Feeding of Greenland Halibut (Reinhardtius hippoglossoides) in 3LMNO NAFO Regulatory Area Divisions (Northwest Atlantic), 1991-94

Feeding of Greenland halibut in Flemish Pass and Newfoundland's Grand Bank slope (3LMNO NAFO divisions) was studied from on board commercial fleet analysis, from June 1991 to December 1994. Percentage of empty stomachs from 625 165 specimens and frequency of occurrence of prey from 18 527 stomachs, were used to evaluate feeding intensity and importance of prey groups. Examinationrevealed increasing feeding intensity with sin. The emptiness percentage varies with depth, in a directly proportional way, in specimens of less than 60 cm, and is inversely proportional in those of over 70 cm. A smaller percentage of empty stomachs was found in females than in males, upwards of the length of first maturity of the latter, as well as a decreasing feeding rate as females become reproductively active. Analysis of frequency of occurrence of main prey groups indicated a change in Greenland halibut feeding at 60 cm in all divisions, a change which supposes a fall in consumption of 0161w:elms and molluscs, an increase in fish and (fiat and an increase in prey species size. the difference between divisions is due to the consumption of Mallows yillosus by specimens of less than 60 cm in divisions 3NO : There are also significant changes with depth of around 1000 m in the diet of Reinhard/ins hippoglossoides of less than 60 cm, bringing about a substitution of capelin for decapod cephalopods At great depths squid have a similar role in the diet of Greenland halibut to that played by capelin on the continental shell The variation of the prey species is related to their disnibution. Offal arc an extra provision of food introduced by fishing activity, making up the second most important prey group in specimens of over 60 cm

Length Distributions and Recruitment Index of Northern Shrimp (Pandalus borealis) in Flemish Cap (Division 3M) in 1993-1998, as Inferred from Stomach Contents Analysis of Cod (Gadus morhua), Greenland halibut (Reinhardtius hippoglossoides) and Thorny Skate (Raja radiata)

From stomachs of cod (Gadus morhua), Greenland halibut (Reinhardtius hippoglossoides) and thorny skate (Raja radiata) sampled in the fishing surveys carried out in Flemish Cap in July from 1993 to 1998, the importance in diet, predator-prey relationship and length frequency of northern shrimp (Pandalus borealis) were evaluated. These three species prey on different lengths of northern shrimp as a function of their feeding habits and the overlap in their ranges of vertical distribution with that of their prey. The ability of these predators to sample different sizes of northern shrimp allows the observation of the annual progression of strong year classes of this prey and the estimate of its recruitment at age 2 from its frequency of occurrence in cod stomach contents from 1989 to 1997

Feeding Patterns of Greenland halibut (Reinhardtius hippoglossoides) in Flemish Pass (Northwest Atlantic)

A qualitative study of the food composition of Greenland halibut (Reinhardtius hippoglossoides) was made by on-board analysis of commercially caught fish in 1992. The fish were caught east of Newfoundland (NAFO Div. 3LM) in unusually deep waters, with an average of 1 040 m. Variations in feeding according to predator size, depth and month were studied. The annual average percentage of empty stomachs was 69%, increasing through the year for specimens over 60 cm. The frequency of occurrence (FO) of food items was used to evaluate the importance of prey groups. Fish (39%), cephalopods (32%) and decapod crustaceans (22%) were the main items, with cannibalism reaching 2%. An abrupt change in diet composition occurred in fish between 60 and 69 cm, from feeding on decapod crustaceans and cephalopods to fish and factory ship discarded offal. The influence of the fishery itself on the diet of Greenland halibut was observed when an important food component in the largest specimens (>60 cm) consisted of offal discarded after fish processing. This study indicates that the FO of the main prey groups bears more relation to the size of fish than with depth

Feeding of Most Abundant Fish Species in Flemish Cap in Summer 1993

The stomach contents of 4320 fishes comprising 14 species were collected from Flemish Cap Bank (NW Newfoundland) at depths ranging from 130 to 730 m, during summer 1993. The general feeding intensity was high in all species. Three main feeding patterns were evident: the genus Sebastes consume primarily pelagic species, although they also feed on preys which migrate vertically such as shrimps, Euphausids and mysids. The benthic group is made up of American plaice (Hippoglossoides platessoides), witch flounder (Glyptocephalus cygnoglossus), arctic eelpout (Lycodes reticulatus), wolffishes (Anarhichas lupus and Anarhichas minor) and thorny skate (Raja radiata). Lastly, the group of benthopelagic fish remains, longf in hake (Urophycis chesteri), cod (Gadus morhua), grenadiers (Nezumia bairdi and Macrourus berglax) and Greenland halibut (Reinhardtius hippoglossoides). Pelagic and benthopelagic preys are an important food resource for all fish considered, the abundance of Hyperids, P. borealis and Sebastes sp. in summer makes them an important food resource in the diet of fish in Flemish Cap

Tracking bluefin tuna cohorts from east Atlantic Spanish fisheries since the 1980s

