Age and growth of the ommastrephid squid Todarodes sagittatus from the western Mediterranean Sea

Age and growth of Todarodes sagittatus were estimated based on statolith analysis from individuals (N=352; 81-418 mm mantle length) caught by bottom trawlers during a year of sampling in the western Mediterranean. The daily nature of statolith increments was indirectly validated comparing the mean age of consecutive monthly modes (identified on the monthly length-frequency distributions) with the corresponding increase of 30 days. In agreement with other ommastrephids, results confirmed the following points: (1) lifespan lasts nearly a year; (2) growth rates decrease with age; (3) when adult, females have higher growth rates than males; and (4) females mature about a month later than males. Significant correlation was found between hatching (which occurred throughout the year but with a peak in November) and temperature at 50 m depth (where it is thought that hatchlings inhabit). Age and growth results were compared with those obtained in a similar work carried out in north-west Africa (Arkhipkin et al., 1999). Comparisons suggested that due to higher growth rates in juveniles, southern populations reach maturity and consequently decrease somatic growth at younger ages and smaller sizes than northern squid, which attain larger sizes as a result of maintaining fast growth and delaying maturation. Greater growth rates in juveniles from west Sahara could be explained by higher temperatures in this area than in the Mediterranean.Peer Reviewe

Objetivos clave de las Ciencias Marinas Españolas en el contexto europeo (2003-2007)

[EN] The analysis of the marine projects funded by the Spanish RTD funding agency between 2003 and 2007 in the framework of the European policies, showed that although the funds available have increased (232 projects and 33 Million € from 2003 to 2007) there are still research and strategic areas that are not covered. The relevance of marine related services and economic revenues for Spain requires that a strategy is developed to address the challenges that are emerging due to the growing competing uses of the sea, which include maritime transport, fishing, aquaculture, leisure activities, off-shore energy production and other forms of seabed exploitation. By helping to develop a more sophisticated understanding of the impact of human activities on marine systems, scientific research and technology may provide the key to carrying out seabased activities without degrading the environment, and to predicting and mitigating as far as possible the effects of climate change.[ES] Dentro del marco de las políticas europeas, el análisis de los proyectos sobre el medio marino sufragados por la Agencia Española de Investigación, Desarrollo e Innovación (I+D+I) durante los años 2003-2007 pone de manifiesto que, aunque se han incrementado las subvenciones concedidas (232 proyectos y 33 millones de euros en dicho período), existen todavía sin cubrir determinadas áreas estratégicas y de investigación. La relevancia para España de los servicios e ingresos económicos relacionados con el medio marino requiere que se desarrolle una estrategia que dirija los desafíos resultantes de la creciente competencia de usos que el mar genera, tanto desde el punto de vista del transporte marítimo, la pesca, la acuicultura, el ocio, la producción de energía en mar abierto, como de otras formas de explotación del fondo marino. Para ayudar a desarrollar una mejor y más sofisticada comprensión del impacto de las actividades humanas sobre los sistemas marinos, la investigación científica y la tecnología deben ser capaces de proporcionar las claves necesarias para desacoplar de la degradación ambiental las actividades de explotación relacionadas con el mar, de modo que se predigan y atenúen tanto como sea posible los efectos del cambio climático.Peer reviewe

Distribució i abundància de Symphurus nigrescens Rafinesque, 1810 i Symphurus ligulatus (Cocco, 1844) (Pisces, Pleuronectiformes) en el talús del mar Català

Abstract not availabl

Fishery and growth of Aphia minuta off Majorca island

Publicado

Life cycle of the pelagic goby Aphia minuta (Pisces: Gobiidae)

Reproductive aspects of the transparent goby Aphia minuta (n=2977, 14-45 mm total length (TL)) were studied in Majorcan waters, western Mediterranean, during the fishing season (December to April) from 1985 to 1993. Male:female sex ratio was 1:1. Size at first maturity was 38 mm TL for females and 34 mm TL for males. Oocyte size-frequency distribution indicated that A. minuta is a single spawner. Fecundity of A. minuta ranged from 935 to 2648 oocytes. The breeding season extended from December to April with a peak in March. After a single reproduction at 5-6 months of age, most of the specimens disappeared from the fishing areas. Recruitment to the fishing area occurred in late December and early January (14-24 mm TL, age 2-3 months). On the other hand, the hatch date back-calculated from the age in days and the date of capture of individuals of A. minuta during the fishing season, indicated a spawning peak in autumn (September-October), six months after the peak of observed spawning. Schools of A. minuta were detected by acoustic methods, during the fishing season (winter-spring) in fishing areas (5-40 m depth), principally inside bays, and during the rest of the year (summer and autumn) in deeper areas (40-90 m), outside bays, with water temperatures between 13 and 16ºC and a high seasonal productivity in each depth range. Therefore, we propose that A. minuta has two annual cohorts in the western Mediterranean, corresponding to two main spawning in spring and autumn, respectively. Life history pattern indicated that we only know the winter cohort resulting from the autumn spawning. Meanwhile the summer cohort (spring spawning) grows and reproduces in deeper areas not being targeted by the fishery. Indirect validation is provided from information from other areas. The relevance of the life cycle is discussed in relation to fishery managementPublicado

