mean monthly values ranged from 6.6 (SD = 4.1) to 58.4 (SD = 34.7) for females, and from 2.6 (SD = 1.3) to 66.2 (SD = 30.4) for males. For both sexes, the largest GI values were observed at the beginning of the first semester of the year. Size at first maturity was estimated at 48cm FL and 55cm FL for females and males respectively. Approximately 80% of the specimens were adults and considered to be in reproductive conditions. Histological analysis of the ovaries and testes showed that most of the specimens were sexually mature and were reproductively active during all months of the year. However, females with mature ovaries, with large amounts of hydrated oocytes and post-ovulatory follicles, were mainly found from December to March, thus these months may constitute the main spawning season in SPSPA. Batch fecundity varied between 272025 and 1,140584 oocytes for 56 and 68 cm FL females

  20. Determination of cadmium, lead and mercury residual levels in meat of canned light tuna (Katsuwonus pelamis and Thunnus albacares) and fresh little tunny (Euthynnus alletteratus) in Libya

    PubMed Central

    Abolghait, S.K.; Garbaj, A.M.

    2015-01-01

    Surveillance for mercury (Hg), lead (Pb) and cadmium (Cd) contamination in tuna products is crucial for consumer food safety. Hg, Pb and Cd contaminants were monitored in a total of 60 specimens of fresh little tunny (Euthynnus alletteratus) and popular brands of skipjack and yellowfin (Katsuwonus pelamis and Thunnus albacares) canned tuna commercially available in Tripoli, Libya. Direct Mercury Analyzer (DMA-80) was implemented for determination of total Hg level and graphite furnace atomic absorption spectrometry (GFAAS) was employed for determination of Cd and Pb concentrations. The results indicated that Hg had the highest concentration level and Cd had the lowest concentration level either in tested canned tuna or fresh little tunny samples. The average concentration of Hg in fresh little tunny samples was 1.185 ± 0.968 mg kg-1 wet weight (ww) and often exceeded the standard permissible limit. In addition, canned yellowfin tuna had the lowest levels of Cd (0.027 ± 0.026 mg kg-1 ww), Pb (0.075 ± 0.071) and Hg (0.163 ± 0.122 mg kg-1 ww). Results of the current surveillance indicated that canned skipjack and yellowfin tuna sold in Tripoli markets show contaminant levels well under the European thresholds adopted for Cd, Pb and Hg. However, consumption of large quantities of Mediterranean little tunny products significantly increases human exposure to the risk of Hg toxicity. PMID:26623379

  1. Determination of cadmium, lead and mercury residual levels in meat of canned light tuna (Katsuwonus pelamis and Thunnus albacares) and fresh little tunny (Euthynnus alletteratus) in Libya.

    PubMed

    Abolghait, S K; Garbaj, A M

    2015-01-01

    Surveillance for mercury (Hg), lead (Pb) and cadmium (Cd) contamination in tuna products is crucial for consumer food safety. Hg, Pb and Cd contaminants were monitored in a total of 60 specimens of fresh little tunny (Euthynnus alletteratus) and popular brands of skipjack and yellowfin (Katsuwonus pelamis and Thunnus albacares) canned tuna commercially available in Tripoli, Libya. Direct Mercury Analyzer (DMA-80) was implemented for determination of total Hg level and graphite furnace atomic absorption spectrometry (GFAAS) was employed for determination of Cd and Pb concentrations. The results indicated that Hg had the highest concentration level and Cd had the lowest concentration level either in tested canned tuna or fresh little tunny samples. The average concentration of Hg in fresh little tunny samples was 1.185 ± 0.968 mg kg(-1) wet weight (ww) and often exceeded the standard permissible limit. In addition, canned yellowfin tuna had the lowest levels of Cd (0.027 ± 0.026 mg kg(-1) ww), Pb (0.075 ± 0.071) and Hg (0.163 ± 0.122 mg kg(-1) ww). Results of the current surveillance indicated that canned skipjack and yellowfin tuna sold in Tripoli markets show contaminant levels well under the European thresholds adopted for Cd, Pb and Hg. However, consumption of large quantities of Mediterranean little tunny products significantly increases human exposure to the risk of Hg toxicity. PMID:26623379

  2. Shifting from marine reserves to maritime zoning for conservation of Pacific bigeye tuna (Thunnus obesus)

    PubMed Central

    Sibert, John; Senina, Inna; Lehodey, Patrick; Hampton, John

    2012-01-01

    Over 50% of the total bigeye tuna (BET) landed in the Western Central Pacific Ocean is caught incidentally in the purse seine fishery and sold for canning at prices less than US$2/kg. The remainder is landed in longline fisheries directed at BET and sold as fresh or frozen tuna at prices greater than US$10/kg. The combined fishing mortality by all gears will soon reduce the BET biomass in the Pacific Ocean to less than that capable of producing maximum sustainable yield. Closure of the high-seas enclaves in 2009 was hailed as a conservation measure, but was not scientifically evaluated before implementation and appears to have had no beneficial effect on the BET stock. A spatially explicit age-structured ecosystem model, SEAPODYM, is used to simulate alternative area-based fishery management policies to conserve bigeye tuna in the Western Central Pacific Ocean. Closing the high-seas enclaves to purse seine fishing has negligible effect on the BET biomass. Fishery management policies that control mortality on both juveniles and adults, through prohibition of fish aggregation devices in the purse seine fishery and restrictions on longline fishing in spawning areas, are the most efficient conservation policies. Large-scale benefits from bigeye conservation measures will become apparent only in the 2030s, assuming timely implementation and minimal effects of climate change. PMID:23064639

  3. Shifting from marine reserves to maritime zoning for conservation of Pacific bigeye tuna (Thunnus obesus).

    PubMed

    Sibert, John; Senina, Inna; Lehodey, Patrick; Hampton, John

    2012-10-30

    Over 50% of the total bigeye tuna (BET) landed in the Western Central Pacific Ocean is caught incidentally in the purse seine fishery and sold for canning at prices less than US$2/kg. The remainder is landed in longline fisheries directed at BET and sold as fresh or frozen tuna at prices greater than US$10/kg. The combined fishing mortality by all gears will soon reduce the BET biomass in the Pacific Ocean to less than that capable of producing maximum sustainable yield. Closure of the high-seas enclaves in 2009 was hailed as a conservation measure, but was not scientifically evaluated before implementation and appears to have had no beneficial effect on the BET stock. A spatially explicit age-structured ecosystem model, SEAPODYM, is used to simulate alternative area-based fishery management policies to conserve bigeye tuna in the Western Central Pacific Ocean. Closing the high-seas enclaves to purse seine fishing has negligible effect on the BET biomass. Fishery management policies that control mortality on both juveniles and adults, through prohibition of fish aggregation devices in the purse seine fishery and restrictions on longline fishing in spawning areas, are the most efficient conservation policies. Large-scale benefits from bigeye conservation measures will become apparent only in the 2030s, assuming timely implementation and minimal effects of climate change. PMID:23064639

  4. Infection of Anisakids Larvae in Long Tail Tuna (Thunnus tonggol) In North Persian Gulf

    PubMed Central

    Eslami, A; Sabokroo, H; Ranjbar- Bahadori, SH

    2011-01-01

    Background The aim of this paper was to study the prevalence and intensity of Anisakids larvae in the long tail tuna fish captured from Iranian shores of Persian Gulf. Methods Different organs including skin, abdominal cavity, stomach and intestinal contents, stomach sub serous tissues, liver, spleen, gonads and 20 grams of muscles of 100 long tail tuna fish (Thannus tonggol) caught from waters of the north parts of Persian Gulf were searched for anisakid nematodes larvae. Twenty grams of around the body cavity muscles were digested in artificial gastric juice. Different organs and digested muscles were examined with naked eyes for the presence of anisakids larvae. The collected larvae were preserved in 70% alcohol containing 5% glycerin, and cleared in lactophenol for identification. Results Our findings revealed that 89% of fish harbored 3rd stage larvae of Anisakis sp. of which 2% were infected with both Anisakis and Raphidascaris. All inspected organs except that of skin were found to be infected, while stomach sub serous tissues were the most infected organ (80%) followed by abdominal cavity (10%), liver (4%), testicle (3%), stomach contents and spleen (2%) and intestinal contents (1%). Intestine and abdominal cavity were the organs harbored Raphidascaris sp. Digested muscles were free of parasite. Mean intensity was low for both species and ranged between 1.5 for Raphidascaris sp. and 3.67 for Anisaki sp. Conclusion Anisakids larvae especially Anisakis are very prevalent in some fish including tunas of Persian Gulf, and consumption of infected fish if it is not properly cooked may lead to human anisakiasis. PMID:22347303

  5. Gonadal histology and serum vitellogenin levels of bigeye tuna Thunnus obesus from the Northern Pacific Ocean--absence of endocrine disruption bio-indicators.

