LACK OF GENETIC DIFFERENTIATION IN THE ALTANTIC DISTRIBUTION OF WAHOO

SUMMARY In this study we present the analysis of the stock structure of Wahoo (Acanthocybium solandri) using the mitochondrial control region as genetic marker. We analyzed 276 individuals distributed in four locations int eh east and west Atlantic. Samples were from: Northeast Atlantic (AT-NE/BIL94B) (Canary Islands, Spain), from Southeast Atlantic (AT-SE/BIL97) (Côte d’Ivoire and Gabon) and Southwest Atlantic (AT-SW/BIL96). Four of individuals from Southwest Atlantic (AT-SW/BIL96) were genetically identified as Scomberomorus cavalla. The genetic comparison of the four locations failed to show genetic differences. This result suggests a single genetic pool of the Wahoo in the whole Atlantic. Based on these results, ICCAT should reconsider their management strategies for this species in the area studied. RÉSUMÉ Dans cette étude, nous présentons l’analyse de la structure du stock de thazard-bâtard (Acanthocybium solandri) en utilisant la région de contrôle de l’ADN mitochondrial comme marqueur génétique. Nous avons analysé 276 spécimens répartis dans quatre zones de l’Atlantique Est et Ouest. Les échantillons provenaient de : l’Atlantique Nord-Est (AT-NE/BIL94B) (îles Canaries, Espagne), l’Atlantique Sud-Est (AT-SE/BIL97) (Côte d’Ivoire et Gabon) et l’Atlantique Sud-Ouest (AT-SW/BIL96). Quatre spécimens provenant de l’Atlantique Sud-Ouest (AT-SW/BIL96) ont été génétiquement identifiés comme Scomberomorus cavalla. La comparaison génétique des quatre zones n’a pas révélé de différences génétiques. Ce résultat donne à penser à un patrimoine génétique du thazard-bâtard dans l’ensemble de l’Atlantique. En se fondant sur ces résultats, l’ICCAT devrait revoir ses stratégies de gestion pour cette espèce dans la zone à l’étude. RESUMEN En este estudio presentamos el análisis de la estructura del stock del peto (Acanthocybium solandri) utilizando la región de control mitocondrial como marcador genético. Hemos analizado 276 ejemplares distribuidos en cuatro localizaciones en el Atlántico este y oeste. Las muestras procedían de: Atlántico nororiental (AT-NE/BIL94B) (islas Canarias, España), del Atlántico suroriental (AT-SE/BIL97) (Côte d'Ivoire y Gabón) y del Atlántico sudoccidental (AT-SW/BIL96). Cuatro de los ejemplares del Atlántico sudoccidental (AT-SW/BIL96) fueron genéticamente identificados como Scomberomorus cavalla. La comparación genética de las cuatro localizaciones no mostraba diferencias genéticas. Este resultado sugiere un único acervo genético del peto en todo el Atlántico. Basándose en estos resultados, ICCAT debería reconsiderar la estrategia de ordenación para esta especie en la zona estudiada.Versión del edito

Population genetic of Atlantic bonito in the north east Atlantic and Mediterranean

This study assesses the stock structure of Atlantic bonito (Sarda sarda) using the mitochondrial control region as a genetic marker. About 615 individuals distributed in seven locations were analyzed. Two of the locations were in the Mediterranean Sea (MD/BIL95) (Spain and Tunis), three in the northeast Atlantic (AT-NE/BIL94B) (Portugal, Tunis, Morocco and Mauritania), and one in the southeast Atlantic (AT-SE/BIL97) (Côte d’Ivoire). All these samples were obtained thanks to the participation of all authors in two Small Tuna Research Programs funded by ICCAT. The analysis of the genetic variability of the sequence of mitochondrial control regions depicts a clear heterogeneity among locations. The shared genetic pool that comprises the locations within the Mediterranean (Spain and Tunis), including also a sample from the northeast Atlantic (Portugal), is clearly different from the African locations (Senegal and Côte d’Ivoire). Moreover, these two African locations are also genetically differentiated between them. Morocco and Mauritania locations seems to be located in an intermediate situation between these two groups of locations. These results can be used to infer a management policy by ICCAT on the fisheries of this specie

Deep genetic differentiation in the little tunny from the Mediterranean and east Atlantic.

