NOT TO BE CITED WITHOUT PRIOR REFERENCE TO THE AUTHOR(S) Northwest Atlantic Fisheries Organization Serial No. N4716 NAFO SCR Doc. 02/95 SCIENTIFIC COUNCIL MEETING – SEPTEMBER 2002 Comparison of Elasmobranch Catches of Trawl Surveys and Commercial Landings of the Port of Viareggio (North Tyrrhenian-South Ligurian Sea-Italy) in the Last Decade (Elasmobranch Fisheries – Poster) by A. J. Abella and F. Serena Agenzia Regionale per la Protezione Ambientale della Toscana Via Marradi 114 57100 – Livorno Italy f.serena@arpat.toscana.it Abstract A catch assessment survey to monitor the landed elasmobranchs was enforced at the Viareggio harbour, the more important fishing port of the Tyrrhenian and Ligurian seas. Monthly data of catches by species and gear, size structure of the catches and spatial information on fishing effort distribution were collected over the period 1990- 2001. Data on catch rates and geographical distribution of species were also collected with trawl-surveys carried out each year in the same area in the period 1985-2001. For the most important chondrichthyan species, the distribution of the fishing effort for every main fishing strategy was compared with catch rates of trawl surveys. The analysed species were two batoids: Raja asterias and Raja clavata and two sharks: Scyliorhinus canicula and Galeus melastomus . The catch rates trends derived from fishery independent and fishery dependent sources resulted not in agreement probably due to spatial shifts in the effort allocation that occurred as a consequence of changes in the target of some fisheries. The current level of fishing pressure and fishing pattern seems sustainable for all the studied species. This can be related to a light fishing pressure on some grounds where certain species are concentrated, to the discard at sea of an important fraction of the individuals caught as well as to life history characteristics of each single species that make them more or less sensitive to enhancements in fishing mortality. Introduction The elasmobranchs are in general positioned at the top of the marine food webs and play an important role inside the ecosystems where they are present. The life history of elasmobranchs make them particularly vulnerable to fishing pressure. Their rarefaction as a consequence of removals that went beyond the sustainable levels has been stressed by many authors in several fisheries around the world (Stevens, et al ., 2000; Musick, et al ., 2000). There are some evidences that these phenomena have also occurred in the Northern Tyrrhenian-Ligurian Sea for Squalus sp ., Mustelus spp. and Squatina sp. (Vacchi et al ., 2000), even though quantitative information (such as long data series of captures) is incomplete. Since 1990, a monitoring programme is in force aimed at the collection of data on landings of chondrichthyan and bonefish in the main fishing harbours of the area. Furthermore, trawl-surveys utilising a traditional Italian trawl net have been also performed each year since 1985. Research cruises covers the whole area where the commercial fleets operate. The availability of these data allows seeking for changes in catch rates with time. Moreover, this go to Index