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This research aimed to determine the appropriate substitution level of soybean oil for tuna fish oil to enrich chicken meat with omega-3, without negative effects on broiler performance or on acceptance of meat by the consumer. The treatments consisted on substitution of soybean oil for tuna fish oil (0, 0.75, 1.5, 2.25 and 3.0%) in a basal corn-soybean diet. These five treatments were applied under a completely randomized design with three replicates, utilizing 195 male 1 day old Ross broilers. Data were analyzed using the GLM procedure of SAS and orthogonal contrasts to detect linear or quadratic responses to tuna fish oil levels (p less than or equal to 0.05). Average daily gain and feed intake decreased linearly (p less than or equal to 0.05) as tuna fish oil dietary level increased. In the sensory evaluation test, the meat suffered no alteration in taste up to a level of 0.75% tuna oil (p less than or equal to 0.05). The tuna fish oil dietary supplementation increased (p<0.05) EPA and DHA concentration in breast, leg and thigh. The ratio omega-6:omega-3 was reduced (p less than or equal to 0.05) with increasing levels of tuna fish oil. The appropriate substitution level of soybean oil by tuna fish oil with omega-3 enriched chicken meat is 0.75%, since at this level the acceptance of the meat is not affected and DHA and EPA concentrations increase.

In this work, frequency determinants of tuna fish consumption in two coastal cities of northwestern Mexico are evaluated using data registered through face-to-face surveys. After the adjustments with Akaike and Bayesian information criterion (AIC and BIC), the ordered probit model was applied arranged with 364 observations. The results showed that the majority of those surveyed (74%) have post-secondary education and more than 35% recognize eco-labels ('organic' and 'dolphin-safe') as a quality attribute of the product. The study suggests that consumers who prefer canned tuna fish decreased their demand compared with those who opt for fresh tuna fish. The low purchase of canned product is related to tastes and preferences; nonetheless, the consumers informed on the dolphin-safe eco-label have a higher propensity to buy canned tuna fish. Just as studies in other countries suggest, providing clear information on the environmental impact of the product could raise awareness of the consumer and form part of a marketing strategy for fish with eco-label.

Tuna species of the genus Thunnus, such as the bluefin tunas, are some of the most important and yet most endangered trade fish in the world. Identification of these species in traded forms, however, may be difficult depending on the presentation of the products, which may hamper conservation efforts on trade control. In this paper, we validated a genetic methodology that can fully distinguish between the eight Thunnus species from any kind of processed tissue. After testing several genetic markers, a complete discrimination of the eight tuna species was achieved using Forensically Informative Nucleotide Sequencing based primarily on the sequence variability of the hypervariable genetic marker mitochondrial DNA control region (mtDNA CR), followed, in some specific cases, by a second validation by a nuclear marker rDNA first internal transcribed spacer (ITS1). This methodology was able to distinguish all tuna species, including those belonging to the subgenus Neothunnus that are very closely related, and in consequence can not be differentiated with other genetic markers of lower variability. This methodology also took into consideration the presence of introgression that has been reported in past studies between T. thynnus, T. orientalis and T. alalunga. Finally, we applied the methodology to cross-check the species identity of 26 processed tuna samples. Using the combination of two genetic markers, one mitochondrial and another nuclear, allows a full discrimination between all eight tuna species. Unexpectedly, the genetic marker traditionally used for DNA barcoding, cytochrome oxidase 1, could not differentiate all species, thus its use as a genetic marker for tuna species identification is questioned.

Summer ichthyoplankton surveys were conducted in the northern Gulf of Mexico from 2007 to 2010 to characterize the distribution and abundance of tuna larvae. Larval assemblages of tunas were comprised of four genera: Thunnus, Auxis, Euthynnus, and Katsuwonus. Thunnus were the most abundant and four species were detected; T. atlanticus [blackfin tuna], T. obesus [bigeye tuna], T. albacares [yellowfin tuna], and T. thynnus [bluefin tuna]. Intra- and inter-annual variability in the distribution and abundance of Thunnus species were observed with higher densities in 2008 and 2009, with a decline in abundance observed in 2010. Distribution and abundance of Thunnus larvae were influenced by physical and chemical conditions of the water mass, notably sea surface temperature and salinity. Distinct species-specific habitat preferences were observed and the location of mesoscale oceanographic features influenced larval abundance with higher densities of T. atlanticus, T. obesus, and T. albacares near anticyclonic (warm core) regions and the Loop Current, while T. thynnus was observed in higher densities near cyclonic (cold core) regions. This study demonstrates that spatial and temporal variability in the location of mesoscale oceanographic features may be important to partitioning nursery habitat among Thunnus species.