In this study we present the analysis of the stock structure of Little tunny (Euthynnus alletteratus) using the mitochondrial control region as a genetic marker. More than 500 individuals distributed in six locations were analyzed. Samples were from three main regions: Mediterranean (Tunisia and Spain), and northeast Atlantic (Portugal and Senegal) and southeast Atlantic (Côte d’Ivoire and Gabon). Deep genetic differences were found between these locations. The phylogenetic tree showed a complete reciprocal monophyly association of the individuals in two main regions: Portugal, Spain and Tunisia; and Senegal, Côte d’Ivoire and Gabon. The level of genetic differentiation between these two areas is similar to the differences found between species of the genus Euthynnus. These results suggest a scenario of having two species of Little tunny in its Mediterranean-Atlantic distribution. Further evidence with other non-linked genetic markers along morphological and meristic data is necessary to fully confirm these two putative species. However, based on these results a separate management unit can be considered: i) Northeast Atlantic/Mediterranean (Portugal, Spain and Tunisia), and ii) the northeast/Southeast Atlantic (Senegal, Côte d’Ivoire and Gabon). RÉSUMÉ Dans cette étude, nous présentons l'analyse de la structure du stock de la thonine commune (Euthynnus alletteratus) en utilisant la zone mitochondriale de contrôle comme marqueur génétique. Plus de 500 spécimens répartis sur six sites ont été analysés. Les échantillons provenaient de trois régions principales : Méditerranée (Tunisie et UE-Espagne), Atlantique Nord-Est (Portugal et Sénégal) et Atlantique Sud-Est (Côte d'Ivoire et Gabon). De profondes différences génétiques ont été constatées entre ces endroits. L'arbre phylogénétique affichait une association monophylique réciproque complète des spécimens dans deux régions principales : l’UE-Portugal, l’UE-Espagne et la Tunisie ; et le Sénégal, la Côte d'Ivoire et le Gabon. Le niveau de différenciation génétique entre ces deux régions est similaire aux différences constatées entre les espèces du genre Euthynnus. Ces résultats suggèrent un scénario de présence de deux espèces de thonidés mineurs dans sa distribution méditerranéenne-atlantique. Des preuves supplémentaires avec d'autres marqueurs génétiques non liés ainsi que des données morphologiques et méristiques sont nécessaires pour confirmer pleinement ces deux espèces supposées. Toutefois, sur la base de ces résultats, une unité de gestion distincte peut être envisagée : i) Atlantique Nord-Est/Méditerranée (UE-Portugal, UE-Espagne et Tunisie) et ii) Atlantique Nord-Est/Sud-Est (Sénégal, Côte d'Ivoire et Gabon). RESUMEN En este estudio presentamos el análisis de la estructura del stock de la bacoreta (Euthynnus alletteratus) utilizando la región de control mitocondrial como marcador genético. Se analizaron más de 500 ejemplares distribuidos en seis localizaciones. Las muestras procedían de tres regiones principales: Mediterráneo (Túnez y España), Atlántico nororiental (Portugal y Senegal) y Atlántico suroriental (Côte d'Ivoire y Gabón). Se hallaron profundas diferencias genéticas entre las tres localizaciones: El árbol filogenético presentaba una asociación monofilética recíproca completa de los ejemplares en dos regiones principales: Portugal, España y Túnez; y Senegal, Côte d'Ivoire y Gabón. El nivel de diferenciación genética entre estas dos zonas es similar a las diferencias halladas entre especies del género Euthynnus. Estos resultados sugieren un escenario con dos especies de bacoreta en su distribución atlántica-mediterránea. Son necesarias más pruebas con otros marcadores genéticos no vinculados con datos morfológicos y neríticos para confirmar más estas dos especies putativas. Sin embargo, en base a estos resultados, puede considerarse una unidad de ordenación separada: i) Atlántico nororiental/Mediterráneo (Portugal, España y Túnez) y ii) Atlántico suroriental/nororiental (Senegal, Côte d'Ivoire y Gabón).N

Final report of the short-term contract for ICCAT SMYTP for the biological samples collection for growth, maturity and genetics studies – Year #2