    PubMed

    Hashimoto, Shinya; Kurihara, Ryo; Strüssmann, Carlos Augusto; Yamasaki, Tsugiko; Soyano, Kiyoshi; Hara, Akihiko; Shiraishi, Hiroaki; Morita, Masatoshi

    2003-04-01

    Endocrine disrupting chemicals such as organochlorines have been detected in a large number of marine fish. Histological observation of the gonads, measurement of serum vitellogenin (VTG) level and of liver polychlorinated biphenyl (PCB) content were performed to evaluate the reproductive health and the contamination with endocrine disruptors in bigeye tuna Thunnus obesus, collected in the northern Pacific Ocean in 1999 and 2000. Abnormalities commonly found in species affected by endocrine disruptors such as the presence of oocytes in the testis or elevated serum VTG levels were not found in any of males examined. Both males and females had only small amounts of liver PCB content. The results suggest that currently there is little if any risk of organochlorine contamination or endocrine disruption of gonadal function in bigeye tuna from the northern Pacific Ocean. However, further studies are necessary to evaluate the health status of the open sea fishery resources. PMID:12705919

  6. Gonadogenesis and slow proliferation of germ cells in juveniles of cultured yellowfin tuna, Thunnus albacares.

    PubMed

    Kobayashi, Toru; Honryo, Tomoki; Agawa, Yasuo; Sawada, Yoshifumi; Tapia, Ileana; Macìas, Karla A; Cano, Amado; Scholey, Vernon P; Margulies, Daniel; Yagishita, Naoki

    2015-06-01

    To develop techniques for seedling production of yellowfin tuna, the behavior of primordial germ cells (PGCs) and gonadogenesis were examined at 1-30 days post hatching (dph) using morphometric analysis, histological examination, and in situ hybridization. Immediately after hatching, PGCs were located on the dorsal side of the posterior end of the rectum under the peritoneum of the larvae, and at 3 dph they came into contact with stromal cells. PGCs and stromal cells gradually moved forward from the anus prior to 5 dph. At 7-10 dph, germ cells were surrounded by stromal cells and the gonadal primordia were formed. In individuals collected at 12 dph, PGCs were detected by in situ hybridization using a vasa mRNA probe that is a germ-cell-specific detection marker. The proliferation of germ cells in the gonadal primordia began at 7-10 dph. We observed double the number of germ cells at 30 dph (22 ± 3.2 cells), compared to that at 1 dph (11 ± 2.1 cells). Therefore, based on our data and previous reports, the initial germ cell proliferation of yellowfin tuna is relatively slower than that of other fish species. PMID:26051459

  7. Genetic divergence between Atlantic and Indo-Pacific stocks of bigeye tuna (Thunnus obesus) and admixture around South Africa.

    PubMed

    Chow, S; Okamoto, H; Miyabe, N; Hiramatsu, K; Barut, N

    2000-02-01

    Two mitochondrial DNA segments of the bigeye tuna (Thunnus obesus) were amplified by polymerase chain reaction (PCR), and restriction fragment length polymorphism (RFLP) analyses of these segments were used for the genetic stock study. The variation in a segment flanking the ATPase and COIII genes was low; only two genotypes (alpha and beta) were detected by RsaI digestion. Yet a large difference in the genotype distribution was observed between ocean basin samples. The alpha type predominated in four Atlantic samples, where 178 of 244 individuals were the alpha type. In contrast, only one of 195 individuals collected in the Indo-Pacific was the alpha type? The frequency of the alpha type varied considerably from 0 to 80% among seven samples collected off the Cape of Good Hope. The variation found in the other segment, containing the D-loop region, was much higher; two endonucleases (DpnII and RsaI) detected five genotypes each and 15 composite genotypes. A highly significant difference in genotype frequencies was observed between the Atlantic and Indo-Pacific samples, but no heterogeneity was observed among the four Atlantic or among four Indo-Pacific samples. These results clearly indicate that not only gene flow, but also fish migration, between the Atlantic and Indian Oceans are severely restricted, and that fishes from these distinct stocks are intermingling around South Africa. The simple and diagnostic genetic marker found in this study can be used to estimate mixing ratios between Atlantic and Indian stocks around South Africa. PMID:10672166

  8. Organ blood flow haemodynamics and metabolism of the albacore tuna Thunnus alalunga (Bonnaterre).

    PubMed

    White, F C; Kelly, R; Kemper, S; Schumacker, P T; Gallagher, K R; Laurs, R M

    1988-01-01

    Metabolic haemodynamic, and organ blood flow measurements were made in tabled, partially anaesthetized albacore Thunnus alalunga. Heart rates were 115 +/- 9 beats/min: blood pressure 98/75 mm Hg (systolic/diastolic): cardiac output 36.1 +/- 5 (ml/min/kg): oxygen consumption 3.4 +/- 0.7 (ml O2/min/kg) and cardiac contractility (dP/dt) 6342 +/- 822 mm Hg/s. Organ blood flows were measured with radiolabelled microspheres. The red muscle, kidney, and spleen received the highest flows and the white-muscle the least. There was a flow gradient in the white-muscle with the inner portion near the red-muscle receiving the highest flows. Arterial and venous blood gas measurements showed a reverse temperature effect on arterial PO2 and a P50 of 15.9 Torr corrected to 37 degrees C. Red-muscle temperature was 7 degrees C higher than ambient water temperature. These measurements record the albacore's markedly high cardiovascular capability. PMID:3384072

  9. Biomagnification of mercury and its antagonistic interaction with selenium in yellowfin tuna Thunnus albacares in the trophic web of Baja California Sur, Mexico.

    PubMed

    Ordiano-Flores, Alfredo; Rosíles-Martínez, Rene; Galván-Magaña, Felipe

    2012-12-01

    Mercury and selenium concentrations were determined in muscle of 37 yellowfin tuna (Thunnus albacares) captured aboard of Mexican purse-seiners boats off western coast of Baja California Sur, between Punta Eugenia and Cabo Falso, from October to December 2006. Also, its prey (mainly, jumbo squid Dosidicus gigas and pelagic red crab Pleuroncodes planipes) were analyzed from the stomach contents. All the mercury values obtained were lower that mercury content recommended by standard legal limits for seafood adopted by Mexican norms (typically 0.5-1.0μg g(-1)). Mercury concentrations vary between 0.06 and 0.51μg g(-1) in yellowfin tuna, and from 0.01 to 0.20μg g(-1) in its prey, suggesting that mercury can accumulate in prey tissues and that of their predator. Biomagnification factors (BMF) between predator-prey associations were calculated. The BMFs were >1, indicating that mercury biomagnifies along the food web of yellowfin tuna. In all species studied there was a molar excess of selenium over mercury. The rank order of mean selenium/mercury molar ratios was for pufferfish (42.62)> diamond squid (15.09)>yellowfin tuna (10.29)>pelagic red crab (10.05)>panama lightfish (9.54)> jumbo squid (8.91). The selenium health benefit value (Se-HBV) was calculated to have an improved understanding of the health benefits and risk of fish consumption. PMID:23059106

  10. Genetic structuring and migration patterns of Atlantic bigeye tuna, Thunnus obesus (Lowe, 1839)

    PubMed Central

    2008-01-01

    Background Large pelagic fishes are generally thought to have little population genetic structuring based on their cosmopolitan distribution, large population sizes and high dispersal capacities. However, gene flow can be influenced by ecological (e.g. homing behaviour) and physical (e.g. present-day ocean currents, past changes in sea temperature and levels) factors. In this regard, Atlantic bigeye tuna shows an interesting genetic structuring pattern with two highly divergent mitochondrial clades (Clades I and II), which are assumed to have been originated during the last Pleistocene glacial maxima. We assess genetic structure patterns of Atlantic bigeye tuna at the nuclear level, and compare them with mitochondrial evidence. Results We examined allele size variation of nine microsatellite loci in 380 individuals from the Gulf of Guinea, Canary, Azores, Canada, Indian Ocean, and Pacific Ocean. To investigate temporal stability of genetic structure, three Atlantic Ocean sites were re-sampled a second year. Hierarchical AMOVA tests, RST pairwise comparisons, isolation by distance (Mantel) tests, Bayesian clustering analyses, and coalescence-based migration rate inferences supported unrestricted gene flow within the Atlantic Ocean at the nuclear level, and therefore interbreeding between individuals belonging to both mitochondrial clades. Moreover, departures from HWE in several loci were inferred for the samples of Guinea, and attributed to a Wahlund effect supporting the role of this region as a spawning and nursery area. Our microsatellite data supported a single worldwide panmictic unit for bigeye tunas. Despite the strong Agulhas Current, immigration rates seem to be higher from the Atlantic Ocean into the Indo-Pacific Ocean, but the actual number of individuals moving per generation is relatively low compared to the large population sizes inhabiting each ocean basin. Conclusion Lack of congruence between mt and nuclear evidences, which is also found in other

