The Experts below are selected from a list of 2811 Experts worldwide ranked by ideXlab platform

Andone Estonba - One of the best experts on this subject based on the ideXlab platform.

  • reduced single nucleotide polymorphism panels for assigning atlantic Albacore and bay of biscay anchovy individuals to their geographic origin toward sustainable fishery management
    Journal of Agricultural and Food Chemistry, 2017
    Co-Authors: Iratxe Montes, Urtzi Laconcha, Mikel Iriondo, C Manzano, Haritz Arrizabalaga, Andone Estonba
    Abstract:

    There is an increasing trend upon adding a detailed description of the origin of seafood products driven by a general interest in the implementation of sustainable fishery management plans for the conservation of marine ecosystems. North Atlantic Albacore (“Bonito del Norte con Eusko Label”) and Bay of Biscay anchovy (“Anchoa del Cantabrico”) are two commercially important fish populations with high economical value and vulnerable to commercial fraud. This fact, together with the overexploited situation of these two populations, makes it necessary to develop a tool to identify individual origin and to detect commercial fraud. In the present study, we have developed and validated a traceability tool consisting of reduced panels of gene-associated single nucleotide polymorphisms (SNPs) suitable for assigning individuals of two species to their origin with unprecedented accuracy levels. Only 48 SNPs are necessary to assign 81.1% Albacore and 93.4% anchovy individuals with 100% accuracy to their geographic or...

  • Reduced Single Nucleotide Polymorphism Panels for Assigning Atlantic Albacore and Bay of Biscay Anchovy Individuals to Their Geographic Origin: Toward Sustainable Fishery Management
    2017
    Co-Authors: Iratxe Montes, Urtzi Laconcha, Mikel Iriondo, C Manzano, Haritz Arrizabalaga, Andone Estonba
    Abstract:

    There is an increasing trend upon adding a detailed description of the origin of seafood products driven by a general interest in the implementation of sustainable fishery management plans for the conservation of marine ecosystems. North Atlantic Albacore (“Bonito del Norte con Eusko Label”) and Bay of Biscay anchovy (“Anchoa del Cantábrico”) are two commercially important fish populations with high economical value and vulnerable to commercial fraud. This fact, together with the overexploited situation of these two populations, makes it necessary to develop a tool to identify individual origin and to detect commercial fraud. In the present study, we have developed and validated a traceability tool consisting of reduced panels of gene-associated single nucleotide polymorphisms (SNPs) suitable for assigning individuals of two species to their origin with unprecedented accuracy levels. Only 48 SNPs are necessary to assign 81.1% Albacore and 93.4% anchovy individuals with 100% accuracy to their geographic origin. The total accuracy of the results demonstrates how gene-associated SNPs can revolutionize food traceability. Gene-associated SNP panels are not of mere commercial interest, but they also can result in a positive impact on sustainability of marine ecosystems through conservation of fish populations through establishing a more effective and sustainable fishery management framework and contributing to the prevention of falsified labeling

  • single nucleotide polymorphism discovery in Albacore and atlantic bluefin tuna provides insights into worldwide population structure
    Animal Genetics, 2013
    Co-Authors: Aitor Albaina, Molly E. Lutcavage, Urtzi Laconcha, Mikel Iriondo, Haritz Arrizabalaga, I Velado, Iratxe Zarraonaindia, M A Pardo, W S Grant, Andone Estonba
    Abstract:

    Summary 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 werediscoveredin35Albacoretunabycomparingsequencesof54nuclearDNAfragments.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.

Nathalie Bodin - One of the best experts on this subject based on the ideXlab platform.

