Short spatio-temporal variations in the population dynamics and biology of the deep-water rose shrimp Parapenaeus longirostris (Decapoda: Crustacea) in the western Mediterranean

The deep-water rose shrimp Parapenaeus longirostris is a demersal decapod crustacean that is commercially exploited by trawl fleets. The present work compares its population dynamics, biology and condition in two locations (southern and north-western Mallorca in the Balearic Islands, western Mediterranean, separated by a distance of 120 km) with different environmental conditions and explores the relationships between the species and certain environmental factors. Six multidisciplinary bimonthly surveys were carried out during 2003 and 2004 in these two locations (between 150 and 750 m depth) in order to collect data on the demersal species with bottom trawl, the hydrography (temperature and salinity) with CTD casts, and trophic resources (zooplankton in the water column and suprabenthos with Bongo net and Macer-GIROQ sledge respectively) and sediments with a Shipeck dredge. The trawl fleets from both locations were monitored by monthly on board sampling and daily landings obtained from sales bills. Additional data was obtained from other trawl surveys. Temporal differences were detected both annually, with a decreasing trend over the last years in species abundance, and seasonally, in the biological indexes analysed. Bathymetric differences were also found in abundance, mean length, sex-ratio and condition of females. There were clear differences between the two locations studied, with higher abundance, condition and mean length and a lower length at first maturity for females in the north-western location. Trophic conditions could act as a link between geo-physical and biological changes. These short spatio-temporal differences could be due to the higher productivity found at this location, with higher density of preferred prey for the studied species together with adequate seafloor topography, sediment composition and hydrographical characteristicsPublicado

Fish assemblages of an artificial reef in Posidonia oceanica (L.) Delile, 1813 meadow off the southern Balearic Islands (western Mediterranean)

The fish assemblage associated with an artificial reef composed of small blocks (12 m³) with high structural complexity set in a Posidonia oceanica (L) Delile, 1813 meadow has been studied for 2 years by means of visual censuses. The fish assemblage was dominated qualitatively by species with medium home ranges living; in the surrounding areas of the blocks (mainly Labridae species), and numerically by schooling mid water species. After 38 months of deployment the progressive colonisation of species living on the blocks and the surrounding areas was still ongoing. The colonisation process interacts with seasonal changes, and no clear variations in the fish community variables were observed. The type of block used and the situation of the reef seem inappropriate to the aims for which it was deployed.La evolución de la comunidad íctica de un arrecife artificial situado sobre pradera de Posidonia oceanica (L.) Delile, 1813 y formado por pequeños bloques (12 m³) de gran complejidad estructural se ha estudiado mediante censos visuales durante dos años. Cualitativamente la comunidad íctica está dominada por especies con desplazamientos medios que viven en las proximidades de los módulos (principalmente lábridos) y cuantitativamente por especies gregarias que se distribuyen en la columna de agua. A los 38 meses del fondeo del arrecife aun se observa la colonización de los bloques por especies que viven en sus proximidades o sobre los mismos. El proceso de colonización interacciona con las variaciones estacionales, no observándose una tendencia clara en los parámetros poblacionales. El tipo de módulo utilizado y la localización del arrecife no parecen ser apropiados para la consecución de los objetivos perseguidos en su inmersión.Instituto Español de Oceanografí

Evaluación preliminar de los desembarques y descartes de la pesquería de arrastre de fondo de Turquía en el mar Egeo nororiental (Mediterráneo oriental)