  11. Form and function of the bulbus arteriosus in yellowfin tuna (Thunnus albacares): dynamic properties.

    PubMed

    Braun, Marvin H; Brill, Richard W; Gosline, John M; Jones, David R

    2003-10-01

    The bulbus arteriosus of the teleost heart possesses a static inflation curve that is r-shaped over the in vivo pressure range. To examine the possible significance of this in living animals, we recorded arterial blood pressure from anaesthetized yellowfin tuna and utilized a video dimensional analyser to simultaneously record changes in bulbar diameter. By plotting the changes in pressure against the changes in diameter, it was possible to create dynamic pressure-diameter (P-D) loops as well as calculate the instantaneous volume changes within the bulbus. The dynamic P-D loops showed the same features exhibited by static inflation. When nearly empty, a small stroke volume caused a large increase in blood pressure, while around systolic pressure large changes in volume resulted in small changes in pressure. We conclude that these features allow the bulbus to maintain ventral aortic flows and pressures over a large range of volumes. PMID:12939365

  12. 50 CFR 300.211 - Definitions.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... migratory species (or HMS) means any of the following species: Common name Scientific name Albacore Thunnus alalunga. Pacific bluefin tuna Thunnus orientalis. Southern bluefin tuna Thunnus maccoyii. Bigeye tuna Thunnus obesus. Skipjack tuna Katsuwonus pelamis. Yellowfin tuna Thunnus albacares. Little tuna...

  13. Spatially explicit estimates of stock size, structure and biomass of North Atlantic albacore Tuna (Thunnus alalunga)

    NASA Astrophysics Data System (ADS)

    Lehodey, P.; Senina, I.; Dragon, A.-C.; Arrizabalaga, H.

    2014-04-01

    The development of the ecosystem approach and models for the management of ocean marine resources requires easy access to standard validated datasets of historical catch data for the main exploited species. They are used to measure the impact of biomass removal by fisheries and to evaluate the models skills, while the use of standard dataset facilitates models inter-comparison. Unlike standard stock assessment models, new state-of-the-art ecosystem models require geo-referenced fishing data with highest possible spatial resolution. This study presents an application to the north Atlantic albacore tuna stock with a careful definition and validation of a spatially explicit fishing dataset prepared from publically available sources (ICCAT) for its use in a spatial ecosystem and population dynamics model (SEAPODYM) to provide the first spatially explicit estimate of albacore density in the North Atlantic by life stage. Density distributions are provided (http://doi.pangaea.de/10.1594/PANGAEA.831499) together with the fishing data used for these estimates http://doi.pangaea.de/10.1594/PANGAEA.830797, http://doi.pangaea.de/10.15 1594/PANGAEA.828168, http://doi.pangaea.de/10.1594/PANGAEA.828170, and http://doi.pangaea.de/10.1594/PANGAEA.828171 (see section Source Data References).

  14. Spatially explicit estimates of stock size, structure and biomass of North Atlantic albacore tuna (Thunnus alalunga)

    NASA Astrophysics Data System (ADS)

    Lehodey, P.; Senina, I.; Dragon, A.-C.; Arrizabalaga, H.

    2014-09-01

    The development of the ecosystem approach and models for the management of ocean marine resources requires easy access to standard validated data sets of historical catch data for the main exploited species. They are used to measure the impact of biomass removal by fisheries and to evaluate the models outputs, while the use of a standard data set facilitates models inter-comparison. Unlike standard stock assessment models, new state-of-the-art ecosystem models require geo-referenced fishing data with the highest possible spatial resolution. This study presents an application to the North Atlantic albacore tuna stock with a careful definition and validation of a spatially explicit fishing data set prepared from publicly available sources (ICCAT) for its use in a spatial ecosystem and population dynamics model (SEAPODYM) to provide the first spatially explicit estimate of albacore density in the North Atlantic by life stage. Density distributions together with the fishing data used for the estimates are provided at http://doi.pangaea.de/ (see section Source Data References) (doi:10.1594/PANGAEA.828115; doi:10.1594/PANGAEA.828226; doi:10.1594/PANGAEA.828227; doi:10.1594/PANGAEA.828228; doi:10.1594/PANGAEA.828229; doi:10.1594/PANGAEA.828230; doi:10.1594/PANGAEA.828231; doi:10.1594/PANGAEA.828232; doi:10.1594/PANGAEA.828232; doi:10.1594/PANGAEA.828233; Effects of brine concentration on lipid oxidation and fatty acids profile of hot smoked tuna ( Thunnus albacares ) stored at refrigerated temperature.

    PubMed

    Guizani, Nejib; Rahman, Mohammad Shafiur; Al-Ruzeiqi, Mohamed Hamad; Al-Sabahi, Jamal Nasser; Sureshchandran, Sithara

    2014-03-01

    This work evaluated the lipid oxidation and the changes in fatty acids in hot-smoked tuna (Thunnus albacares) as a function of brine concentration. Fresh, commercially harvested tuna fish samples were purchased from a local supermarket. The fish were first immersed for 30 min in a brine solution at 5, 10, or 15% sodium chloride concentration and were then smoked at 50 °C for 3 h followed by 1 h at 60 °C and 3 h at 105 °C. The fish were then dried for 17 h, cooled and stored at 4 °C. Oxidative rancidity was measured by the peroxide value (PV), and thiobarbituric acid number (TBA) and fatty acids profile by GC-MS. Oxidative rancidity increased with storage time. The PV and TBARS values were more pronounced for samples immersed in 10% brine solution during the first 27 days of storage, whereas the lowest increase was observed for samples treated with 15% salt. Fatty acid concentration exhibited changes after smoking, and this was varied with salt concentration. The palmitic acid and stearic acid, the two main saturated fatty acids in tuna, increased after smoking at all brine concentration, whereas the contents of oleic acid, eicosapentaenoic acid and docosahexaenoic acid decreased. In conclusion, 15% NaCl-treated tuna gave smoked product with less lipid oxidation and a fatty acid profile comparable to that for 5 and 10% NaCl-treated samples. PMID:24587535

  15. Draft Genome Sequences of Histamine-Producing Photobacterium kishitanii and Photobacterium angustum, Isolated from Albacore (Thunnus alalunga) and Yellowfin (Thunnus albacares) Tuna.

    PubMed

    Bjornsdottir-Butler, Kristin; McCarthy, Susan A; Dunlap, Paul V; Timme, Ruth E; Benner, Ronald A

    2015-01-01

    Histamine-producing bacteria are responsible for scombrotoxin (histamine) fish poisoning, a leading cause of fish poisoning in the United States. We report here the draft genome sequences of four histamine-producing (HP) Photobacterium kishitanii strains and nine HP Photobacterium angustum strains isolated from tuna. PMID:25931609

  16. Draft Genome Sequences of Histamine-Producing Photobacterium kishitanii and Photobacterium angustum, Isolated from Albacore (Thunnus alalunga) and Yellowfin (Thunnus albacares) Tuna

    PubMed Central

    McCarthy, Susan A.; Dunlap, Paul V.; Timme, Ruth E.; Benner, Ronald A.

    2015-01-01

    Histamine-producing bacteria are responsible for scombrotoxin (histamine) fish poisoning, a leading cause of fish poisoning in the United States. We report here the draft genome sequences of four histamine-producing (HP) Photobacterium kishitanii strains and nine HP Photobacterium angustum strains isolated from tuna. PMID:25931609

  17. Comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry for the identification of organobrominated compounds in bluefin tuna.