This document is the final report of the second year of the short-term contract of the Small Tuna Year Program by ICCAT. In 2018, the Small Tuna Species Group decided to prioritize Little tunny (LTA) (Euthynnus alletteratus) Atlantic bonito (BON) (Sarda sarda) and Wahoo (WAH) (Acanthocybium solandri), based on their economic importance and the deficiency of knowledge of their biology. The objectives of the contract for three species were: i) Collect biological samples for estimating growth parameters, assessing the maturity and stock structure analysis (populations genetics), and ii) Conclude the analysis of the stock structure for at least one of the three species and provide preliminary results for the remaining. The obtained samples for growth, maturity and stock structure analysis was almost completed for Little tunny and Atlantic bonito, whereas for Wahoo the samples are scarce. The analysis of stock structure for Little tunny and Atlantic bonito revealed that the observed dif

Population genetic of Atlantic bonito in the north east Atlantic and Mediterranean

This study assesses the stock structure of Atlantic bonito (Sarda sarda) using the mitochondrial control region as a genetic marker. About 615 individuals distributed in seven locations were analyzed. Two of the locations were in the Mediterranean Sea (MD/BIL95) (Spain and Tunis), three in the northeast Atlantic (AT-NE/BIL94B) (Portugal, Tunis, Morocco and Mauritania), and one in the southeast Atlantic (AT-SE/BIL97) (Côte d’Ivoire). All these samples were obtained thanks to the participation of all authors in two Small Tuna Research Programs funded by ICCAT. The analysis of the genetic variability of the sequence of mitochondrial control regions depicts a clear heterogeneity among locations. The shared genetic pool that comprises the locations within the Mediterranean (Spain and Tunis), including also a sample from the northeast Atlantic (Portugal), is clearly different from the African locations (Senegal and Côte d’Ivoire). Moreover, these two African locations are also genetically differentiated between them. Morocco and Mauritania locations seems to be located in an intermediate situation between these two groups of locations. These results can be used to infer a management policy by ICCAT on the fisheries of this specie

Final report of the short-term contract for ICCAT SMYTP for the biological samples collection for growth, maturity and genetics studies – Year #2

This document is the final report of the second year of the short-term contract of the Small Tuna Year Program by ICCAT. In 2018, the Small Tuna Species Group decided to prioritize Little tunny (LTA) (Euthynnus alletteratus) Atlantic bonito (BON) (Sarda sarda) and Wahoo (WAH) (Acanthocybium solandri), based on their economic importance and the deficiency of knowledge of their biology. The objectives of the contract for three species were: i) Collect biological samples for estimating growth parameters, assessing the maturity and stock structure analysis (populations genetics), and ii) Conclude the analysis of the stock structure for at least one of the three species and provide preliminary results for the remaining. The obtained samples for growth, maturity and stock structure analysis was almost completed for Little tunny and Atlantic bonito, whereas for Wahoo the samples are scarce. The analysis of stock structure for Little tunny and Atlantic bonito revealed that the observed dif

Final report of the short-term contract for ICCAT SMYTP for the biological samples collection for growth, maturity and genetics studies – Year #3

This document is the final report of the third year of the short-term contract of the Small Tuna Year Program by ICCAT, with the objectives of: a) conduct additional sampling aiming to fill the specific gaps of the biological samples for estimating the growth and maturity parameters for BON and LTA; b) estimate the referred parameters for both species, and preliminary provide preliminary results for WAH; and, c) refine the sampling and stock structure analysis for BON, LTA and WAH. A total of 374 individuals were collected: 145 of BON, 139 of LTA and 90 WAH. Initial target size class was accomplished only for BON in the Mediterranean. Small individuals are need in the Northeast and no samples were obtained in Southeast Atlantic. For LTA, total target sizes were not completely achieved in any case. However, preliminary results were obtained for growth and reproductive parameters. For BON, with samples arrived from Morocco, no genetic differentiation was detected, and the hypothesis provided in the previous contract is maintained. The population genetic analysis of WAH presents a scenario of homogeneous distribution.En prensa

Report on the 2020 ICCAT workshop on small tunas biology studies for growth and reproduction

This report describes the 2020 ICCAT workshop on small tunas biology studies for growth and reproduction, hosted by the Instituto Español de Oceanografía, Málaga, Spain. The major objectives of the workshop were: 1) starting the creation of ageing and reproduction reference sets and, 2) providing more training for the ongoing sample collection and processing to the teams involved in these studies. As approved by the SCRS in 2017, the Small Tuna Species Group intersessional meeting decided to prioritize the collection of biological samples aiming at growth, maturity and stock structure studies on three species: little tunny (Euthynnus alletteratus), Atlantic Bonito (Sarda sarda) and wahoo (Acanthocybium solandri), based on their economic importance and the lack of knowledge on their biology. This work will contribute to the next major advance in the assessment of these three species

REPORT ON THE 2020 ICCAT WORKSHOP ON SMALL TUNAS BIOLOGY STUDIES FOR GROWTH AND REPRODUCTION.