  • trophic ecology of Albacore tuna thunnus alalunga in the western tropical indian ocean and adjacent waters
    Marine and Freshwater Research, 2020
    Co-Authors: Evgeny V Romanov, Natacha Nikolic, Zahirah Dhurmeea, Nathalie Bodin, Alexis Puech, Stewart Norman, Stephanie Hollanda, Jerome Bourjea
    Abstract:

    In this study we investigated the trophic ecology of Albacore tuna in the western Indian Ocean and adjacent Atlantic waters based on stomach content analysis using a reconstituted length and weight of prey approach. From 686 non-empty stomachs collected between 2001 and 2015 across three biogeographic provinces, we describe the diet composition of Albacore tuna, analyse its feeding habits and investigate the structure and diversity of mid-trophic-level communities. Epipelagic fish were found to be the principal prey by number and reconstituted weight; cephalopods were the second important prey group. Small organisms prevailed in the diet of Albacore tuna, with predation on juvenile fish commonplace. Albacore tuna exhibits a flexible, opportunistic feeding strategy, from ram filter feeding on abundant schooling prey to visual predation on large individuals. Prey species richness varied highly across the region. Oligotrophic conditions within the subtropical gyre of the Indian Ocean generated the most diverse mid-trophic-level communities, with less diverse communities occurring in productive areas. Albacore tuna occupies a similar trophic niche throughout the global ocean, foraging on the same prey families and even species. This study indicates overall temporal stability of the Indian Ocean and south-east Atlantic ecosystems where principal prey species remain unchanged over decades.

  • Lipid and fatty acid dynamics in mature female Albacore tuna (Thunnus alalunga) in the western Indian Ocean - Fig 2
    2018
    Co-Authors: Zahirah Dhurmeea, Chandani Appadoo, Heidi Pethybridge, Nathalie Bodin
    Abstract:

    Boxplots showing variations in (a) total lipid content (TL) levels (μg mg-1 wet weight) and (b)-(e) lipid classes (μg mg-1 wet weight) in gonads (white) and liver (grey) of female Albacore tuna with ovary phase. SCP: spawning-capable, RGN: regressing, OPS: other post-spawning, WE: wax esters, TAG: triacylglycerols, ST: sterols, PL: phospholipids.

  • Chemical contaminants (trace metals, persistent organic pollutants) in Albacore tuna from western Indian and south-eastern Atlantic Oceans: Trophic influence and potential as tracers of populations
    Science of the Total Environment, 2017
    Co-Authors: Tiphaine Chouvelon, Nathalie Bodin, Stephanie Hollanda, Christophe Brach-papa, Dominique Auger, Sandrine Bruzac, Sylvette Crochet, Maxime Degroote, Clarisse Hubert, Joël Knoery
    Abstract:

    Albacore tuna (Thunnus alalunga) is a highly commercial fish species harvested in the world's Oceans. Identifying the potential links between populations is one of the key tools that can improve the current management across fisheries areas. In addition to characterising populations' contamination state, chemical compounds can help refine foraging areas, individual flows and populations' structure, especially when combined with other intrinsic biogeochemical (trophic) markers such as carbon and nitrogen stable isotopes. This study investigated the bioaccumulation of seven selected trace metals - chromium, nickel, copper (Cu), zinc (Zn), cadmium (Cd), mercury (Hg) and lead - in the muscle of 443 Albacore tunas, collected over two seasons and/or years in the western Indian Ocean (WIO: Reunion Island and Seychelles) and in the south-eastern Atlantic Ocean (SEAO: South Africa). The main factor that explained metal concentration variability was the geographic origin of fish, rather than the size and the sex of individuals, or the season/year of sampling. The elements Cu, Zn, Cd and Hg indicated a segregation of the geographic groups most clearly. For similar sized-individuals, tunas from SEAO had significantly higher concentrations in Cu, Zn and Cd, but lower Hg concentrations than those from WIO. Information inferred from the analysis of trophic markers (δ13C, δ15N) and selected persistent organic pollutants, as well as information on stomach contents, corroborated the geographical differences obtained by trace metals. It also highlighted the influence of trophic ecology on metal bioaccumulation. Finally, this study evidenced the potential of metals and chemical contaminants in general as tracers, by segregating groups of individuals using different food webs or habitats, to better understand spatial connectivity at the population scale. Limited flows of individuals between the SEAO and the WIO are suggested. Albacore as predatory fish also provided some information on environmental and food web chemical contamination in the different study areas.