Relative abundance and mean size at age analyses were performed for the catches of three Atlantic Spanish fisheries, in search of an exceptionally abundant cohort in the recent history of the eastern Atlantic and Mediterranean bluefin tuna stock. Length distributions of baitboat fisheries, both in the Bay of Biscay and areas close to the Strait of Gibraltar as well as trap catches from the Spanish Atlantic coast were converted to age distributions using age length keys from calcified structures. Results do validate indirectly the ageing method. The 1994 cohort was clearly tracked for juveniles and young adults, 3 to 7 years old, in baitboat catches, and also for older specimens, 9 to 11 years old, in the trap fisheries. Based on these results, it is suggested that the juvenile and young adults fisheries in the western part of the Iberian Peninsula are interconnected between one another and with the Balearic Islands area of the western Mediterranean, as it is the nearest spawning ground described and because it is also supported by tagging and other studies.Afin de trouver une cohorte exceptionnellement abondante dans la récente histoire du stock de ton rouge de l’Atlantique Est et de la Méditerranée, on a procédé à une analyse de l’abondance relative et de la taille moyenne par âge des captures réalisées par trois pêcheries espagnoles de l’Atlantique. Les distributions par tailles de deux pêcheries de canneurs dans le Golfe de Gascogne et dans les eaux proches du Détroit de Gibraltar, ainsi que les prises des madragues de la côte atlantique espagnole, ont été converties en âges à l’aide des clefs taille-âge obtenues à partir de la lecture de structures calcifiées. Les résultats valident indirectement la méthode de détermination de l’âge. La cohorte de 1994 affiche une forte indication présente chez les juvéniles et les jeunes adultes, de 3 à 7 ans, capturés dans les pêcheries de canneurs ainsi que chez les spécimens d’âge plus avancé, de 9 à 11 ans, pêchés à la madrague. Ces résultats suggèrent que les pêcheries de juvéniles et de jeunes adultes de la partie occidentale de la péninsule ibérique sont interconnectées entre elles ainsi qu’avec la zone des îles Baléares, en Méditerranée occidentale, étant donné qu’il s’agit de la zone de frai la plus proche et qu’il existe des indices de cette relation d’après les études de marquage et d’autres études.Para encontrar una cohorte excepcionalmente abundante en la historia reciente del stock de atún rojo del Atlántico este y Mediterráneo, se realizó un análisis de la abundancia relativa y la talla media por edad de las capturas de tres pesquerías atlánticas españolas. Las distribuciones de tallas de dos pesquerías de cebo vivo, en el Golfo de Vizcaya y en aguas próximas al Estrecho de Gibraltar, así como las capturas de las almadrabas de la costa atlántica española, fueron convertidas a edades mediante el uso de claves talla edad, obtenidas a partir de la lectura de piezas esqueléticas. Los resultados validan indirectamente el método de determinación de la edad. La cohorte de 1994 presenta una fuerte señal que pudo ser encontrada en los juveniles y adultos jóvenes, 3 a 7 años, capturados en las pesquerías de cebo vivo y también en especimenes mayores, 9 a 11 años, pescados con las almadrabas. Con esto resultados se sugiere que las pesquerías de juveniles y adultos jóvenes de la parte occidental de la península Ibérica están interconectadas entre ellas y con el área de las Islas Baleares, en el Mediterráneo occidental, puesto que es la zona de puesta más próxima y porque también hay evidencias de esta relación mediante el marcado y otros estudios

An approach to age and growth of south Atlantic swordfish (Xiphias gladius) stock

A first growth function was estimated for the South Atlantic swordfish stock. A total of 406 anal fins were collected from 2006 to 2013. Fins were classified into three types and the most common, type A, was selected. Biometric relationships among several ray section measurements and lower jaw fork length were analysed. A detailed methodological description for swordfish age interpretation has been developed. Inconclusive results have been obtained when indirect validation test, as edge type and marginal increment ratio analysis, were applied. Mean size at age and growth parameters were estimated using the Standard Von Bertalanffy growth model (VBGM) (L∞= 358.7, k= 0.092, t0= -1.929), which showed the best fit in comparison with other VBGMs

Bluefin tuna (Thunnus thynnus) tagging survey in the Bay of Biscay in summer 2005

A brief summary of the conventional tagging survey carried out during the summer fishing season in 2005 in the Bay of Biscay is presented. A total of 1696 juveniles of bluefin tuna have been tagged, corresponding to group ages 1 and 2. Two different conventional tags have been used. Fifty-one recaptures have been recovered up to date.Le présent document fournit un résumé de la campagne de marquage conventionnel de thon rouge menée au cours de l’été 2005 dans le Golfe de Gascogne. Au total, 1.696 juvéniles de thon rouge ont été marqués, correspondant aux groupes d’âge 1 et 2. Deux types distincts de marques conventionnelles ont été utilisés. Cinquante-et-une marques ont été récupérées à ce jour.Se presenta un resumen de la campaña de marcado convencional de atún rojo llevada a cabo durante el verano del 2005 en el Golfo de Vizcaya. En total se han marcado 1696 ejemplares de 1 y 2 años de edad. Se han utilizado dos modelos distintos de marcas convencionales. Hasta la fecha se han recapturado cincuenta y un ejemplares

