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