Occurrence and abundance of the deep-water red shrimps Aristeus antennatus (Risso, 1816) and Aristaeomorpha foliacea (Risso, 1827) in the Mediterranenan Sea

The blue and red shrimp Aristeus antennatus and the giant red shrimp Aristaeomorpha foliacea are among the major economic resources in the Mediterranean Sea and represent the main target of the western and central Mediterranean deep sea (400 800 m) fisheries. In this paper, data on abundance (both number and biomass) of A. antennatus and A. foliacea resulting from the MEDITS surveys from 1994 to 2004, carried out with common protocols in seven Mediterranean FAO GFCM Geographical Sub Areas (GSAs), have been analyzed using standardized methodologies. Both red shrimps species occur almost exclusively on the “meso bathyal” stratum (500 800 m). The distribution pattern appears quite different for the two species, but no significant trends in density and biomass (neither at geographical nor at temporal level) could be detected. Sardinia shows the highest abundance for both species, although with some local negative tendencies along time. A very high interannual variability was detected in all areas. Comparing the present results to those recorded by Cau et al. in 2002, a more or less stable status of the deep sea red shrimps stocks was observed, which is not an encouraging finding when considering the reduction in fishing capacity and the management measures adopted by the EU in recent years

Biological patterns and ecological indicators for Mediterranean fish and crustaceans below 1,000 m: a review

19 páginas, 3 figuras, 6 tablasThe Mediterranean Sea is a relatively deep, closed sea with high rates of fisheries exploitation. In recent years fishing activity has tended to shift towards deeper depths. At the same time, the Mediterranean displays some rather special hydrographic and biogeographic conditions. The present paper reviews the present state of knowledge of the fisheries, biology, and ecology of the deep-sea fish and crustacean species in the Mediterranean dwelling below 1,000 m with potential economic interest, placing special emphasis on the western basin, for which more data are available, as a basis for future studies of the ecology, biodiversity, and effects of climate change and exploitation in this zone. This review reveals that mediterranean deep-sea fishes and crustaceans employ highly conservative ecological strategies, and hence the low fecundity and low metabolic rates in a stable environment like the deep-sea make these populations highly vulnerable. Moreover, ripe females of the main species mentioned here concentrate in the deepest portions of their distribution ranges. Deep-sea fish and crustaceans have high trophic levels and low to medium omnivory index values. The ecological indices discussed here, in combination with the limited knowledge of deep-sea ecosystems, clearly call for an approach based on the Precautionary PrincipleThe authors would like to thank the Captains and crews of R/V ‘‘García del Cid’’ (CSIC) for their technical support, and Mr. J. Rucabado and Dr. D. Lloris as the pioneers in using the otter bottom trawl as a sampling scientific method in the Mediterranean deep-sea. M. Coll has been founded by a postdoctoral fellowship from the Ministerio de Ciencias e Innovación from SpainPeer reviewe

The foraging ecology of larval and juvenile fishes

Knowledge of the foraging ecology of fishes is fundamental both to understanding the processes that function at the individual, population and community levels, and for the management and conservation of their populations and habitats. Furthermore, the factors that influence the acquisition and assimilation of food can have significant consequences for the condition, growth, survival and recruitment of fishes. The majority of marine and freshwater fish species are planktivorous at the onset of exogenous nutrition and have a limited ability to detect, capture, ingest and digest prey. Improvements in vision, development of fins and associated improvements in swimming performance, increases in gape size and development of the alimentary tract during ontogeny often lead to shifts in diet composition. Prey size, morphology, behaviour and abundance can all influence the prey selection of larval and juvenile fishes. Differences in feeding behaviour between fish species, individuals or during ontogeny can also be important, as can inter- and intraspecific interactions (competition, predation risk). Temporal (diel, seasonal, annual) and spatial (microhabitat, mesohabitat, macrohabitat, regional) variations in prey availability can have important implications for the prey selection, diet composition, growth, survival, condition and, ultimately, recruitment success of fishes. For fish populations to persist, habitat must be available in sufficient quality and quantity for the range of activities undertaken during all periods of development. Habitats that enhance the diversity, size ranges and abundance of zooplankton should ensure that sufficient food resources are available to larval and juvenile fishes