The commercially important Atlantic bluefin tuna (Thunnus thynnus), a large migratory fish, has e... more The commercially important Atlantic bluefin tuna (Thunnus thynnus), a large migratory fish, has experienced notable recovery aided by accurate resource assessment and effective fisheries management efforts. Traditionally, this species has been perceived as consisting of eastern and western populations, spawning respectively in the Mediterranean Sea and the Gulf of Mexico, with mixing occurring throughout the Atlantic. However, recent studies have emerged challenging this assumption by revealing weak genetic differentiation and identifying a previously unknown spawning ground in the Slope Sea used by Atlantic bluefin tuna of uncertain origin. To further understand the current and past population structure and connectivity of Atlantic bluefin tuna, we have assembled a unique dataset including thousands of genome-wide Single Nucleotide Polymorphisms (SNPs) from five hundred larvae, young of the year and spawning adult samples covering the three spawning grounds and including individual...
Two investigations were carried out with 150 g gilthead sea bream Sparus aurata to determine the ... more Two investigations were carried out with 150 g gilthead sea bream Sparus aurata to determine the relative activity of six digestive enzymes (pepsin, trypsin, chymotrypsin, carboxypeptidase A, carboxypeptidase B and amylase) and the pH variation in the lumen of different parts of the gut of fish fed one or two meals per day. Pepsin activity was found exclusively in the stomach, whereas activities of the other enzymes studied were found in all regions of the gut, including the stomach. The lack of localization of enzyme production in the digestive tract of S. aurata is similar to many other species as reported in the literature. The pH variations found in the different regions of the gut could be explained by general digestive physiology following the flow of digesta along the digestive tract. The range of pHs recorded in the various regions of the gut were generally outside the cited optima for many digestive proteases in this species.
The Atlantic bluefin tuna (ABFT) is a highly prized species of large pelagic fish. Studies of the... more The Atlantic bluefin tuna (ABFT) is a highly prized species of large pelagic fish. Studies of their environmental physiology may improve understanding and management of their populations, but this is difficult for mature adults because of their large size. Biologging of heart rate holds promise in investigating physiological responses to environmental conditions in free‐swimming fishes but it is very challenging to anesthetize large ABFT for invasive surgery to place a tag in the body cavity near to the heart. We describe a novel method for rapid deployment of a commercially available heart‐rate tag on ABFT, using an atraumatic trocar to implant it in the musculature associated with the cleithrum. We performed three sequential experiments to show that the tagging method (1) is consistently repeatable and reliable, (2) can be used successfully on commercial fishing boats and does not seem to affect fish survival, and (3) is effective for long‐term deployments. In experiment 3, a tag logged heart rate over 80 days on a 60‐kg ABFT held in a farm cage. The logged data showed that heart rate was sensitive to prevailing seasonal temperature and feeding events. At low temperatures, there were clear responses to feeding but these all disappeared above a threshold temperature of 25.5°C. Overall, the results show that our method is simple, rapid, and repeatable, and can be used for long‐term experiments to investigate physiological responses by large ABFT to environmental conditions.
As part of its scientific objectives, the Federation of Maltese Aquaculture Producers (FMAP) orga... more As part of its scientific objectives, the Federation of Maltese Aquaculture Producers (FMAP) organised and carried out its first growth trial in a cage of one of its members in order to determine the increase in weight and length of Atlantic bluefin tuna (Thunnus thynnus)(BFT). The growth trial, which lasted from February to June 2009, used approximately 300 bluefin tuna from the 2008 fishing season. The average sea temperature during the experiment was 17C. Other measurements were taken at each sampling point, as were samples for further analyses (chemical, histological and genetic). From an average round weight (RWT) of 60.9kg the bluefin tuna grew to an average RWT of 87.4 kg, an increase of 43.5%. Fork length (FL) increased from an average of 142.5cm to an average of 157.9 cm by the end of the trial period, an increase of 10.8%. The results obtained here clearly indicate a significant growth in farmed bluefin tuna even at the low average temperature of 17C. The data presented he...