SUMMARY This report describes the 2020 ICCAT workshop on small tunas biology studies for growth and reproduction, hosted by the Instituto Español de Oceanografía, Málaga, Spain. The major objectives of the workshop were: 1) starting the creation of ageing and reproduction reference sets and, 2) providing more training for the ongoing sample collection and processing to the teams involved in these studies. As approved by the SCRS in 2017, the Small Tuna Species Group intersessional meeting decided to prioritize the collection of biological samples aiming at growth, maturity and stock structure studies on three species: little tunny (Euthynnus alletteratus), Atlantic Bonito (Sarda sarda) and wahoo (Acanthocybium solandri), based on their economic importance and the lack of knowledge on their biology. This work will contribute to the next major advance in the assessment of these three species. RÉSUMÉ Le présent rapport décrit l'atelier de l’ICCAT tenu en 2020 sur les études de la biologie des thonidés mineurs pour la croissance et la reproduction, organisé par l'Instituto Español de Oceanografía, à Malaga, en Espagne. Les principaux objectifs de l'atelier étaient les suivants : 1) commencer à créer des ensembles de référence sur la détermination de l’âge et la reproduction et 2) fournir une formation plus poussée sur la collecte et le traitement des échantillons aux équipes participant à ces études. Tel qu’approuvé par le SCRS en 2017, lors de la réunion intersessions du Groupe d'espèces sur les thonidés mineurs, il a été décidé de donner la priorité à la collecte d'échantillons biologiques visant à étudier la croissance, la maturité et la structure des stocks de trois espèces : la thonine commune (Euthynnus alletteratus), la bonite à dos rayé (Sarda) et le thazard-bâtard (Acanthocybium solandri), sur la base de leur importance économique et des connaissances lacunaires sur leur biologie. Ces travaux contribueront à la prochaine grande avancée dans l'évaluation de ces trois espèces. RESUMEN Este informe describe el taller de ICCAT de 2020 sobre estudios de biología de pequeños túnidos para crecimiento y reproducción, acogido por el Instituto Español de Oceanografía en Málaga, España. Los principales objetivos del taller eran: 1) empezar la creación de conjuntos de referencia de determinación de la edad y reproducción y 2) facilitar más formación a los equipos involucrados en estos estudios para la recopilación de muestras y procesamiento en curso. Como aprobó el SCRS en 2017, en la Reunión intersesiones del Grupo de especies de pequeños túnidos se decidió priorizar la recopilación de muestras biológicas con miras a estudios de crecimiento, madurez y estructura del stock de tres especies: bacoreta (Euthynnus alletteratus), bonito (Sarda sarda) y peto (Acanthocybium solandri), basándose en su importancia económica y la falta de conocimientos sobre su biología. Este trabajo contribuirá a avanzar en la próxima evaluación de estas tres especies.N

Seasonal habitat and length influence on the trophic niche of co-occurring tropical tunas in the eastern Atlantic Ocean

International audienceIn the Gulf of Guinea, bigeye tuna (Thunnus obesus; BET) and yellowfin tuna (Thunnus albacares; YFT) are an important part of commercial fisheries and play a prominent ecological role as top predators. Using fatty acid profiles and carbon and nitrogen stable isotopes, we examined their trophic niche partitioning in this understudied region. Trophic niche overlap was high (> 70%), similar to percentages in other ocean basins. BET occupied a higher trophic position than YFT and fed on deeper prey (high delta N-15 values and high proportions of monounsaturated fatty acids). The trophic position of YFT decreased slightly in the last 15 years (delta N-15 values decreased by similar to 0.5 parts per thousand), suggesting a change in epipelagic communities, as observed in the eastern Pacific Ocean. Ontogenic changes were limited to BET. For both species, the dietary proportion of the diatom marker 20:5(n-3) increased in the seasonal upwelling area, highlighting the influence of seasonal habitat on the diet of tuna. The relatively lipid-rich muscle (similar to 6% dry mass) of Atlantic tropical tuna suggests a richer diet in this region than that of Indian Ocean tropical tuna and (or) differences in energy allocation strategies