  • Reproductive Biology of Albacore Tuna (Thunnus alalunga) in the Western Indian Ocean
    PLoS ONE, 2016
    Co-Authors: Zahirah Dhurmeea, Natacha Nikolic, Jerome Bourjea, Iker Zudaire, Emmanuel Chassot, Maria Cedras, Wendy West, Chandani Appadoo, Nathalie Bodin
    Abstract:

    The reproductive biology of Albacore tuna, Thunnus alalunga, in the western Indian Ocean was examined through analysis of the sex ratio, spawning season, length-at-maturity (L50), spawning frequency and fecundity. From 2013 to 2015, a total of 923 female and 867 male Albacore were sampled. A bias in sex ratio was found in favor of females with fork length (LF) < 100 cm. Using histological analyses and gonadosomatic index, spawning was found to occur between 10°S and 30°S, mainly to the east of Madagascar from October to January. Large females contributed more to reproduction through their longer spawning period compared to small individuals. The L50 (mean ± standard error) of female Albacore was estimated at 85.3 ± 0.7 cm LF. Albacore spawn on average every 2.2 days within the spawning region and spawning months, from November to January. Batch fecundity ranged between 0.26 and 2.09 million oocytes and the relative batch fecundity (mean ± standard deviation) was estimated at 53.4 ± 23.2 oocytes g-1 of somatic-gutted weight. The study provides new information on the reproductive development and classification of Albacore in the western Indian Ocean. The reproductive parameters will reduce uncertainty in current stock assessment models which will eventually assist the fishery to be sustainable for future generations.

Haritz Arrizabalaga - One of the best experts on this subject based on the ideXlab platform.

  • reduced single nucleotide polymorphism panels for assigning atlantic Albacore and bay of biscay anchovy individuals to their geographic origin toward sustainable fishery management
    Journal of Agricultural and Food Chemistry, 2017
    Co-Authors: Iratxe Montes, Urtzi Laconcha, Mikel Iriondo, C Manzano, Haritz Arrizabalaga, Andone Estonba
    Abstract:

    There is an increasing trend upon adding a detailed description of the origin of seafood products driven by a general interest in the implementation of sustainable fishery management plans for the conservation of marine ecosystems. North Atlantic Albacore (“Bonito del Norte con Eusko Label”) and Bay of Biscay anchovy (“Anchoa del Cantabrico”) are two commercially important fish populations with high economical value and vulnerable to commercial fraud. This fact, together with the overexploited situation of these two populations, makes it necessary to develop a tool to identify individual origin and to detect commercial fraud. In the present study, we have developed and validated a traceability tool consisting of reduced panels of gene-associated single nucleotide polymorphisms (SNPs) suitable for assigning individuals of two species to their origin with unprecedented accuracy levels. Only 48 SNPs are necessary to assign 81.1% Albacore and 93.4% anchovy individuals with 100% accuracy to their geographic or...

  • Reduced Single Nucleotide Polymorphism Panels for Assigning Atlantic Albacore and Bay of Biscay Anchovy Individuals to Their Geographic Origin: Toward Sustainable Fishery Management
    2017
    Co-Authors: Iratxe Montes, Urtzi Laconcha, Mikel Iriondo, C Manzano, Haritz Arrizabalaga, Andone Estonba
    Abstract:

    There is an increasing trend upon adding a detailed description of the origin of seafood products driven by a general interest in the implementation of sustainable fishery management plans for the conservation of marine ecosystems. North Atlantic Albacore (“Bonito del Norte con Eusko Label”) and Bay of Biscay anchovy (“Anchoa del Cantábrico”) are two commercially important fish populations with high economical value and vulnerable to commercial fraud. This fact, together with the overexploited situation of these two populations, makes it necessary to develop a tool to identify individual origin and to detect commercial fraud. In the present study, we have developed and validated a traceability tool consisting of reduced panels of gene-associated single nucleotide polymorphisms (SNPs) suitable for assigning individuals of two species to their origin with unprecedented accuracy levels. Only 48 SNPs are necessary to assign 81.1% Albacore and 93.4% anchovy individuals with 100% accuracy to their geographic origin. The total accuracy of the results demonstrates how gene-associated SNPs can revolutionize food traceability. Gene-associated SNP panels are not of mere commercial interest, but they also can result in a positive impact on sustainability of marine ecosystems through conservation of fish populations through establishing a more effective and sustainable fishery management framework and contributing to the prevention of falsified labeling