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
"Puncher et al_Thunnus thynnus_384 SNPs with flanking sequences.txt" contains the flank... more "Puncher et al_Thunnus thynnus_384 SNPs with flanking sequences.txt" contains the flanking sequences of 384 SNPs discovered using reduced representation sequence libraries, 221 of which passed quality criteria and 95 that were used for population structure analysis
The Atlantic bluefin tuna is a highly migratory species emblematic of the challenges associated w... more The Atlantic bluefin tuna is a highly migratory species emblematic of the challenges associated with shared fisheries management. In an effort to resolve the species’ stock dynamics, a genome-wide search for spatially informative single nucleotide polymorphisms (SNPs) was undertaken, by way of sequencing reduced representation libraries. An allele frequency approach to SNP discovery was used, combining the data of 555 larvae and young-of-the-year (LYOY) into pools representing major geographical areas and mapping against a newly assembled genomic reference. From a set of 184,895 candidate loci, 384 were selected for validation using 167 LYOY. A highly discriminatory genotyping panel of 95 SNPs was ultimately developed by selecting loci with the most pronounced differences between western Atlantic and Mediterranean Sea LYOY. The panel was evaluated by genotyping a different set of LYOY (n= 326) and from these 77.8% and 82.1% were correctly assigned to western Atlantic and Mediterranean Sea origins, respectively. The panel revealed temporally persistent differentiation among LYOY from the western Atlantic and Mediterranean Sea (FST = 0.008, p=0.034). The composition of six mixed feeding aggregations in the Atlantic Ocean and Mediterranean Sea was characterized using genotypes from medium (n = 184) and large (n = 48) adults, applying population assignment and mixture analyses. The results provide evidence of persistent population structuring across broad geographic areas and extensive mixing in the Atlantic Ocean, particularly in the mid-Atlantic Bight and Gulf of St. Lawrence. The genomic reference and genotyping tools presented here constitute novel resources useful for future research and conservation efforts
☯ These authors contributed equally to this work. ‡ These authors also contributed equally to thi... more ☯ These authors contributed equally to this work. ‡ These authors also contributed equally to this work.
SUMMARY New data from three Atlantic bluefin tuna (Thunnus thynnus L.) (BFT) farms in Malta are p... more SUMMARY New data from three Atlantic bluefin tuna (Thunnus thynnus L.) (BFT) farms in Malta are presented providing fillet and loin yields for bluefin tuna processed during the 2008 harvesting season. These results were used to obtain conversion factors for the determination of round weights (RWT). Differences were noted between the fillet and loin conversion factors between the farms. A review of previous works indicated differences in product conversion factors depending on the temporal and spatial origin of the fish. These parameters, amongst others, should be considered in order to obtain valid and meaningful product conversion factors for the determination of RWT values for use in bluefin tuna catch data and trade statistics. RESUME
SUMMARY Length-weight (L-W) relationships are key parameters in the stock assessment of Atlantic ... more SUMMARY Length-weight (L-W) relationships are key parameters in the stock assessment of Atlantic bluefin tuna, Thunnus thynnus, L. (BFT). An analysis of the data from the Maltese longline (LL) fisheries during the months of May and June of the years 2008 to 2011 are presented. The grouped data available were broken down into four periods over the months of May and June (1-15 May, 16-31 May, 1-15 June, 16-30 June) for these years and the L-W relationships were determined for each of these four periods. The RWT of a fish with a particular FL decreased as time passed with the biggest difference being obtained in the final period, that corresponding to the second half of June. These results, along with those of other authors, indicate that the use of a single L-W equation for bluefin tuna over 100 cm does not sufficiently represent the true variable L-W relationships in East Atlantic and Mediterranean bluefin tuna, and new equations should be available for the purpose of stock assessmen...
