1. 1)CTS – Settore Conservazione Natura, Via Andrea Vesalio 6, 00161 Roma, Italy 2)Università degli Studi di Torino, Via Accademia Albertina 13, 10123 Torino, Italy FISHERIES CATCH AND BOTTLENOSE DOLPHIN ABSENCE/PRESENCE AROUND LAMPEDUSA ISLAND (SICILY – ITALY) LIFE 2003 NAT/IT/000163 PROVINCIA REGIONALE DI AGRIGENTO Università di Torino promosso da partner Celoni F. 1, Azzolin M. 2, Galante I. 1, Comparetto G. 1, Giacoma C. 2 Introduction Starting from 2003, in the framework of the LIFE project NAT/IT/000163, a dolphin-fishery interaction study has been conducted in the Archipelago of Pelagie Islands (South of Sicily, Italy, Fig.1). The local fishery fleet consists of 164 total fishing licences, 95 for fishing lines, 30 for gill nets, 29 for trawl net and 10 for fish trap. In addition to the local fleet, also the boats belonging to the Sicilian and North African fleet are usually fishing in the Archipelago area. Those last boats are mainly using trawling nets or surrounding nets. Due to that, the total fishing effort for the area is not so easy to quantify. Following a series of interview with fishermen, the interaction study has been focused on gill net, the gear for which fishermen were complaining frequent negative dolphin’s interaction in 83% of the cases. Frequent interaction was complained also by 72% of long line fishermen and 100% of trawler but with a lower economic impact. Material and methods Between May 2004 and February 2006 the interaction of bottlenose dolphin with fishing activities was monitored by researcher directly boarded on 4 different fishing boats equipped with 55-mm mesh gill nets (Tab.1). During navigation and fishing activity data were regularly collected on: weather condition, position of the fishing gear (coordinates and depth) (Fig.2), time of the day of net’s setting and hauling, dolphin’s presence and number. In case of dolphins sighting, behavioral data were also collected, in order to highlight positive or negative interaction among dolphin and fishery gears. Back in the harbour the landed fishes were monitored: weight and length measures were taken for each caught species. Notes were also taken on damaged fishes. Fig.1 - Bathymetry of the Sicily Channel and location of Pelagie Islands. Tab.1 - Boat’s description and net’s dimension Results Between May 2004 and February 2006, 28 surveys have been carried out, preliminary results are presented. The target species caught during the surveyed period depended on the season, M. maena mainly in spring (May-June) and M. surmuletus in winter (December-April). Nevertheless, while when fishing for M. maena few other species were caught, when fishing for M. surmuletus many other species were taken, particularly: Boops boops, Maena maena, Pagellus erythrinus, Spondyliosoma cantharus, Diplodus annularis, Diplodus vulgaris, Dentex dentex, Crenilabrus tinca, Serranus scriba, Scorpaena scrofa, Scarus cretense. The analysis of dolphin’s presence during fishing activities shows that: dolphins were present in 35,7% of the total surveys and absent in the 64,3% of the case. Considering separately surveys for M. maena and surveys for M. surmuletus dolphins were respectively present in 70% and 19% of the cases and absent in 16,7% and 83,3% of the cases (Tab.2). the number of dolphins sighted close to the net ranged from a minimum of 2 up to a maximum of 11 animals, with a mean group size of 4,6 animals. Considering separately surveys for Maena m. and surveys for Mullus s. the mean group size is respectively of 5,6 and 2,3 animals (Tab.3). In order to compare data from landed fishes of different surveys, value on kg over square meter has been used (Tab.4 and Fig.3,4,5). The analysis of damaged landed fishes shows that: fishes damaged by dolphins were present in 17,8% of total surveys, and in 50% of the surveys with dolphins. The damaged fish species were: Diplodus vulgaris, Diplodus annularis, Boops boops, M. surmuletus, M. maena. The damages consisted of cut off fishes. A mean of 0,00197 of damaged fishes/sq.m was obtained from monitoring; fishes damaged by other predators were present in 14,28% of total surveys, in 22% of surveys without dolphins. A mean of 0,00021 of damaged fishes/sq.m was obtained from analysis. Tab.3 - Mean group size Tab.2 - Surveys without/with dolphins