Report of the 2006 ICCAT workshop for bluefin tuna direct ageing

This report provides the presentations, discussions and conclusions from the ICCAT bluefin tuna workshop for direct ageing held in Santander, Spain, in April 2006. The report summarizes the ageing criteria used in the past and the agreements on future age determination based on otoliths, vertebrae and spines. Advantages and disadvantages of each calcified structure for ageing and border interpretation were discussed. It was considered that bluefin tuna age interpretation becomes very difficult from age ten onwards using the whole vertebra and the spine sections methods, but this last technique continues to be useful for older ages. Otolith sections can be used for the whole age range. Participants agreed that none of these three structures could be excluded from routine ageing because otoliths are not easily available. Age estimations within the same structure and between different structures of the same specimen were compared for several readers. Better precision was found between spine readers compared to vertebra and otolith readers. Good age agreement was also achieved between readers of spines and vertebrae from the same bluefin for ages less than 12 years. Preliminary results from radiocarbon assays on otoliths were presented at the workshop and gave promising outcomes for bluefin tuna age validation. Also, these suggested that bluefin tuna can live longer than had previously been established and that a review is needed of the currently used asymptotic size and growth rate for both stocks. Another important contribution of the workshop was a manual for age interpretation.Le présent rapport recueille les présentations, discussions et conclusions de l’Atelier de l’ICCAT chargé de la détermination directe de l’âge du thon rouge, tenu à Santander (Espagne) au mois d’avril 2006. Le rapport résume les critères employés par le passé pour interpréter l’âge et les accords pour la détermination future de l’âge à partir des otolithes, vertèbres et épines. L’Atelier a discuté des avantages et des inconvénients de chaque structure calcifiée pour déterminer l’âge et l’interprétation du type de bord. On a abordé la difficulté de l’interprétation de l’âge des thons de plus de 10 ans au moyen de la vertèbre entière et des sections des épines, bien que cette dernière méthode continue d’être utile pour les âges avancés. Les sections d’otolithes peuvent être employées pour toute la gamme d’âges. Les participants ont convenu qu’aucune de ces trois structures ne doit être exclue pour l’interprétation de l’âge parce qu’il n’est pas toujours possible d’obtenir des otolithes. On a comparé les lectures de l’âge à l’intérieur de la même structure et entre différentes structures du même exemplaire pour divers lecteurs. On a obtenu une plus grande précision parmi les lecteurs d’épines que parmi les lecteurs de vertèbres et d’otolithes. On a également obtenu un bon accord entre les lecteurs d’épines et de vertèbres originaires du même exemplaire pour les âges inférieurs à 12 ans. Les résultats préliminaires des essais de radiocarbone dans les otolithes ont été présentés à l’Atelier, offrant de bonnes perspectives pour son utilisation dans la validation de l’âge. Ces résultats indiquent aussi que le thon rouge a une plus grande longévité que ce qui avait été auparavant établi et qu’il est nécessaire de réviser la longueur asymptotique et le taux de croissance actuellement utilisés. L’élaboration d’un manuel aux fins de l’interprétation de l’âge a constitué une autre contribution importante de l’Atelier.Este informe recoge las presentaciones, discusiones y conclusiones del congreso de ICCAT para la determinación directa de la edad de atún rojo, celebrado en Santander, España, en abril de 2006. El informe resume los criterios empleados en el pasado para interpretar la edad y los acuerdos para la determinación futura de la edad a partir de otolitos, vértebras y espinas. Se discutieron las ventajas y los inconvenientes de cada estructura calcificada para determinar la edad y la interpretación del tipo borde. Se planteó la dificultad en la interpretación de la edad de atunes mayores de 10 años utilizando la vértebra entera y las secciones de espinas, no obstante este último método continúa siendo útil para edades mayores. Las secciones de otolitos pueden ser empleadas para todo el rango de edades. Los participantes acordaron que ninguna de estas tres estructuras deben excluirse para la interpretación de la edad porque no siempre es posible obtener los otolitos. Se compararon las lecturas de edad dentro de la misma estructura y entre diferentes estructuras del mismo ejemplar para varios lectores. Se obtuvo una mayor precisión entre lectores de espinas comparada con las obtenidas por los lectores de vértebras y otolitos. También se obtuvo un buen acuerdo entre lectores de espinas y vértebras procedentes del mismo ejemplar para edades menores de 12 años. Los resultados preliminares de las pruebas de radiocarbono en otolitos fueron presentados en el congreso, proporcionando buenas expectativas para su uso en la validación de la edad. Estos resultados también indican que el atún rojo es más longevo de lo que se consideraba y que es necesaria una revisión de la longitud asintótica y de la tasa de crecimiento empleadas actualmente. Otra importante contribución del congreso fue la elaboración de un manual para la interpretación de la edad