3SUMMARY The holding of Atlantic bluefin tuna (Thunnus thynnus L.)(BFT) in captivity was establis... more 3SUMMARY The holding of Atlantic bluefin tuna (Thunnus thynnus L.)(BFT) in captivity was established in the Mediterranean with the scope of increasing weight and quality. As is typical for aquaculture operations, satiation feeding and being held in cages increases the growth rate of the fattened/farmed bluefin tuna compared to the wild fish. This increase in weight was quantified by the SCRS Committee in a Growth Table showing the expected percentage weight of gain of bluefin tuna after caging. Other species of bluefin tuna, namely Pacific bluefin tuna (Thunnus orientalis Temminck and Schlegel)(PBT) and southern bluefin tuna (Thunnus maccoyii Castelnau) have also been fattened/farmed for a number of years. Growth data from Pacific bluefin tuna and southern bluefin tuna confirm that fattening/farming has the potential to result in significantly larger growth rates than seen in the wild. Information available for Pacific bluefin tuna and southern bluefin tuna held in captivity shows b...
Article available on line / Article disponible en ligne à l’adresse : ---------------------------... more Article available on line / Article disponible en ligne à l’adresse : -------------------------------------------------------------------------------------------------------------------------------------------------------------------------http://om.ciheam.org/article.php?IDPDF=97605918 --------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Length-weight (L-W) relationships are important parameters in Atlantic bluefin tuna (Thunnus thyn... more Length-weight (L-W) relationships are important parameters in Atlantic bluefin tuna (Thunnus thynnus L) (ABFT) stock assessments. Some datasets used to determine L-W relationships contain outliers which may significantly affect the accuracy of these L-W relationship and other parameters utilised during stock assessments. A method is proposed to filter out these outliers and provide more meaningful L-W relationships. This method is based on the application of the Tukey’s Outlier method on the Fulton’s Condition Factor (K) data derived from available fork length (FL) and round weight (RWT) data. In this paper Tukey’s Outlier method was applied to K data derived from the FLs and RWTs of eight Atlantic bluefin tuna datasets from both wild and farmed Atlantic bluefin tuna. Lower and upper filtering limits were used to filter out outlying FL and RWT data points in the original datasets to determine new L-W relationships. It was shown that applying Tukey’s Outlier filtering procedure signi...
ABSTRACT The growth equation currently used for Atlantic bluefin tuna, Thunnus thynnus (L.), east... more ABSTRACT The growth equation currently used for Atlantic bluefin tuna, Thunnus thynnus (L.), eastern stock (Lt = 318.85 [1-e^(-0.093*(t + 0.97)) is validated using several approaches. The first method involved a comparison of studies with von Bertalanffy parameter estimates in which, different methods for the age estimation are utilized, taking as references the maximum size of this species (Lmax = 319.93 +- 11.3 cm) and the growth equation of the western Atlantic stock (Lt = 314.90 [1-e ^(0.089* (t+1.13)). The result of this analysis showed that the growth equation used by ICCAT’s Standing Committee on Research and Statistics Atlantic bluefin tuna assessment group for the eastern stock perfectly fits Lmax. Second, an analysis was realized from first dorsal spine rings, 578 samples (age groups 0 to 3) of ABFT collected from the Bay of Biscay and the Mediterranean Sea, enabled the interpretation of the wide opaque bands (fast growth), formed during the boreal late spring and completed by autumn (June to November), and the translucent rings (hyaline rings, slow growth), formed during boreal autumn to late spring (November to May-June). In addition, first dorsal spine sections bands of two recovered fish that had carried conventional and electronic archival tags are also consistent. The chronological analysis of the opaque bands and hyaline rings of one fish tagged with an archival tag and recovered in the Bay of Biscay (the first time such a spine had been available for such analysis) revealed that transatlantic migrations may lead to double hyaline ring formation in the spine. Finally, the validation of the ABFT growth equation is made by superimposing tag-recovery data from tagging surveys in the Bay of Biscay, western Mediterranean and western Atlantic (N = 131) and spine readings (N = 299) to the eastern stock ABFT growth equation and analysing residuals. The coefficient of determination (R^2 = 97.98) and the residual’s distribution indicated good performance of the model. Although no important differences between the growth model of the eastern stock and that of the western stock are found, in all cases studied, the predictive accuracy indicators are better for the eastern model.