    PubMed

    Pena-Abaurrea, Miren; Covaci, Adrian; Ramos, Lourdes

    2011-09-28

    This study evaluates comprehensive two-dimensional gas chromatography (GC×GC) coupled to time-of-flight mass spectrometry (GC×GC-ToF MS) for the simultaneous analysis of several classes of organobromines (OBs), including polybrominated diphenyl ethers (PBDEs), polybrominated biphenyls (PBBs), methoxylated PBDEs (MeO-PBDEs), several halogenated naturally produced compounds (HNPs) and eight novel brominated flame retardants (NBFRs), polybrominated hexahydroxanthene derivates (PBHDs), 2,4,6-tribromoanisole and a mixed halogenated compound (MHC-1), in bluefin tuna muscles. The proposed methodology maximised separation of both within and among OB families, and among these and other halogenated micropollutants detected in these samples and co-extracted matrix components. Special attention has been paid to solve co-elution problems observed during the analysis of OBs with one-dimensional GC-based techniques. Satisfactory separation among several relevant PBDEs and MeO-PBDEs has been obtained allowing their unambiguous determination in a single run. Additional studies were conducted to identify selected NBFRs and HNPs. 2,4-Dibromoanisole, a dibromophenol isomer and hexabromobenzene were identified in the investigated samples. Several new tri- and tetra-BHD derivates were also identified, indicating that these compounds could apparently exist as structured families in nature. In addition, a tetrabrominated diMeO-biphenyl and two tetrabrominated diMeO-BDEs were also tentatively identified. PMID:21872866

  18. Trophic Ecology of Atlantic Bluefin Tuna (Thunnusthynnus) Larvae from the Gulf of Mexico and NW Mediterranean Spawning Grounds: A Comparative Stable Isotope Study

    PubMed Central

    Malca, Estrella; Quintanilla, José María; Muhling, Barbara A.; Alemany, Francisco; Privoznik, Sarah L.; Shiroza, Akihiro; Lamkin, John T.; García, Alberto

    2015-01-01

    The present study uses stable isotopes of nitrogen and carbon (δ15Nandδ13C) as trophic indicators for Atlantic bluefin tuna larvae (BFT) (6–10 mm standard length) in the highly contrasting environmental conditions of the Gulf of Mexico (GOM) and the Balearic Sea (MED). These regions are differentiated by their temperature regime and relative productivity, with the GOM being significantly warmer and more productive. MED BFT larvae showed the highest δ15N signatures, implying an elevated trophic position above the underlying microzooplankton baseline. Ontogenetic dietary shifts were observed in the BFT larvae from the GOM and MED which indicates early life trophodynamics differences between these spawning habitats. Significant trophic differences between the GOM and MED larvae were observed in relation to δ15N signatures in favour of the MED larvae, which may have important implications in their growth during their early life stages.These low δ15N levels in the zooplankton from the GOM may be an indication of a shifting isotopic baseline in pelagic food webs due to diatrophic inputs by cyanobacteria. Lack of enrichment for δ15N in BFT larvae compared to zooplankton implies an alternative grazing pathway from the traditional food chain of phytoplankton—zooplankton—larval fish. Results provide insight for a comparative characterization of the trophic pathways variability of the two main spawning grounds for BFT larvae. PMID:26225849

  19. 76 FR 2313 - Atlantic Highly Migratory Species; Bluefin Tuna Bycatch Reduction in the Gulf of Mexico Pelagic...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-13

    ... published in the Federal Register (64 FR 29090) final regulations, effective July 1, 1999, implementing the... published in the Federal Register (71 FR 58058) final regulations, effective November 1, 2006, implementing... Tuna as Threatened or Endangered under the Endangered Species Act on Sept. 21, 2010 (75 FR 57431)....

  1. Skin lesions on yellowfin tuna Thunnus albacares from Gulf of Mexico outer continental shelf: Morphological, molecular, and histological diagnosis of infection by a capsalid monogenoid.

    PubMed

    Bullard, Stephen A; Womble, Matthew R; Maynard, Margaret K; Orélis-Ribeiro, Raphael; Arias, Cova R

    2015-12-01

    We characterize lesion-associated capsaline infections on yellowfin tuna, Thunnus albacares, in the Gulf of Mexico by comparing our specimens with published descriptions and museum specimens ascribed to Capsala biparasiticum and its synonyms: vouchers of C. biparasiticum from parasitic copepods; the holotype of Capsala neothunni; and vouchers of Capsala abidjani. Those from parasitic copepods differed by having a small, rounded body, large anterior attachment organs, closely spaced dorsomarginal body sclerites, small testes, and a short and wide testicular field. No morphometric feature in the holotype of C. neothunni ranged outside of that reported for the newly-collected specimens, indicating conspecificity of our specimens. The specimens of C. abidjani differed by having a large anterior attachment organ, few and dendritic testes, and a short, wide testicular field. Large subunit ribosomal DNA (28S) sequences grouped our specimens and Capsala sp. as sister taxa and indicated a phylogenetic affinity of Nasicola klawei. The haptoral attachment site comprised a crater-like depression surrounded by a blackish-colored halo of extensively rugose skin, with abundant pockmarked-like, irregularly-shaped oblong or semi-circular epidermal pits surrounding these attachment sites. Histology confirmed extensive folding of epidermis and underlying stratum laxum, likely epidermal hyperplasia, foci of weak cell-to-cell adhesions among apical malpighian cells as well as that between stratum germinativum and stratum laxum, myriad goblet cells in epidermis, rodlet cells in apical layer of epidermis, and lymphocytic infiltrates and melanin in dermis. The present study comprises (i) the first published report of this parasite from yellowfin tuna captured in the Gulf of Mexico-NW Atlantic Ocean Basin, (ii) confirmation of its infection on the skin (rather than on a parasitic copepod), (iii) the first molecular data for this capsaline, and (iv) the first observations of

  2. Effects of on-board and dockside handling on the formation of biogenic amines in mahimahi (Coryphaena hippurus), skipjack tuna (Katsuwonus pelamis), and yellowfin tuna (Thunnus albacares).

    PubMed

    Staruszkiewicz, Walter F; Barnett, James D; Rogers, Patricia L; Benner, Ronald A; Wong, Lynn L; Cook, John

    2004-01-01

    Consumer illnesses by scombroid poisonings have been a continuing problem for many years. The intoxications follow the ingestion of fish such as tuna and mahimahi that have undergone bacterial decomposition, leading to the formation of biogenic amines. Research studies have concluded that histamine is one of the indicators of scombrotoxic fish and that other amines, such as cadaverine, could be involved in the illnesses. Guidance for the handling of fish on board fishing vessels to prevent the production of scombrotoxic fish has been limited by a lack of data addressing changes that occur in fish from the water to delivery at dockside. In this study, the changes in selected biogenic amines were determined in mahimahi and tuna, which were captured and held in seawater at 25 to 35 degrees C for incubation times up to 18 h. The fillets from the treated fish were sectioned by transverse cuts and analyzed for histamine, cadaverine, and putrescine. Results showed that at 26 degrees C, more than 12 h of incubation were required before a histamine concentration of 50 ppm was reached in mahimahi. At 35 degrees C, 50 ppm histamine formed within 9 h. Similar results were found for skipjack and yellowfin tuna. Histamine concentrations exceeded 500 ppm within an additional 3 h of incubation in mahimahi. At both temperatures, an increase in the concentration of cadaverine preceded an increase in histamine levels. Changes in putrescine concentrations in the fish were less pronounced. The study also demonstrated that histidine decarboxylase activity was retained in some frozen samples of fish and could result in further increases in histamine on thawing. PMID:14717363

  3. Physicochemical and sensory characterization of refined and deodorized tuna (Thunnus albacares) by-product oil obtained by enzymatic hydrolysis.

    PubMed

    de Oliveira, Dayse A S B; Minozzo, Marcelo G; Licodiedoff, Silvana; Waszczynskyj, Nina

    2016-09-15

    In this study, the effects of chemical refining and deodorization on fatty acid profiles and physicochemical and sensory characteristics of the tuna by-product oil obtained by enzymatic hydrolysis were evaluated. Enzymatic extraction was conducted for 120 min at 60 °C and pH 6.5 using Alcalase at an enzyme-substrate ratio of 1:200 w/w. The chemical refining of crude oil consisted of degumming, neutralization, washing, drying, bleaching, and deodorization; deodorization was conducted at different temperatures and processing times. Although chemical refining was successful, temperature and chemical reagents favored the removal of polyunsaturated fatty acids (PUFA) from the oil. Aroma attributes of fishy odor, frying odor, and rancid odor predominantly contributed to the sensory evaluation of the product. Deodorization conditions of 160 °C for 1h and 200 °C for 1h were recommended for the tuna by-product oil, which is rich in PUFA. PMID:27080896

  4. Evidence of discrete yellowfin tuna (Thunnus albacares) populations demands rethink of management for this globally important resource

    NASA Astrophysics Data System (ADS)

    Grewe, P. M.; Feutry, P.; Hill, P. L.; Gunasekera, R. M.; Schaefer, K. M.; Itano, D. G.; Fuller, D. W.; Foster, S. D.; Davies, C. R.