  • single nucleotide polymorphism discovery in Albacore and atlantic bluefin tuna provides insights into worldwide population structure
    Animal Genetics, 2013
    Co-Authors: Aitor Albaina, Molly E. Lutcavage, Urtzi Laconcha, Mikel Iriondo, Haritz Arrizabalaga, I Velado, Iratxe Zarraonaindia, M A Pardo, W S Grant, Andone Estonba
    Abstract:

    Summary 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 werediscoveredin35Albacoretunabycomparingsequencesof54nuclearDNAfragments.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.

  • 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
    Progress in Oceanography, 2010
    Co-Authors: Nicolas Goni, Haritz Arrizabalaga
    Abstract:

    Abstract 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.

Joël Knoery - One of the best experts on this subject based on the ideXlab platform.

  • Chemical contaminants (trace metals, persistent organic pollutants) in Albacore tuna from western Indian and south-eastern Atlantic Oceans: Trophic influence and potential as tracers of populations
    Science of the Total Environment, 2017
    Co-Authors: Tiphaine Chouvelon, Nathalie Bodin, Stephanie Hollanda, Christophe Brach-papa, Dominique Auger, Sandrine Bruzac, Sylvette Crochet, Maxime Degroote, Clarisse Hubert, Joël Knoery
    Abstract:

    Albacore tuna (Thunnus alalunga) is a highly commercial fish species harvested in the world's Oceans. Identifying the potential links between populations is one of the key tools that can improve the current management across fisheries areas. In addition to characterising populations' contamination state, chemical compounds can help refine foraging areas, individual flows and populations' structure, especially when combined with other intrinsic biogeochemical (trophic) markers such as carbon and nitrogen stable isotopes. This study investigated the bioaccumulation of seven selected trace metals - chromium, nickel, copper (Cu), zinc (Zn), cadmium (Cd), mercury (Hg) and lead - in the muscle of 443 Albacore tunas, collected over two seasons and/or years in the western Indian Ocean (WIO: Reunion Island and Seychelles) and in the south-eastern Atlantic Ocean (SEAO: South Africa). The main factor that explained metal concentration variability was the geographic origin of fish, rather than the size and the sex of individuals, or the season/year of sampling. The elements Cu, Zn, Cd and Hg indicated a segregation of the geographic groups most clearly. For similar sized-individuals, tunas from SEAO had significantly higher concentrations in Cu, Zn and Cd, but lower Hg concentrations than those from WIO. Information inferred from the analysis of trophic markers (δ13C, δ15N) and selected persistent organic pollutants, as well as information on stomach contents, corroborated the geographical differences obtained by trace metals. It also highlighted the influence of trophic ecology on metal bioaccumulation. Finally, this study evidenced the potential of metals and chemical contaminants in general as tracers, by segregating groups of individuals using different food webs or habitats, to better understand spatial connectivity at the population scale. Limited flows of individuals between the SEAO and the WIO are suggested. Albacore as predatory fish also provided some information on environmental and food web chemical contamination in the different study areas.

Bodin Nathalie - One of the best experts on this subject based on the ideXlab platform.

  • Diet of Albacore Thunnus alalunga from the waters of Mauritius (western Indian Ocean) inferred from stomach contents and fatty acid analysis
    2020
    Co-Authors: Dhurmeea Z., Pethybridge H., Romanov E., Appadoo C., Bodin Nathalie
    Abstract:

    The diet of Albacore Thunnus alalunga from their spawning ground in the waters of Mauritius was investigated. The stomach contents of 249 Albacore individuals, caught by industrial longliners and artisanal fishers, was analysed, and the dominant prey taxa were selected for lipid and fatty acid (FA) analysis. The FA profiles of prey were compared with those of liver tissue of spawning-capable and post-spawning female Albacore, using multivariate analysis. Whereas stomach content analysis identified cephalopods and crustaceans as the dominant prey items in number, FA-profile analysis identified crustaceans and fishes as the most-frequently consumed prey of post-spawning female Albacore. In contrast, the FA profiles of spawning-capable Albacore and those of prey showed very low similarity. Analysis of the prey suggests that although cephalopods, crustaceans and fishes could all provide Albacore with the required lipids and FAs, cephalopod prey seem to be less desirable owing to their lower energy content (i.e. low in total lipid, triacylglycerol, 16:0, 18:0 and 18:1 omega 9). Instead, the most beneficial food appeared to be locally available fishes, which are more energy-rich and have a higher docosahexaenoic acid/ eicosapentaenoic acid ratio. These results provide new information on the trophic ecology of Albacore, promote our understanding of the importance of prey type for successful reproduction of Albacore, and highlight the advantages of FA profiling to study diet

  • Connectivity and population structure of Albacore tuna across southeast Atlantic and southwest Indian Oceans inferred from multidisciplinary methodology
    'Springer Science and Business Media LLC', 2020
    Co-Authors: Nikolic Natacha, Bodin Nathalie, Montes Iratxe, Lalire Maxime, Puech Alexis, Arnaud-haond Sophie, Kerwath Sven, Corse Emmanuel, Gaspar Philippe, Hollanda Stéphanie
    Abstract:

    Albacore tuna (Thunnus alalunga) is an important target of tuna fisheries in the Atlantic and Indian Oceans. The commercial catch of Albacore is the highest globally among all temperate tuna species, contributing around 6% in weight to global tuna catches over the last decade. The accurate assessment and management of this heavily exploited resource requires a robust understanding of the species’ biology and of the pattern of connectivity among oceanic regions, yet Indian Ocean Albacore population dynamics remain poorly understood and its level of connectivity with the Atlantic Ocean population is uncertain. We analysed morphometrics and genetics of Albacore (n = 1,874) in the southwest Indian (SWIO) and southeast Atlantic (SEAO) Oceans to investigate the connectivity and population structure. Furthermore, we examined the species’ dispersal potential by modelling particle drift through major oceanographic features. Males appear larger than females, except in South African waters, yet the length–weight relationship only showed significant male–female difference in one region (east of Madagascar and Reunion waters). The present study produced a genetic differentiation between the southeast Atlantic and southwest Indian Oceans, supporting their demographic independence. The particle drift models suggested dispersal potential of early life stages from SWIO to SEAO and adult or sub-adult migration from SEAO to SWIO

  • Connectivity and Population Structure of Albacore Tuna Across Southeast Atlantic and Southwest Indian Oceans Inferred from Multidisciplinary Methodology
    'Springer Science and Business Media LLC', 2020
    Co-Authors: Nikolic Natacha, Bodin Nathalie, Montes Iratxe, Lalire Maxime, Puech Alexis, Arnaud-haond Sophie, Kerwath Sven, Corse Emmanuel, Gaspar Philippe, Hollanda Stéphanie
    Abstract:

    Albacore tuna (Thunnus alalunga) is an important target of tuna fisheries in the Atlantic and Indian Oceans. The commercial catch of Albacore is the highest globally among all temperate tuna species, contributing around 6% in weight to global tuna catches over the last decade. The accurate assessment and management of this heavily exploited resource requires a robust understanding of the species' biology and of the pattern of connectivity among oceanic regions, yet Indian Ocean Albacore population dynamics remain poorly understood and its level of connectivity with the Atlantic Ocean population is uncertain. We analysed morphometrics and genetics of Albacore (n = 1,874) in the southwest Indian (SWIO) and southeast Atlantic (SEAO) Oceans to investigate the connectivity and population structure. Furthermore, we examined the species' dispersal potential by modelling particle drift through major oceanographic features. Males appear larger than females, except in South African waters, yet the length-weight relationship only showed significant male-female difference in one region (east of Madagascar and Reunion waters). The present study produced a genetic differentiation between the southeast Atlantic and southwest Indian Oceans, supporting their demographic independence. The particle drift models suggested dispersal potential of early life stages from SWIO to SEAO and adult or sub-adult migration from SEAO to SWIO.This work was conducted in the framework of the GERMON project “N°759/DMSOI/2013” funded by the European Fisheries Funds EU FEP 2013-2015, IFREMER, and IR