The commercially important Atlantic bluefin tuna (Thunnus thynnus), a large migratory fish, has e... more The commercially important Atlantic bluefin tuna (Thunnus thynnus), a large migratory fish, has experienced notable recovery aided by accurate resource assessment and effective fisheries management efforts. Traditionally, this species has been perceived as consisting of eastern and western populations, spawning respectively in the Mediterranean Sea and the Gulf of Mexico, with mixing occurring throughout the Atlantic. However, recent studies have emerged challenging this assumption by revealing weak genetic differentiation and identifying a previously unknown spawning ground in the Slope Sea used by Atlantic bluefin tuna of uncertain origin. To further understand the current and past population structure and connectivity of Atlantic bluefin tuna, we have assembled a unique dataset including thousands of genome-wide Single Nucleotide Polymorphisms (SNPs) from five hundred larvae, young of the year and spawning adult samples covering the three spawning grounds and including individual...
Two investigations were carried out with 150 g gilthead sea bream Sparus aurata to determine the ... more Two investigations were carried out with 150 g gilthead sea bream Sparus aurata to determine the relative activity of six digestive enzymes (pepsin, trypsin, chymotrypsin, carboxypeptidase A, carboxypeptidase B and amylase) and the pH variation in the lumen of different parts of the gut of fish fed one or two meals per day. Pepsin activity was found exclusively in the stomach, whereas activities of the other enzymes studied were found in all regions of the gut, including the stomach. The lack of localization of enzyme production in the digestive tract of S. aurata is similar to many other species as reported in the literature. The pH variations found in the different regions of the gut could be explained by general digestive physiology following the flow of digesta along the digestive tract. The range of pHs recorded in the various regions of the gut were generally outside the cited optima for many digestive proteases in this species.
The Atlantic bluefin tuna (ABFT) is a highly prized species of large pelagic fish. Studies of the... more The Atlantic bluefin tuna (ABFT) is a highly prized species of large pelagic fish. Studies of their environmental physiology may improve understanding and management of their populations, but this is difficult for mature adults because of their large size. Biologging of heart rate holds promise in investigating physiological responses to environmental conditions in free‐swimming fishes but it is very challenging to anesthetize large ABFT for invasive surgery to place a tag in the body cavity near to the heart. We describe a novel method for rapid deployment of a commercially available heart‐rate tag on ABFT, using an atraumatic trocar to implant it in the musculature associated with the cleithrum. We performed three sequential experiments to show that the tagging method (1) is consistently repeatable and reliable, (2) can be used successfully on commercial fishing boats and does not seem to affect fish survival, and (3) is effective for long‐term deployments. In experiment 3, a tag logged heart rate over 80 days on a 60‐kg ABFT held in a farm cage. The logged data showed that heart rate was sensitive to prevailing seasonal temperature and feeding events. At low temperatures, there were clear responses to feeding but these all disappeared above a threshold temperature of 25.5°C. Overall, the results show that our method is simple, rapid, and repeatable, and can be used for long‐term experiments to investigate physiological responses by large ABFT to environmental conditions.
As part of its scientific objectives, the Federation of Maltese Aquaculture Producers (FMAP) orga... more As part of its scientific objectives, the Federation of Maltese Aquaculture Producers (FMAP) organised and carried out its first growth trial in a cage of one of its members in order to determine the increase in weight and length of Atlantic bluefin tuna (Thunnus thynnus)(BFT). The growth trial, which lasted from February to June 2009, used approximately 300 bluefin tuna from the 2008 fishing season. The average sea temperature during the experiment was 17C. Other measurements were taken at each sampling point, as were samples for further analyses (chemical, histological and genetic). From an average round weight (RWT) of 60.9kg the bluefin tuna grew to an average RWT of 87.4 kg, an increase of 43.5%. Fork length (FL) increased from an average of 142.5cm to an average of 157.9 cm by the end of the trial period, an increase of 10.8%. The results obtained here clearly indicate a significant growth in farmed bluefin tuna even at the low average temperature of 17C. The data presented he...
