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Stable carbon and nitrogen isotope signatures have been determined for littoral fishes from three localities in the Balearic Islands (NW Mediterranean) for trophic assessment. Variation in the isotopic composition was examined at multiple levels: the individual organism, individual populations (ontogenetic variation) and at area effects (different islands). Cluster analyses based on d13C and d15N resulted in two very different dendrograms for the fish assemblages from Menorca and Formentera. In both schemes, congeners of the generaDiplodusandLabrusdid not cluster together, suggesting that closely related species do not necessarily feed on similar foods. Significant differences in d15N were detected between locations forScorpaena porcus, Scorpaena scrofaandSciaena umbra,and significant differences in d13C were detected forScorpaena porcusandScorpaena scrofa. Overall there were significant spatial differences in the trophic position of littoral fishes among the three Balearic Islands, and fishes from Palma, Mallorca tended to feed at a higher trophic level than fishes from either Menorca and Formentera. Large-scale geographic comparisons, using earlier data from three sites in western Mallorca and in Corsica revealed that throughout the western Mediterranean generally, the average trophic level of fishes differs remarkably little. However, large discrepancies were observed in d15N for individual species, notablyScorpaena porcus,D. annularis, D. vulgarisandSerranus scriba.13C composition of fishes did not seem to change greatly among the locations, although marked discrepancies were observed forD. puntazzoandMullus surmuletus. Given the large-scale patterns we have observed, it is possible that the extent of multichannel omnivory which has been purported to exist in complex aquatic systems, may have been greatly overstated. Regression of d15N and d13C with fish body size revealed clear and significant trends for some species. In particular, d15N appeared to increase with body length in the macrocarnivorous fishesScorpaena porcus, Scorpaena scrofa,Serranus scribaandSciaena umbra. Trends were less apparent in animals which feed primarily on small benthic invertebrates, notably the fourDiplodusspecies (D. vulgaris, D. sargus, D. annularis, D. puntazzo), and the labridsLabrus viridisandL. merula. [ABSTRACT FROM AUTHOR]

Abstract: In the NW Mediterranean Sea, anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) are the most important small pelagic fish in terms of biomass and commercial interest. Round sardinella (Sardinella aurita) and Sprat (Sprattus sprattus) are also present in this region. This paper provides a general insight into the ecology of these species through a revision of the information available in an environmental context and in relation to exploitation features. Spawning habitats of the two main species, anchovy and sardine, are clearly differentiated based on water mass characteristics reducing the overlapping between their early developmental stages. Larval distribution is also related to major productivity mechanisms of the respective spawning seasons. In spite of the different environmental regimes in which larvae of these species develop, growth rates are fairly similar. Trophic modeling highlights the important ecological role of small pelagic fish in North Western Mediterranean ecosystems. This review points out the gaps in knowledge necessary to understand the dynamics of small pelagic fish in the region and to progress towards a precautionary and adaptive management. [Copyright &y& Elsevier]

Abstract: In Europe, research to improve age estimation methods is often limited to small-scale studies and thus it has been difficult to integrate innovations into routine protocols. There has even been a lack of pilot scale studies and implementation of control mechanisms in the age reading process. This was recognised and addressed by European Fish Ageing Network (EFAN; 1997–2000). EFAN was established as an active, independent and informal network for exchange of ideas and experience for improving age estimation. For the first time, age reading problems were addressed on a common platform across Europe. EFAN improved awareness and sensitivity towards the quality of age reading, however, this did not always deliver changes in the routine age reading processes. The present project, Towards Accreditation and Certification of Age Determination of Aquatic Resources (TACADAR); 2002–2006 aims to submit a quality assurance manual including an evaluation of the legal aspects and implications to the European Union (EU). Through the network of excellence, TACADAR will strengthen the competitive position of European institutions involved in fish ageing through institutional synergy and international co-operation. [Copyright &y& Elsevier]