    2015-11-01

    Tropical tuna fisheries are central to food security and economic development of many regions of the world. Contemporary population assessment and management generally assume these fisheries exploit a single mixed spawning population, within ocean basins. To date population genetics has lacked the required power to conclusively test this assumption. Here we demonstrate heterogeneous population structure among yellowfin tuna sampled at three locations across the Pacific Ocean (western, central, and eastern) via analysis of double digest restriction-site associated DNA using Next Generation Sequencing technology. The differences among locations are such that individuals sampled from one of the three regions examined can be assigned with close to 100% accuracy demonstrating the power of this approach for providing practical markers for fishery independent verification of catch provenance in a way not achieved by previous techniques. Given these results, an extended pan-tropical survey of yellowfin tuna using this approach will not only help combat the largest threat to sustainable fisheries (i.e. illegal, unreported, and unregulated fishing) but will also provide a basis to transform current monitoring, assessment, and management approaches for this globally significant species.

  5. Evidence of discrete yellowfin tuna (Thunnus albacares) populations demands rethink of management for this globally important resource

    PubMed Central

    Grewe, P. M.; Feutry, P.; Hill, P. L.; Gunasekera, R. M.; Schaefer, K. M.; Itano, D. G.; Fuller, D. W.; Foster, S. D.; Davies, C. R.

    2015-01-01

    Tropical tuna fisheries are central to food security and economic development of many regions of the world. Contemporary population assessment and management generally assume these fisheries exploit a single mixed spawning population, within ocean basins. To date population genetics has lacked the required power to conclusively test this assumption. Here we demonstrate heterogeneous population structure among yellowfin tuna sampled at three locations across the Pacific Ocean (western, central, and eastern) via analysis of double digest restriction-site associated DNA using Next Generation Sequencing technology. The differences among locations are such that individuals sampled from one of the three regions examined can be assigned with close to 100% accuracy demonstrating the power of this approach for providing practical markers for fishery independent verification of catch provenance in a way not achieved by previous techniques. Given these results, an extended pan-tropical survey of yellowfin tuna using this approach will not only help combat the largest threat to sustainable fisheries (i.e. illegal, unreported, and unregulated fishing) but will also provide a basis to transform current monitoring, assessment, and management approaches for this globally significant species. PMID:26593698

  6. Evidence of discrete yellowfin tuna (Thunnus albacares) populations demands rethink of management for this globally important resource.

    PubMed

    Grewe, P M; Feutry, P; Hill, P L; Gunasekera, R M; Schaefer, K M; Itano, D G; Fuller, D W; Foster, S D; Davies, C R

    2015-01-01

    Tropical tuna fisheries are central to food security and economic development of many regions of the world. Contemporary population assessment and management generally assume these fisheries exploit a single mixed spawning population, within ocean basins. To date population genetics has lacked the required power to conclusively test this assumption. Here we demonstrate heterogeneous population structure among yellowfin tuna sampled at three locations across the Pacific Ocean (western, central, and eastern) via analysis of double digest restriction-site associated DNA using Next Generation Sequencing technology. The differences among locations are such that individuals sampled from one of the three regions examined can be assigned with close to 100% accuracy demonstrating the power of this approach for providing practical markers for fishery independent verification of catch provenance in a way not achieved by previous techniques. Given these results, an extended pan-tropical survey of yellowfin tuna using this approach will not only help combat the largest threat to sustainable fisheries (i.e. illegal, unreported, and unregulated fishing) but will also provide a basis to transform current monitoring, assessment, and management approaches for this globally significant species. PMID:26593698

  7. New Nuclear SNP Markers Unravel the Genetic Structure and Effective Population Size of Albacore Tuna (Thunnus alalunga).

    PubMed

    Laconcha, Urtzi; Iriondo, Mikel; Arrizabalaga, Haritz; Manzano, Carmen; Markaide, Pablo; Montes, Iratxe; Zarraonaindia, Iratxe; Velado, Igor; Bilbao, Eider; Goñi, Nicolas; Santiago, Josu; Domingo, Andrés; Karakulak, Saadet; Oray, Işık; Estonba, Andone

    2015-01-01

    In the present study we have investigated the population genetic structure of albacore (Thunnus alalunga, Bonnaterre 1788) and assessed the loss of genetic diversity, likely due to overfishing, of albacore population in the North Atlantic Ocean. For this purpose, 1,331 individuals from 26 worldwide locations were analyzed by genotyping 75 novel nuclear SNPs. Our results indicated the existence of four genetically homogeneous populations delimited within the Mediterranean Sea, the Atlantic Ocean, the Indian Ocean and the Pacific Ocean. Current definition of stocks allows the sustainable management of albacore since no stock includes more than one genetic entity. In addition, short- and long-term effective population sizes were estimated for the North Atlantic Ocean albacore population, and results showed no historical decline for this population. Therefore, the genetic diversity and, consequently, the adaptive potential of this population have not been significantly affected by overfishing. PMID:26090851

  8. New Nuclear SNP Markers Unravel the Genetic Structure and Effective Population Size of Albacore Tuna (Thunnus alalunga)

    PubMed Central

    Laconcha, Urtzi; Iriondo, Mikel; Arrizabalaga, Haritz; Manzano, Carmen; Markaide, Pablo; Montes, Iratxe; Zarraonaindia, Iratxe; Velado, Igor; Bilbao, Eider; Goñi, Nicolas; Santiago, Josu; Domingo, Andrés; Karakulak, Saadet; Oray, Işık; Estonba, Andone

    2015-01-01

    In the present study we have investigated the population genetic structure of albacore (Thunnus alalunga, Bonnaterre 1788) and assessed the loss of genetic diversity, likely due to overfishing, of albacore population in the North Atlantic Ocean. For this purpose, 1,331 individuals from 26 worldwide locations were analyzed by genotyping 75 novel nuclear SNPs. Our results indicated the existence of four genetically homogeneous populations delimited within the Mediterranean Sea, the Atlantic Ocean, the Indian Ocean and the Pacific Ocean. Current definition of stocks allows the sustainable management of albacore since no stock includes more than one genetic entity. In addition, short- and long-term effective population sizes were estimated for the North Atlantic Ocean albacore population, and results showed no historical decline for this population. Therefore, the genetic diversity and, consequently, the adaptive potential of this population have not been significantly affected by overfishing. PMID:26090851

  9. Evaluation of FAD-associated purse seine fishery reduction strategies for bigeye tuna ( Thunnus obesus) in the Indian Ocean

    NASA Astrophysics Data System (ADS)

    Tong, Yuhe; Chen, Xinjun; Xu, Liuxiong; Chen, Yong

    2013-07-01

    In the Indian Ocean, bigeye tuna supports one of the most important fisheries in the world. This fishery mainly consists of two components: longline and purse seine fisheries. Evidence of overfishing and stock depletion of bigeye tuna calls for an evaluation of alternative management strategies. Using an age-structured operating model, parameterized with the results derived in a recent stock assessment, we evaluated the effectiveness of applying constant fishing mortality (CF) and quasi-constant fishing mortality (QCF) strategies to reduce fishing effort of purse seining with fish aggregating devices (FADs) at different rates. Three different levels of productivity accounted for the uncertainty in our understanding of stock productivity. The study shows that the results of CF and QCF are similar. Average SSB and catch during simulation years would be higher if fishing mortality of FAD-associated purse seining was reduced rapidly. The banning or rapid reduction of purse seining with FAD resulted in a mean catch, and catch in the last simulation year, higher than that of the base case in which no change was made to the purse seine fishery. This could be caused by growth overfishing by purse seine fisheries with FADs according to the per-recruit analysis. These differences would be more obvious when stock productivity was low. Transferring efforts of FAD-associated purse seining to longline fisheries is also not feasible. Our study suggests that changes are necessary to improve the performance of the current management strategy.

  10. The Distribution of Bigeye Tuna, Thunnus Obesus, and Three-Dimensional Thermal Structures Estimated from Satellite Altimeter

    NASA Astrophysics Data System (ADS)

    Takano, A.; Yamazaki, H.