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
"Puncher et al_Thunnus thynnus_384 SNPs with flanking sequences.txt" contains the flank... more "Puncher et al_Thunnus thynnus_384 SNPs with flanking sequences.txt" contains the flanking sequences of 384 SNPs discovered using reduced representation sequence libraries, 221 of which passed quality criteria and 95 that were used for population structure analysis
The Atlantic bluefin tuna is a highly migratory species emblematic of the challenges associated w... more The Atlantic bluefin tuna is a highly migratory species emblematic of the challenges associated with shared fisheries management. In an effort to resolve the species’ stock dynamics, a genome-wide search for spatially informative single nucleotide polymorphisms (SNPs) was undertaken, by way of sequencing reduced representation libraries. An allele frequency approach to SNP discovery was used, combining the data of 555 larvae and young-of-the-year (LYOY) into pools representing major geographical areas and mapping against a newly assembled genomic reference. From a set of 184,895 candidate loci, 384 were selected for validation using 167 LYOY. A highly discriminatory genotyping panel of 95 SNPs was ultimately developed by selecting loci with the most pronounced differences between western Atlantic and Mediterranean Sea LYOY. The panel was evaluated by genotyping a different set of LYOY (n= 326) and from these 77.8% and 82.1% were correctly assigned to western Atlantic and Mediterranean Sea origins, respectively. The panel revealed temporally persistent differentiation among LYOY from the western Atlantic and Mediterranean Sea (FST = 0.008, p=0.034). The composition of six mixed feeding aggregations in the Atlantic Ocean and Mediterranean Sea was characterized using genotypes from medium (n = 184) and large (n = 48) adults, applying population assignment and mixture analyses. The results provide evidence of persistent population structuring across broad geographic areas and extensive mixing in the Atlantic Ocean, particularly in the mid-Atlantic Bight and Gulf of St. Lawrence. The genomic reference and genotyping tools presented here constitute novel resources useful for future research and conservation efforts
☯ These authors contributed equally to this work. ‡ These authors also contributed equally to thi... more ☯ These authors contributed equally to this work. ‡ These authors also contributed equally to this work.
SUMMARY New data from three Atlantic bluefin tuna (Thunnus thynnus L.) (BFT) farms in Malta are p... more SUMMARY New data from three Atlantic bluefin tuna (Thunnus thynnus L.) (BFT) farms in Malta are presented providing fillet and loin yields for bluefin tuna processed during the 2008 harvesting season. These results were used to obtain conversion factors for the determination of round weights (RWT). Differences were noted between the fillet and loin conversion factors between the farms. A review of previous works indicated differences in product conversion factors depending on the temporal and spatial origin of the fish. These parameters, amongst others, should be considered in order to obtain valid and meaningful product conversion factors for the determination of RWT values for use in bluefin tuna catch data and trade statistics. RESUME
SUMMARY Length-weight (L-W) relationships are key parameters in the stock assessment of Atlantic ... more SUMMARY Length-weight (L-W) relationships are key parameters in the stock assessment of Atlantic bluefin tuna, Thunnus thynnus, L. (BFT). An analysis of the data from the Maltese longline (LL) fisheries during the months of May and June of the years 2008 to 2011 are presented. The grouped data available were broken down into four periods over the months of May and June (1-15 May, 16-31 May, 1-15 June, 16-30 June) for these years and the L-W relationships were determined for each of these four periods. The RWT of a fish with a particular FL decreased as time passed with the biggest difference being obtained in the final period, that corresponding to the second half of June. These results, along with those of other authors, indicate that the use of a single L-W equation for bluefin tuna over 100 cm does not sufficiently represent the true variable L-W relationships in East Atlantic and Mediterranean bluefin tuna, and new equations should be available for the purpose of stock assessmen...