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 Endangered Species (CITES) requires that listed species must be identifiable in trade. This research fulfills this requirement for tuna, and supports the nomination of northern bluefin tuna for CITES listing in 2010.

Background: Dietary fish oil provides long chain omega-3 polyunsaturated fatty acids (LC n-3 PUFA) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The heart (Charnock et al., 1986: Annals of Nutrition and Metabolism, 30, 393-406) and skeletal muscle (Peoples & McLennan, 2010: British Journal of Nutrition, 104(12), 1771-1779) preferentially incorporate DHA and modulates both myocardial (Pepe & McLennan, 2002: Circulation, 105, 2303-2308) and skeletal muscle oxygen consumption translated as improved muscle fatigue resistance (Peoples & McLennan, 2014: British Journal of Nutrition, 111, 996-1004). However, studies of well-trained endurance athletes have used excessive doses of DHA (Peoples et al., 2008: Journal of Cardiovascular Pharmacology, 52, 540-547; Buckley et al., 2009: Journal of Science and Medicine in Sport, 12(4), 503-507). Given that even a very low fish oil supplement maximises membrane incorporation of DHA (Slee et al., 2010: Journal of Lipid Research, 51, 1841-1847) there is strong physiological basis for cyclists to improve oxygen efficiency through a nutritional approach. Purpose: The current study primarily aimed to establish if provision of a low dose of dietary fish oil in cyclists could convey improved oxygen efficiency in heart and skeletal muscle under conditions of established cycling fatigue and acute recovery. Methods: Using a double-blind design, trained males (N=26) were supplemented with (2x1g.d-1) soy oil (control n=13) or tuna fish oil (FO n=13) providing LCn-3PUFA, DHA: 560mg and EPA: 140mg (Nu-Mega, Australia) for 8 weeks. Erythrocyte omega-3 index (% EPA+DHA) was measured at baseline at following supplementation. At both time points participants underwent a repeated Wingate cycling protocol (6x30sec / 150seconds recovery) to establish cycling fatigue, immediately followed by a 5min cycling time trial (Wattbike, UK). Upon completion, participants were place in a supine recovery position for 10mins. Oxygen consumption (O2), heart rate (HR) and power (W) were continuously monitored.Results: Erythrocyte omega-3 index at baseline (Control: 4.2±0.2; FO: 4.7±0.2%) was not different between groups. After 8weeks the omega-3 index was unchanged in control (3.9±0.2%) but increased in FO group (6.3±0.3%, P< 0.01). There was no effect of FO supplementation on; peak HR (Control: 174±1 FO: 176±1beats.min-1), mean power during Wingate cycling fatigue protocol (Control: 545±28; FO: 511±33W), or cycling time trial performance under established fatigue (Control: 267±19; FO: 253±16W). However, FO supplementation improved oxygen efficiency (delta change) during the cycling time trial (Control: -23±26; FO: -154±59ml O2/min/100W P<0.05) and accelerated HR recovery (logit half-time) in the supine position immediately afterwards (Control: -0.4±1.2s; FO: -8.0±1.7s, P<0.05). The later was independent of a change in parasympathetic tone and reflective of reduced myocardial oxygen consumption.Discussion: A low dose fish oil supplement providing DHA increased the omega-3 index in trained cyclists. The improved cycling efficiency is reflective of the oxygen modulation previously demonstrated in rodent skeletal muscle (Peoples & McLennan, 2014), while the faster heart rate recovery without alteration in autonomic tone is supportive of the a reduction in intrinsic beat rate of the SA node following DHA administration (Verkerk, et al., 2009: Heart Rhythm, 6(10), 1485-1492). Conclusion: Provision of LCn-3 PUFA, DHA, in the form of a low dose fish oil supplement can have profound effects on heart and skeletal muscle incorporation, and as consequence improve cycling efficiency and heart rate recovery, indicative of reduced heart load. As a consequence, the concentrations used in the current study can be modeled for nutritional recommendations of DHA in elite cyclists.