Fig.2 – Surveys’s way point Tab.4 – Kg/square meter of net Fig.3 – Analysis of the mean for fishery catches without and with dolphins shows a reduction from 0,04 to 0,02 Kg/square meter of net Discussion and conclusion This study represents one of the first attempt in the Mediterranean basin to study depredation by bottlenose dolphins to local fisheries. Despite widespread complaints in the region, an increase of attention to the problem and persistent requests for subsidy, little if any detailed information is available on this topic. A wide range of fishing gears is deployed in different regions and seasons and it is possible that different species of cetaceans may be involved in different kinds of competitive interactions (Lauriano et al., 2004). Since the economy of Lampedusa, biggest island of the Pelagie Archipelago, is mainly based on fishery and tourism, and the Pelagie Archipelago is part of a Marine Protected Area, it is of primary importance to deeply analyse the conflict among fishermen and bottlenose dolphins in that area. This study highlights the existence of what was called ‘operational competitive interaction’ (Northridge and Hofman, 1999; Reeves et al., 2001) between bottlenose dolphins and fishermen. Nevertheless, differences were revealed in the importance of interaction among fishing activity for M. maena and fishing activity for other target species. The analysis of catch’s mean shows a reduction for both type of fishing activity in case of dolphins’ presence. Nevertheless the difference of mean data among surveys with and without dolphins is statistically significant (p<0,05) just for fishing for M. maena, while is not significant for fishing for other species. The dolphin-fishery interaction study would continue for the rest of 2006, in order to confirm those preliminary results. New results would be integrated in further analysis and implemented in the Action Plan for Bottlenose Dolphin in the Pelagie Archipelago, due by 2007 as part of the Life Project. References G. Bearzi, 2002: Interactions between cetacean and fisheries in the Mediterranean Sea. In: G. Notarbartolo di Sciara (Eds.), Cetaceans of the Mediterranean and Black Seas: state of knowledge and conservation strategies. A report to the ACCOBAMS Secretariat, Monaco, February 2002. Section 9, 20 p. J. M. Brotons, 2002: Local conflict with bottlenose dolphins (Tursiops truncatus) repercussions on artisanal fisheries of the Balearic Islands. In: Ecs Meeting, Liege 2002-Proceedings M.M. Fernàndez-Contreras, J.M. Brotons, C. Beltran and A. Aguilar, 2002: Interactions between cetacean and fishing activities in the balearic islands. In: Ecs Meeting, Liege 2002-Proceedings G. Lauriano, C.M. Fortuna, G. Moltedo and G. Notarbartolo Di Sciara, 2004: Interactions between common bottlenose dolphins (Tursiops truncatus) and the artisanal fishery in Asinara Island National Park (Sardinia): assessment of catch damage and economic loss. In: J. Cetacean Res. Manage. 6(2): p. 165–173, 2004 G. Lauriano, S. Di Muccio, A. Cardinali and G. Notarbartolo Di Sciara, 2001: Interactions between bottlenose dolphins and small scale fisheries in Asinara Island National Park (Nort-Western Sardinia). Icram Rapport 2001. Northridge, S.P. and Hofman, R.J., 1999. Marine mammal interactions with fisheries. pp. 99-119. In: J.R. Twiss Jr. and R.R. Reeves (Eds.). Conservation and Management of Marine Mammals. Smithsonian Institution Press, Washington and London. 576pp. A. Zannetti, S. Di Marco, 2002: Interactions between a resident population of bottlenose dolphins (Tursiops truncatus) and fishing activity around the Island of Lampedusa, Archipelago of the Pelagian Islands (Sicily-Italy). In: Ecs Meeting, Liege 2002-Proceedings Acknowledgements We thank all the fishermen of Lampedusa that cooperated with Delta Project. Without them all the information we collected would haven’t had a confirmation in the reality. We thank the Management Board of the Pelagie MPA for its cooperation. We thank all the people that participated to data collection. Fig.4 - 5 The separated analysis among data of gill nets for M. maena, and gill nets for M. surmuletus, without and with dolphins, shows respectively a reduction from 0,22 to 0,02 Kg/square meter of net, and from 0,007 to 0,003 Kg/square meter of net