3SUMMARY The holding of Atlantic bluefin tuna (Thunnus thynnus L.)(BFT) in captivity was establis... more 3SUMMARY The holding of Atlantic bluefin tuna (Thunnus thynnus L.)(BFT) in captivity was established in the Mediterranean with the scope of increasing weight and quality. As is typical for aquaculture operations, satiation feeding and being held in cages increases the growth rate of the fattened/farmed bluefin tuna compared to the wild fish. This increase in weight was quantified by the SCRS Committee in a Growth Table showing the expected percentage weight of gain of bluefin tuna after caging. Other species of bluefin tuna, namely Pacific bluefin tuna (Thunnus orientalis Temminck and Schlegel)(PBT) and southern bluefin tuna (Thunnus maccoyii Castelnau) have also been fattened/farmed for a number of years. Growth data from Pacific bluefin tuna and southern bluefin tuna confirm that fattening/farming has the potential to result in significantly larger growth rates than seen in the wild. Information available for Pacific bluefin tuna and southern bluefin tuna held in captivity shows b...
Article available on line / Article disponible en ligne à l’adresse : ---------------------------... more Article available on line / Article disponible en ligne à l’adresse : -------------------------------------------------------------------------------------------------------------------------------------------------------------------------http://om.ciheam.org/article.php?IDPDF=97605918 --------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Length-weight (L-W) relationships are important parameters in Atlantic bluefin tuna (Thunnus thyn... more Length-weight (L-W) relationships are important parameters in Atlantic bluefin tuna (Thunnus thynnus L) (ABFT) stock assessments. Some datasets used to determine L-W relationships contain outliers which may significantly affect the accuracy of these L-W relationship and other parameters utilised during stock assessments. A method is proposed to filter out these outliers and provide more meaningful L-W relationships. This method is based on the application of the Tukey’s Outlier method on the Fulton’s Condition Factor (K) data derived from available fork length (FL) and round weight (RWT) data. In this paper Tukey’s Outlier method was applied to K data derived from the FLs and RWTs of eight Atlantic bluefin tuna datasets from both wild and farmed Atlantic bluefin tuna. Lower and upper filtering limits were used to filter out outlying FL and RWT data points in the original datasets to determine new L-W relationships. It was shown that applying Tukey’s Outlier filtering procedure signi...
ABSTRACT The growth equation currently used for Atlantic bluefin tuna, Thunnus thynnus (L.), east... more ABSTRACT The growth equation currently used for Atlantic bluefin tuna, Thunnus thynnus (L.), eastern stock (Lt = 318.85 [1-e^(-0.093*(t + 0.97)) is validated using several approaches. The first method involved a comparison of studies with von Bertalanffy parameter estimates in which, different methods for the age estimation are utilized, taking as references the maximum size of this species (Lmax = 319.93 +- 11.3 cm) and the growth equation of the western Atlantic stock (Lt = 314.90 [1-e ^(0.089* (t+1.13)). The result of this analysis showed that the growth equation used by ICCAT’s Standing Committee on Research and Statistics Atlantic bluefin tuna assessment group for the eastern stock perfectly fits Lmax. Second, an analysis was realized from first dorsal spine rings, 578 samples (age groups 0 to 3) of ABFT collected from the Bay of Biscay and the Mediterranean Sea, enabled the interpretation of the wide opaque bands (fast growth), formed during the boreal late spring and completed by autumn (June to November), and the translucent rings (hyaline rings, slow growth), formed during boreal autumn to late spring (November to May-June). In addition, first dorsal spine sections bands of two recovered fish that had carried conventional and electronic archival tags are also consistent. The chronological analysis of the opaque bands and hyaline rings of one fish tagged with an archival tag and recovered in the Bay of Biscay (the first time such a spine had been available for such analysis) revealed that transatlantic migrations may lead to double hyaline ring formation in the spine. Finally, the validation of the ABFT growth equation is made by superimposing tag-recovery data from tagging surveys in the Bay of Biscay, western Mediterranean and western Atlantic (N = 131) and spine readings (N = 299) to the eastern stock ABFT growth equation and analysing residuals. The coefficient of determination (R^2 = 97.98) and the residual’s distribution indicated good performance of the model. Although no important differences between the growth model of the eastern stock and that of the western stock are found, in all cases studied, the predictive accuracy indicators are better for the eastern model.
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