  • Spatial variation in stable isotopes and fatty acid trophic markers in Albacore tuna (Thunnus alalunga) from the western Indian Ocean
    'Elsevier BV', 2020
    Co-Authors: Dhurmeea Zahirah, Nikolic Natacha, Pethybridge Heidi, Langlais Clothilde, Somes, Christopher J., Bourjea Jérôme, Appadoo Chandani, Bodin Nathalie
    Abstract:

    Albacore tuna (Thunnus alalunga) is a highly economically important species in the western Indian Ocean. However, knowledge of its ecological and nutritional characteristics, essential for proper management of the species, is lacking in the region. The trophodynamics of the Indian Ocean Albacore was thus examined using known fatty acid trophic markers (FATMs) of primary producers, nutritional condition indices (NCIs) (omega-3/omega-6 ratio and total fatty acid content (TFA)), and baseline and lipid corrected stable isotope of carbon (δ13Ccorr) and nitrogen (δ15Ncorr), measured in the muscle tissue. We applied generalized additive mixed models to understand the spatiotemporal patterns and drivers of these tracers, taking into consideration several intrinsic and extrinsic variables: fish size, fishing position, month, chlorophyll-a and sea surface temperature (SST). Both chlorophyll-a and SST were significant as single explanatory variables for all tracers with SST being the best predictor for docosahexaenoic acid/eicosapentaenoic acid ratio, the omega-6 protists FATM, omega-3/omega-6 ratio, δ13Ccorr and δ15Ncorr. TFA was best predicted by fish size only. Higher primary productivity, as inferred by high δ13Ccorr values and diatom contribution, nutritional condition and trophic position, as inferred by high δ15Ncorr values, were observed in Albacore from the temperate southern waters than in the northern tropical regions. Relationships between environmental variables and corrected stable isotopes, FATMs confirm that ocean warming and changes in primary productivity will impact nutrient flow and energy transfer in the marine food web which may have negative nutritional outcomes for Albacore. This knowledge is particularly crucial in areas where oceanographic conditions and seawater temperatures are changing at a fast rate and should also be taken into consideration by fisheries manager

  • Spatial variation in stable isotopes and fatty acid trophic markers in Albacore tuna (Thunnus alalunga) from the western Indian Ocean
    2020
    Co-Authors: Dhurmeea Z., Pethybridge H., Appadoo C., Nikolic Natacha, Somes, Christopher J., Langlais C., Bourjea J., Bodin Nathalie
    Abstract:

    Albacore tuna (Thunnus alalunga) is a highly economically important species in the western Indian Ocean. However, knowledge of its ecological and nutritional characteristics, essential for proper management of the species, is lacking in the region. The trophodynamics of the Indian Ocean Albacore was thus examined using known fatty acid trophic markers (FATMs) of primary producers, nutritional condition indices (NCIs) (omega-3/omega-6 ratio and total fatty acid content (TFA)), and baseline and lipid corrected stable isotope of carbon (delta C-13(corr)) and nitrogen (delta(15)b(corr)), measured in the muscle tissue. We applied generalized additive mixed models to understand the spatiotemporal patterns and drivers of these tracers, taking into consideration several intrinsic and extrinsic variables: fish size, fishing position, month, chlorophyll-a and sea surface temperature (SST). Both chlorophyll-a and SST were significant as single explanatory variables for all tracers with SST being the best predictor for docosahexaenoic acid/eicosapentaenoic acid ratio, the omega-6 protists FATM, omega-3/omega-6 ratio, delta C-13(corr) and delta N-15(corr). TFA was best predicted by fish size only. Higher primary productivity, as inferred by high 613C,0 values and diatom contribution, nutritional condition and trophic position, as inferred by high delta N-15(corr) values, were observed in Albacore from the temperate southern waters than in the northern tropical regions. Relationships between environmental variables and corrected stable isotopes, FATMs confirm that ocean warming and changes in primary productivity will impact nutrient flow and energy transfer in the marine food web which may have negative nutritional outcomes for Albacore. This knowledge is particularly crucial in areas where oceanographic conditions and seawater temperatures are changing at a fast rate and should also be taken into consideration by fisheries managers