    2006-07-01

    In order to improve the accuracy of estimation of fish distribution, one needs to know real-time oceanographic conditions where fish concentrate. In this contribution, we propose an empirical approach to estimate three-dimensional thermal structure in near real time using satellite altimeter data. Making use of a two-layer system model (Goni et al, 1996), an empirical regression model for three-dimensional thermal structure is derived combining absolute dynamic topography (ADT) by AVISO, in-situ data of temperature and salinity measured by Argo profiling floats, and monthly mean objective analysis data of temperature and salinity. We have applied the proposed technique to estimate three-dimensional thermal structure of the western part of the North Pacific subtropical gyre. We show a good agreement between the model result and observed temperature profiles taken from XBT. We also demonstrate that the location of bigeye tuna (Tunnus obesus) fishing ground appears where deep thermocline shallows. This procedure makes it possible to improve the accuracy of estimation for the distribution of bigeye tuna.

  11. Antihypertensive effect of angiotensin i converting enzyme-inhibitory peptide from hydrolysates of Bigeye tuna dark muscle, Thunnus obesus.

    PubMed

    Qian, Zhong-Ji; Je, Jae-Young; Kim, Se-Kwon

    2007-10-17

    Angiotensin I converting enzyme (ACE) inhibitory peptide was isolated from tuna dark muscle hydrolysate prepared by alcalase, neutrase, pepsin, papain, alpha-chymotrypsin, and trypsin, respectively. Among hydrolysates, the pepsin-derived hydrolysate exhibited the highest ACE I inhibitory activity versus those of other enzyme hydrolysates. The structure of the peptide was identified to be Trp-Pro-Glu-Ala-Ala-Glu-Leu-Met-Met-Glu-Val-Asp-Pro (molecular weight 1581 Da) by time of flight mass spectrometry/mass spectrometry analysis, and the IC 50 value of the peptide was 21.6 microM. The Lineweaver-Burk plots revealed that the peptide acts as a noncompetitive inhibitor, and the inhibitor constant ( K i) was calculated as 26.6 microM using the secondary plots. The peptide had an antihypertensive effect according to the time-course measurement after oral administration to spontaneously hypertensive rats. Maximal reduction was detected 3 h after oral administration at a dose of 10 mg/kg of body weight. These results suggest that the peptide derived from tuna dark muscle would be a beneficial ingredient for functional food or pharmaceuticals against hypertension and its related diseases. PMID:17894458

  12. Purification and antioxidant properties of bigeye tuna (Thunnus obesus) dark muscle peptide on free radical-mediated oxidative systems.

    PubMed

    Je, Jae-Young; Qian, Zhong-Ji; Lee, Sang-Hoon; Byun, Hee-Guk; Kim, Se-Kwon

    2008-12-01

    To produce bioactive peptides from by-products of fish processing, bigeye tuna dark muscle was hydrolyzed using various enzymes (alcalase, alpha-chymotrypsin, neutrase, papain, pepsin, and trypsin), and the hydrolysates were evaluated for antioxidant activity. Considering the results of degree of hydrolysis and antioxidant activities, peptic hydrolysate was used for further studies to identify a potent antioxidant peptide. Antioxidant peptide was purified using consecutive chromatographic methods and was identified as being H-Leu-Asn-Leu-Pro-Thr-Ala-Val-Tyr-Met-Val-Thr-OH (MW 1,222 Da) by quantitative time-of-flight electrospray ionization mass spectrometry. Purified antioxidant peptide from bigeye tuna dark muscle (APTDM) was investigated for its antioxidant activities using both free radical scavenging effects and polyunsaturated fatty acid (PUFA) peroxidation inhibitory activity. The results showed that APTDM effectively quenched with low 50% inhibitory concentration values compared to vitamin C as a positive control against four different free radicals: 1,1-diphenyl-2-picrylhydrazyl, hydroxyl, superoxide, and alkyl radical. APTDM also inhibited PUFA peroxidation in a linoleic acid emulsion system, and the activity was similar to that of alpha-tocopherol. We further investigated its antioxidant activities on cellular systems, and the results showed that APTDM significantly scavenged cellular radicals and enhanced the viability of tert-butyl hydroperoxide-induced cytotoxicity. These results indicate that APTDM or a peptide fraction containing APTDM would be a beneficial ingredient for functional food and/or pharmaceuticals. PMID:19053853

  13. Maturity Ogives for South Pacific Albacore Tuna (Thunnus alalunga) That Account for Spatial and Seasonal Variation in the Distributions of Mature and Immature Fish

    PubMed Central

    Farley, Jessica H.; Hoyle, Simon D.; Eveson, J. Paige; Williams, Ashley J.; Davies, Campbell R.; Nicol, Simon J.

    2014-01-01

    Length and age at maturity are important life history parameters for estimating spawning stock biomass and reproductive potential of fish stocks. Bias in estimates of size and age at maturity can arise when disparate distributions of mature and immature fish within a population are not accounted for in the analysis. Here we investigate the spatial and temporal variability in observed size and age at maturity of female albacore tuna, Thunnus alalunga, using samples collected across the South Pacific. Maturity status was identified using consistent histological criteria that were precise enough to allow for mature but regenerating females to be distinguished from immature females during the non-spawning season, permitting year-round sampling for maturity estimation in albacore. Using generalised linear mixed models, we found that the proportion of mature females at length varied significantly with latitude and time of year. Specifically, females at northern latitudes (∼10–20°S, where spawning occurs) were mature at significantly smaller lengths and ages than females at southern latitudes (∼20–40°S), particularly during the spawning season (October–March). This variation was due to different geographic distributions of mature and immature fish during the year. We present a method for estimating an unbiased maturity ogive that takes into account the latitudinal variation in proportion mature at length during a given season (spawning or non-spawning). Applying this method to albacore samples from the western region of the South Pacific gave a predicted length at 50% mature of ∼87 cm fork length (4.5 years). PMID:24416153

  14. Maturity ogives for South Pacific albacore tuna (Thunnus alalunga) that account for spatial and seasonal variation in the distributions of mature and immature fish.

    PubMed

    Farley, Jessica H; Hoyle, Simon D; Eveson, J Paige; Williams, Ashley J; Davies, Campbell R; Nicol, Simon J

    2014-01-01

    Length and age at maturity are important life history parameters for estimating spawning stock biomass and reproductive potential of fish stocks. Bias in estimates of size and age at maturity can arise when disparate distributions of mature and immature fish within a population are not accounted for in the analysis. Here we investigate the spatial and temporal variability in observed size and age at maturity of female albacore tuna, Thunnus alalunga, using samples collected across the South Pacific. Maturity status was identified using consistent histological criteria that were precise enough to allow for mature but regenerating females to be distinguished from immature females during the non-spawning season, permitting year-round sampling for maturity estimation in albacore. Using generalised linear mixed models, we found that the proportion of mature females at length varied significantly with latitude and time of year. Specifically, females at northern latitudes (∼10-20°S, where spawning occurs) were mature at significantly smaller lengths and ages than females at southern latitudes (∼20-40°S), particularly during the spawning season (October-March). This variation was due to different geographic distributions of mature and immature fish during the year. We present a method for estimating an unbiased maturity ogive that takes into account the latitudinal variation in proportion mature at length during a given season (spawning or non-spawning). Applying this method to albacore samples from the western region of the South Pacific gave a predicted length at 50% mature of ∼87 cm fork length (4.5 years). PMID:24416153

  15. 210Po Activity and concentrations of selected trace elements (As, Cd, Cu, Hg, Pb, Zn) in the muscle tissue of tunas Thunnus albacares and Katsuwonus pelamis from the Eastern Pacific Ocean.