This short-term study on commercial discards was carried out in fishing grounds around Gökçeada Island in the northeastern Aegean Sea, a geographic area where fisheries information is rather limited. A total of 28 bottom trawls were performed between 70 and 410 m depth from December 2009 to February 2010. All the samples were collected on board a commercial trawler under commercial fishing conditions. A total of 3143 kg of biomass was caught in 28 valid hauls. Landings accounted for about 67% of the total catch while the remaining 33% was discarded. Fish species comprised 85% of the total catch and their composition could be divided into four main groups related to depth: shallow shelf (70 to 88 m), deep shelf (155 to 180 m), shelf break (196 to 276 m), and upper slope (307 to 410 m). Fish dominated the abundance and biomass of both landings and discards in all bathymetric strata. Echinoderms also accounted for a large proportion of the discards. Mean total catches varied between 78.4 kg/h on the shallow shelf and 38.1 kg/h on the shelf break with no differences in the landing biomass between groups, but with slightly higher discards over the shallow shelf. Taking into account the preliminary nature of the findings, based on a short-term analysis, the minimum mesh size and minimum landing size currently applied in the Turkish bottom trawl fishery are not sufficient to reduce discards and to protect juveniles of commercially important species in the northeastern Aegean Sea.Este estudio a corto plazo sobre los descartes de la flota comercial de arrastre se llevó a cabo en las zonas de pesca alrededor de la isla Gökçeada en el noreste del mar Egeo, una zona geográfica en la que la información sobre las pesquerías es bastante limitada. Se realizaron un total de 28 pescas de arrastre de fondo entre 70 y 410 m de profundidad de diciembre 2009 a febrero de 2010. Todas las muestras se recogieron a bordo de un embarcación de pesca de arrastre siguiendo las mismas condiciones de pesca comercial. Se capturaron un total de 3143 kg de biomasa en 28 lances válidos. Los desembarques comerciales representaron alrededor del 67% de la captura total, mientras que el resto (33%) se descartó. El 85% de la captura total estuvo compuesta por especies de peces. La composición específica se pudo separar en cuatro grupos principales relacionados con la profundidad : la plataforma poco profunda (70 a 88 m), la plataforma profunda (155-180 m), el borde inferior de la plataforma (196 a 276 m) y el talud superior (307-410 m). Los peces dominaron la abundancia y biomasa tanto de los desembarques comerciales como de los descartes en todos los estratos batimétricos. Además los equinodermos también fueron un grupo importante de los descartes. La media de las capturas totales varió entre 78.4 kg/h en la plataforma poco profunda y 38.1 kg/h en el borde de la plataforma, sin diferencias en la biomasa desembarcada entre los dos grupos, pero siendo los descartes ligeramente superiores en la plataforma poco profunda. Teniendo en cuenta el carácter preliminar de los resultados, obtenidos sobre la base de un análisis a corto plazo, el tamaño mínimo de malla de la red y la talla mínima de las especies comerciales aplicada hoy en día en la pesquería de arrastre de fondo de Turquía no son suficientes para reducir los descartes y proteger a los juveniles de las especies de importancia comercial en el Mar Egeo nororiental

Feeding ecology of demersal elasmobranchs from the shelf and slope off the Balearic Sea (western Mediterranean)

The feeding ecology of eight demersal elasmobranchs, three sharks (Etmopterus spinax, Scyliorhinus canicula and Galeus melastomus) and five batoids (Myliobatis aquila, Leucoraja naevus, Raja polystigma, R. miraletus and R. clavata), from the Balearic Sea (western Mediterranean) was analyzed. For each species, the diet and feeding habits were characterized by depth strata using quantitative indices such as diet overlap, diet breadth and prey diversity. Diet variation with size and depth were also tested for the most abundant species. For shelf-living species, natantian and reptantian crustaceans together with teleosts were the most important preys. On slope bottoms, euphausiids were the preferential prey for S. canicula and G. melastomus, while E. spinax fed mainly on cephalopods. The most specialist and generalist diet corresponded to G. melastomus living on the upper slope and S. canicula from the continental shelf, respectively. High overlap was found between all the skates on the continental shelf and the sympatric sharks S. canicula and G. melastomus on the slope. Significant overlap was also found between S. canicula and R. clavata on the continental shelf. Size was found to significantly affect the diet of S. canicula, G. melastomus and R. clavata, whereas depth affected exclusively S. caniculaPublicado

Dades sobre la capture de dues espècies del gènere Tetrapturus (Osteichthyes, Istiophoridae) al mar Balear (Mediterrània occidental)

Abstract not availabl

Antoni Llompart Rexach (1897-1990)

Abstract not availabl

Stock assessment of Mullus surmuletus from GFCM GSA-05 (Balearic Islands)

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