Specific Merluccius otolith growth patterns related to phylogenetics and environmental factors

5 pages, 2 figures, 2tablesA comparative morphological study was performed on the otolith growth patterns of 11 species of the genus Merluccius. The otolith growth pattern, based on the radius of the first eight growth increments (GI) from the otolith core, was determined from transverse sections of sagitta otoliths. The structure and periodicity of the GI were identified based on previous knowledge. Two cluster analyses were performed using GI width as a proxy for otolith growth. The first cluster analysis corresponded to the juvenile (immature) period of the ¢sh including the mean width of the first four GI. The second analysis compared the mean width of the next four GI, i.e. those corresponding to mature fish. The results showed an important environmental influence in immature fish; while after maturation, the GI pattern was also related to an endogenous influence depending on the phylogenetic line.This work was supported by the EU FAIR project CT 95-0655. Gabriel Torres’s contribution was funded under the doctoral fellowship grant provided by the Spanish International Co-operation Agency (AECI) and the Latin-American-Catalonian Co-operation Institute (ICCI).Peer reviewe

Estimation et analyse bio-économique d'une pêche au trémail de l'île de Majorque (NO Méditerranée)

9 pages, 9 figures, 6 tables.[EN] Trammel net is the main fishing gear used by artisanal fishers in Majorca Island (NW Mediterranean), and is representative of Mediterranean small-scale fisheries using static gear. The use of static gears close to the coast, where seasonal variability and spatial heterogeneity are high, promotes the diversification of fishing practices or metiers. We analyze the seasonal dynamics of the nets used, target species (red and black scorpionfish, red mullet and cuttlefish) exploitation patterns and the socio-economic conditions under which this fishery takes place, based on General Fisheries Directorate daily sale records (2002-2006). Additional personal socioeconomic interviews allowed the characterization of the trammel net fishery, its fishing behaviour, cost structure and conflicts. Catch and effort data and market surveys are used to evaluate the level of exploitation of the target species and allowed describing Majorca trammel net fishery as an activity based on a sustainable resource. The main target species were found to be near their maximum sustainable yield both by means of a surplus production model (with parameters estimated by CEDA-Catch Effort Data Analysis, software) and an age structured assessment model based on yield-per-recruit analysis. Management actions currently debated by local administration and fishers focus on improving fishers' economic situation, rather than on protecting a threatened resource. One of the management actions proposed is a one day effort reduction, which was analyzed here with the help of a bioeconomic simulation model. A 15-year (2005-2020) simulation allows providing advice to local managers to focus on the commercialization aspects, in order to obtain a higher value to the fish production, rather than expecting to obtain higher profits only by a reduction of the offer.[FR] Le filet trémail est le principal engin de la pêche artisanale utilisé par les pêcheurs de l'île de Majorque (NO Méditerranée) ; il est représentatif de la petite pêche en Méditerranée, utilisant des engins dormants. L'usage de ces engins dormants à proximité de la côte, où la variabilité saisonnière et l'hétérogénéité spatiale sont élevées, entraîne la diversification des pratiques de pêche ou métiers. Nous analysons la dynamique saisonnière des filets utilisés, les espèces-cibles (rascasse rouge, rascasse blanche, le mulet barbet et la seiche), les modèles d'exploitation et les conditions socio-économiques sous lesquelles la pêcherie se développe, basées sur les données des ventes journalières de la Direction Générale des Pêches (2002-2006). Des enquêtes socio-économiques ont permis de caractériser la pêcherie au trémail, les comportements de pêche, la structure des coûts et les conflits. Les données d'effort et de capture et l'étude du marché sont utilisées pour évaluer le niveau d'exploitation des espèces-cibles et permettent de décrire la pêcherie au trémail de Majorque comme une activité basée sur des ressources à l'équilibre. Les principales espèces-cibles sont trouvées proches de leur rendement maximum à l'équilibre, à la fois au moyen d'un modèle de surplus de production (avec des paramètres estimés au moyen du logiciel CEDA, Catch Effort Data Analysis) et par un modèle d'estimation structurée en âge, basé sur l'analyse des rendements par recrue. La gestion couramment débattue par l'administration locale et les pêcheurs se focalisait sur l'amélioration de la situation économique des pêcheurs plutôt que de protéger une ressource en danger. Une des actions de gestion proposée est une réduction de l'effort - un jour de pêche, qui peut être analysée ici avec l'aide d'un modèle de simulation bio-économique. Une simulation sur 15 ans (2005-2020) permet de fournir des conseils aux gestionnaires locaux sur les aspects de commercialisation, en vue d'obtenir une plus haute valeur de production de poissons, plutôt que d'espérer obtenir des profits plus élevés par une réduction de l'offre seulement.This study was funded by the Commission of the European Communities, specific RTD programme “Specific Support to Policies”, SSP-2004-22745 “Probabilistic assessment, management and advice model for fishery management in the case of poor data availability” (POORFISH).Peer reviewe