    PubMed

    Ruelas-Inzunza, Jorge; Soto-Jiménez, Martín Federico; Ruiz-Fernández, Ana Carolina; Bojórquez-Leyva, Humberto; Pérez-Bernal, Hascibe; Páez-Osuna, Federico

    2012-12-01

    Daily mineral intake (DMI) of Cu and Zn, percentage weekly intake (PWI) of As, Cd, Hg, Pb, and doses of (210)Po were estimated by using their elemental concentration in muscle of two tuna species and the average tuna consumption in Mexico. Skipjack tuna Katsuwonus pelamis had significantly (p < 0.05) higher levels of As (1.38 μg g(-1) dw) and Cu (1.85 μg g(-1) dw) than yellowfin tuna Thunnus albacares, whereas Pb concentrations (0.18 μg g(-1) dw) were significantly (p < 0.05) higher in T. albacares. The sequence of elemental concentrations in both species was Zn > Cu > As > Hg > Pb > Cd. In T. albacares, concentrations of Cd and Pb in muscle tissue were positively correlated (p < 0.05) with weight of specimens, while Cu was negatively correlated. DMI values were below 10 %. PWI figures (<2 %) are not potentially harmful to human health. (210)Po concentration in T. albacares and K. pelamis accounts for 13.5 to 89.7 % of the median individual annual dose (7.1 μSv) from consumption of marine fish and shellfish for the world population. PMID:22684512

  16. The Real maccoyii: Identifying Tuna Sushi with DNA Barcodes – Contrasting Characteristic Attributes and Genetic Distances

    PubMed Central

    Lowenstein, Jacob H.; Amato, George; Kolokotronis, Sergios-Orestis

    2009-01-01

    Background The use of DNA barcodes for the identification of described species is one of the least controversial and most promising applications of barcoding. There is no consensus, however, as to what constitutes an appropriate identification standard and most barcoding efforts simply attempt to pair a query sequence with reference sequences and deem identification successful if it falls within the bounds of some pre-established cutoffs using genetic distance. Since the Renaissance, however, most biological classification schemes have relied on the use of diagnostic characters to identify and place species. Methodology/Principal Findings Here we developed a cytochrome c oxidase subunit I character-based key for the identification of all tuna species of the genus Thunnus, and compared its performance with distance-based measures for identification of 68 samples of tuna sushi purchased from 31 restaurants in Manhattan (New York City) and Denver, Colorado. Both the character-based key and GenBank BLAST successfully identified 100% of the tuna samples, while the Barcode of Life Database (BOLD) as well as genetic distance thresholds, and neighbor-joining phylogenetic tree building performed poorly in terms of species identification. A piece of tuna sushi has the potential to be an endangered species, a fraud, or a health hazard. All three of these cases were uncovered in this study. Nineteen restaurant establishments were unable to clarify or misrepresented what species they sold. Five out of nine samples sold as a variant of “white tuna” were not albacore (T. alalunga), but escolar (Lepidocybium flavorunneum), a gempylid species banned for sale in Italy and Japan due to health concerns. Nineteen samples were northern bluefin tuna (T. thynnus) or the critically endangered southern bluefin tuna (T. maccoyii), though nine restaurants that sold these species did not state these species on their menus. Conclusions/Significance The Convention on International Trade

  17. Accounting for Age Uncertainty in Growth Modeling, the Case Study of Yellowfin Tuna (Thunnus albacares) of the Indian Ocean

    PubMed Central

    Dortel, Emmanuelle; Massiot-Granier, Félix; Rivot, Etienne; Million, Julien; Hallier, Jean-Pierre; Morize, Eric; Munaron, Jean-Marie; Bousquet, Nicolas; Chassot, Emmanuel

    2013-01-01

    Age estimates, typically determined by counting periodic growth increments in calcified structures of vertebrates, are the basis of population dynamics models used for managing exploited or threatened species. In fisheries research, the use of otolith growth rings as an indicator of fish age has increased considerably in recent decades. However, otolith readings include various sources of uncertainty. Current ageing methods, which converts an average count of rings into age, only provide periodic age estimates in which the range of uncertainty is fully ignored. In this study, we describe a hierarchical model for estimating individual ages from repeated otolith readings. The model was developed within a Bayesian framework to explicitly represent the sources of uncertainty associated with age estimation, to allow for individual variations and to include knowledge on parameters from expertise. The performance of the proposed model was examined through simulations, and then it was coupled to a two-stanza somatic growth model to evaluate the impact of the age estimation method on the age composition of commercial fisheries catches. We illustrate our approach using the saggital otoliths of yellowfin tuna of the Indian Ocean collected through large-scale mark-recapture experiments. The simulation performance suggested that the ageing error model was able to estimate the ageing biases and provide accurate age estimates, regardless of the age of the fish. Coupled with the growth model, this approach appeared suitable for modeling the growth of Indian Ocean yellowfin and is consistent with findings of previous studies. The simulations showed that the choice of the ageing method can strongly affect growth estimates with subsequent implications for age-structured data used as inputs for population models. Finally, our modeling approach revealed particularly useful to reflect uncertainty around age estimates into the process of growth estimation and it can be applied to any

  18. Accounting for age uncertainty in growth modeling, the case study of yellowfin tuna (Thunnus albacares) of the Indian Ocean.

    PubMed

    Dortel, Emmanuelle; Massiot-Granier, Félix; Rivot, Etienne; Million, Julien; Hallier, Jean-Pierre; Morize, Eric; Munaron, Jean-Marie; Bousquet, Nicolas; Chassot, Emmanuel

    2013-01-01

    Age estimates, typically determined by counting periodic growth increments in calcified structures of vertebrates, are the basis of population dynamics models used for managing exploited or threatened species. In fisheries research, the use of otolith growth rings as an indicator of fish age has increased considerably in recent decades. However, otolith readings include various sources of uncertainty. Current ageing methods, which converts an average count of rings into age, only provide periodic age estimates in which the range of uncertainty is fully ignored. In this study, we describe a hierarchical model for estimating individual ages from repeated otolith readings. The model was developed within a Bayesian framework to explicitly represent the sources of uncertainty associated with age estimation, to allow for individual variations and to include knowledge on parameters from expertise. The performance of the proposed model was examined through simulations, and then it was coupled to a two-stanza somatic growth model to evaluate the impact of the age estimation method on the age composition of commercial fisheries catches. We illustrate our approach using the sagittal otoliths of yellowfin tuna of the Indian Ocean collected through large-scale mark-recapture experiments. The simulation performance suggested that the ageing error model was able to estimate the ageing biases and provide accurate age estimates, regardless of the age of the fish. Coupled with the growth model, this approach appeared suitable for modeling the growth of Indian Ocean yellowfin and is consistent with findings of previous studies. The simulations showed that the choice of the ageing method can strongly affect growth estimates with subsequent implications for age-structured data used as inputs for population models. Finally, our modeling approach revealed particularly useful to reflect uncertainty around age estimates into the process of growth estimation and it can be applied to any

  19. Significant histamine formation in tuna (Thunnus albacares) at 2 degrees C--effect of vacuum- and modified atmosphere-packaging on psychrotolerant bacteria.

    PubMed

    Emborg, Jette; Laursen, Birgit Groth; Dalgaard, Paw

    2005-06-15

    Occurrence and importance of psychrotolerant histamine producing bacteria in chilled fresh tuna were demonstrated in the present study. The objective was to evaluate microbial formation of histamine and biogenic amines in chilled fresh tuna from the Indian Ocean and stored either vacuum-packed (VP) or modified atmosphere-packed (MAP). Firstly, biogenic amines and the dominating microbiota were determined in VP tuna involved in an outbreak of histamine fish poisoning in Denmark. Secondly, the microbiota of fresh MAP tuna was evaluated at the time of processing in Sri Lanka and chemical, microbial and sensory changes were evaluated during storage at 1-3 degrees C. To explain the results obtained with naturally contaminated tuna the effect of VP and MAP on biogenic amine formation by psychrotolerant bacteria was evaluated in challenge tests at 2 degrees C and 10 degrees C. The VP tuna that caused histamine fish poisoning had a histamine concentration of >7000 mg/kg and this high concentration was most likely produced by psychrotolerant Morganella morganii-like bacteria or by Photobacterium phosphoreum. Similar psychrotolerant M. morganii-like bacteria dominated the spoilage microbiota of fresh MAP tuna with 60% CO2/40% N2 and formed >5000 mg/kg of histamine after 24 days at 1.7 degrees C. These psychrotolerant bacteria were biochemically similar to M. morganii subsp. morganii and their 16S rDNA (1495 bp) showed >98% sequence similarity to the type strain of this species. Toxic concentrations of histamine were produced at 2.1 degrees C in inoculated VP tuna by both the psychrotolerant M. morganii-like bacteria (7400+/-1050 mg/kg) and P. phosphoreum (4250+/-2050 mg/kg). Interestingly, MAP with 40% CO2/60% O2, in challenge tests, had a strong inhibitory effect on growth and histamine formation by both the psychrotolerant M. morganii-like bacteria and P. phosphoreum. In agreement with this, no formation of histamine was found in naturally contaminated fresh MAP tuna with

  20. Global habitat preferences of commercially valuable tuna

    NASA Astrophysics Data System (ADS)