Indonesia is one of the largest tuna producers in the world, which contributes 16% to world tuna production. The dominant tuna species catched in Indonesia are Albacore Tuna ( Thunnus alalunga ), Madidihang/Yellowfin Tuna ( T. albacares ), Big Eye Tuna ( T. obesus ) dan Southern Bluefin Tuna ( T. maccoyii ). The tuna fisheries have contributed significant jobs or livelihood to the coastal communities. Profit and revenue sharing is a common remuneration system found on tuna fisheries though out Indonesia. However, these fishers are vulnerable given their economic and welfare conditions and of usually limited options of others livelihood. Small fishers have limited access to livelihoods, access to finance and access to skills or fishing technology. Therefore, the inclusion of socio-economic performance or indicators into the tuna fisheries management is crucial in Indonesia.

Background Atlantic Bluefin Tuna (ABFT) shows complex demography and ecological variation in the Mediterranean Sea. Genetic surveys have detected significant, although weak, signals of population structuring; catch series analyses and tagging programs identified complex ABFT spatial dynamics and migration patterns. Here, we tested the hypothesis that the genetic structure of the ABFT in the Mediterranean is correlated with mean surface temperature and salinity. Methodology We used six samples collected from Western and Central Mediterranean integrated with a new sample collected from the recently identified easternmost reproductive area of Levantine Sea. To assess population structure in the Mediterranean we used a multidisciplinary framework combining classical population genetics, spatial and Bayesian clustering methods and a multivariate approach based on factor analysis. Conclusions FST analysis and Bayesian clustering methods detected several subpopulations in the Mediterranean, a result also supported by multivariate analyses. In addition, we identified significant correlations of genetic diversity with mean salinity and surface temperature values revealing that ABFT is genetically structured along two environmental gradients. These results suggest that a preference for some spawning habitat conditions could contribute to shape ABFT genetic structuring in the Mediterranean. However, further studies should be performed to assess to what extent ABFT spawning behaviour in the Mediterranean Sea can be affected by environmental variation.

Intentional mislabelling of seafood is a widespread problem, particularly with high-value species like tuna. In this study we examine tuna mislabelling, deliberate species substitution, types of substitution and its impact on prices. The survey covered the commercial chain, from Merca-Barna to fishmongers and restaurants in the Spanish Autonomous Community of Catalonia. To understand the geographic extent of the problem we also sampled Merca-Madrid, Europe's biggest fish market, and Merca-Málaga for its proximity to the bluefin tuna migratory route and trap fishery. Monthly surveys were carried out over one year. The results showed a high deficiency in labelling: 75% of points of sale and 83% of restaurants did not specify the species, and in those cases the name of the species had to be asked. A total of 375 samples were analysed genetically, the largest dataset gathered in Europe so far. The identified species were Thunnus albacares, Thunnus thynnus and Thunnus obesus. Species substitution began at suppliers, with 40% of observed cases, increasing to 58% at fishmongers and 62% at restaurants. The substitution was mainly on bluefin tuna (T. thynnus), 73% of cases. At restaurants, only during the bluefin fishing season, we observed a decrease of Bluefin tuna substitution and an increase of reverse substitution revealing some illegal fishing. The effect of species substitution on species prices was relevant: T. obesus increased its price by around €12 kg-1 when it was sold as bluefin. In view of the deficiency of labelling, the abuse of generic names and the lack of the bluefin catch document, we conclude that the Spanish regulations are ineffective, highlighting the need for policy execution, and the urgent need for information campaigns to Spanish consumers.

Sex-identification DNA markers are useful tools for sexing organisms that lack externally visible sexual dimorphism, and thus, they provide biological information for ecological and evolutionary studies. Tunas of the genus Thunnus (Scombridae), which comprises 8 species, lack sexual dimorphism of external morphology or coloration. In this study, we applied recently developed genotypic sex-identification markers for Pacific bluefin tuna to other tuna species to evaluate their effectiveness in sex identification. A sex-identification marker named ‘primer pair II’ demonstrated relatively high effectiveness in all tuna species, except southern bluefin tuna. Primer pair II was further tested in 209 albacore individuals collected during the scientific observer program onboard Japanese commercial long-line vessels, and it demonstrated robust performance for genotypic sex identification. The sex ratio of this albacore sample (1:1.4) significantly deviated from the expected 1:1 with the dominance of males, and the mean body size of males was higher than that of females. As all cross-species amplifications of the male-specific markers, except those for the southern bluefin tuna, were male-heterozygous polymorphisms, it is likely that a male-heterozygous sex-associated region exists in the Thunnus genome. The evolution of sex-determination systems in tunas was analyzed by ancestral state reconstruction, which showed that a common ancestor, before the evolution of the genus, possessed the male-heterozygous sex-associated genome region.