    Arrizabalaga, Haritz; Dufour, Florence; Kell, Laurence; Merino, Gorka; Ibaibarriaga, Leire; Chust, Guillem; Irigoien, Xabier; Santiago, Josu; Murua, Hilario; Fraile, Igaratza; Chifflet, Marina; Goikoetxea, Nerea; Sagarminaga, Yolanda; Aumont, Olivier; Bopp, Laurent; Herrera, Miguel; Marc Fromentin, Jean; Bonhomeau, Sylvain

    2015-03-01

    In spite of its pivotal role in future implementations of the Ecosystem Approach to Fisheries Management, current knowledge about tuna habitat preferences remains fragmented and heterogeneous, because it relies mainly on regional or local studies that have used a variety of approaches making them difficult to combine. Therefore in this study we analyse data from six tuna species in the Pacific, Atlantic and Indian Oceans in order to provide a global, comparative perspective of habitat preferences. These data are longline catch per unit effort from 1958 to 2007 for albacore, Atlantic bluefin, southern bluefin, bigeye, yellowfin and skipjack tunas. Both quotient analysis and Generalised Additive Models were used to determine habitat preference with respect to eight biotic and abiotic variables. Results confirmed that, compared to temperate tunas, tropical tunas prefer warm, anoxic, stratified waters. Atlantic and southern bluefin tuna prefer higher concentrations of chlorophyll than the rest. The two species also tolerate most extreme sea surface height anomalies and highest mixed layer depths. In general, Atlantic bluefin tuna tolerates the widest range of environmental conditions. An assessment of the most important variables determining fish habitat is also provided.

  1. 50 CFR Appendix A to Part 635 - Species Tables

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... isodon C. Pelagic Sharks Blue, Prionace glauca Oceanic whitetip, Carcharhinus longimanus Porbeagle, Lamna..., Carcharhinus porosus Whale, Rhincodon typus White, Carcharodon carcharias E. Smoothhound Sharks Smooth dogfish... Albacore tuna, Thunnus alalunga Bigeye tuna, Thunnus obesus Blue shark, Prionace glauca Bluefin...

  2. 50 CFR Appendix A to Part 635 - Species Tables

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... isodon C. Pelagic Sharks Blue, Prionace glauca Oceanic whitetip, Carcharhinus longimanus Porbeagle, Lamna..., Carcharhinus porosus Whale, Rhincodon typus White, Carcharodon carcharias E. Smoothhound Sharks Smooth dogfish... Albacore tuna, Thunnus alalunga Bigeye tuna, Thunnus obesus Blue shark, Prionace glauca Bluefin...

  3. Thawing of Frozen Dressed Tuna by Microwave Heating

    NASA Astrophysics Data System (ADS)

    Tanaka, Takeo; Nagasaki, Tasuku; Takahashi, Kenji

    Large sized frozen yellowfin tuna and southern bluefin tuna in dressed form (decapitated and gutted) were thawed by microwave (915 MHz) irradiation. Temperature rise of the tuna during thawing was measured. Quality of the tuna meat before and after thawing was compared with each other using objective quality index such as degree of discoloration (met-myoglobin ratio), freshness (K1 value) and taste cornponent (K2 value). Results are as follows : (1) Both frozen tunas were thawed fairly well within as short time as 30 min without any partial over heating. (2) No changes in met-myoglobin ratio, K1 and K2 values were observed in the cases of yellow fin tuna. Slight discoloration, however, occurred in southern bluefin tuna meat during microwave thawing. This problem has been left unsolved.

  4. [Correlation of fat content and dioxins, total mercury and methyl mercury levels in tuna].

    PubMed

    Kawakami, Hiroyuki; Amakura, Yoshiaki; Tsutsumi, Tomoaki; Sasaki, Kumiko; Iketsu, Ayumi; Inasaki, Mizue; Kubota, Emi; Toyoda, Masatake

    2010-01-01

    In this study, we analyzed the concentrations of mercury and dioxins in tuna with various fat contents (akami; the leaner meat, Chutoro; the belly area of the tuna along the side of the fish between the akami and the otoro. Otoro; the fattiest portion of the tuna) in wild and farmed bluefin tuna and farmed southern bluefin tuna. In the three kinds of tuna, average dioxins concentrations in Akami, chutoro and otoro were 1.7, 4.7 and 9.6 pg TEQ/g, respectively. The dioxins concentration in all three regions of tuna was in direct proportion to the fat content. In the farmed bluefin tuna, the dioxins concentration was almost the same as that of the wild tuna, but differed from that of the farmed southern bluefin tuna. Average total mercury concentration based on wet weight in akami was 0.42 µg/g, being higher than the values of 0.36 µg/g of chutoro and 0.31 µg/g of otoro, and in inverse proportion to the fat content. In all three regions, the total mercury concentration of the wild bluefin tuna was equal to that of the farmed tuna. The total mercury concentration in the latter was two to three times higher than that of the farmed southern bluefin tuna. If the Japanese intake is one fin of tuna (80 g) a day, the daily intake levels of dioxins and methyl mercury can be estimated as 0.48-37 pg TEQ/kg bw and 0.21-0.90 µg/kg bw, respectively. PMID:21071911

  5. A large outbreak of scombroid fish poisoning associated with eating yellowfin tuna (Thunnus albacares) at a military mass catering in Dakar, Senegal.

    PubMed

    Demoncheaux, J-P; Michel, R; Mazenot, C; Duflos, G; Iacini, C; de Laval, F; Delaval, F; Saware, E M; Renard, J-C

    2012-06-01

    On 26 November 2010, an outbreak of scombroid fish poisoning occurred in the French Armed Forces in Dakar, Senegal. This chemical intoxication, due to high histamine concentration in fish, is often mistaken for an allergic reaction. A case-control study was undertaken including the 71 cases and 78 randomly selected controls among lunch attendees. The usual symptoms for scombroid fish poisoning were observed in cases, i.e. flushing (85.9%), headache (83.1%), rapid/weak pulse (59.1%) and diarrhoea (47.9%). Symptoms occurred from within a few minutes to up to 3 h following the meal. Most patients quickly recovered with antihistamine and/or symptomatic treatment. Tuna was the only food item positively associated with illness (odds ratio 36.3, 95% confidence interval 6.3-210.0), with the risk of illness increasing with the quantity of fish consumed. No bacterial contamination was found in leftover food, but histamine concentration in tuna was found to be 4900 mg/kg, almost 50-fold higher than the concentration allowed by European regulations. This report is unique because of the large size of the case series - to our knowledge, the largest event of scombroid fish poisoning ever reported - and the chemical and bacteriological analyses results obtained on leftover food. PMID:21875451

  6. 50 CFR 600.15 - Other acronyms.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... management terms. (1) ABC—acceptable biological catch (2) ATCA-Atlantic Tunas Convention Act (3) BFT (Atlantic bluefin tuna) means the subspecies of bluefin tuna, Thunnus thynnus thynnus, or a part thereof, that occurs in the Atlantic Ocean. (4) BSD means the ICCAT bluefin tuna statistical document. (5)...

  7. 50 CFR 600.15 - Other acronyms.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... management terms. (1) ABC—acceptable biological catch (2) ATCA-Atlantic Tunas Convention Act (3) BFT (Atlantic bluefin tuna) means the subspecies of bluefin tuna, Thunnus thynnus thynnus, or a part thereof, that occurs in the Atlantic Ocean. (4) BSD means the ICCAT bluefin tuna statistical document. (5)...

  8. 50 CFR 600.15 - Other acronyms.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... management terms. (1) ABC—acceptable biological catch (2) ATCA-Atlantic Tunas Convention Act (3) BFT (Atlantic bluefin tuna) means the subspecies of bluefin tuna, Thunnus thynnus thynnus, or a part thereof, that occurs in the Atlantic Ocean. (4) BSD means the ICCAT bluefin tuna statistical document. (5)...

  9. 50 CFR 600.15 - Other acronyms.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... (2) ATCA-Atlantic Tunas Convention Act (3) BFT (Atlantic bluefin tuna) means the subspecies of bluefin tuna, Thunnus thynnus thynnus, or a part thereof, that occurs in the Atlantic Ocean. (4) BSD means the ICCAT bluefin tuna statistical document. (5) DAH—estimated domestic annual harvest (6)...

  10. 50 CFR 600.15 - Other acronyms.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... management terms. (1) ABC—acceptable biological catch (2) ATCA-Atlantic Tunas Convention Act (3) BFT (Atlantic bluefin tuna) means the subspecies of bluefin tuna, Thunnus thynnus thynnus, or a part thereof, that occurs in the Atlantic Ocean. (4) BSD means the ICCAT bluefin tuna statistical document. (5)...