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VALUTAZIONE DELLE CATTURE ACCIDENTALI DI SPECIE PROTETTE NEL TRAINO PELAGICO -Estensione 2011 RELAZIONE FINALE DEL PROGETTO
Bycatch is one of the main sources of anthropogenic mortality of species of conservation concern worldwide. Between January 2011 and May 2012, ISPRA coordinated a monitoring programme of cetacean bycatch in Italian pelagic trawlers (BYCATCH III extension 2011), funded in compliance with the Regulation (EC) No.812/2004. Other 3 partners participated in the monitoring, data collection and analyses: CoNISMa, CNR ISMAR of Ancona and the University of Florence. Thirteen independent observers monitored a total of 2,735 hauls. The average observation coverage was 2.4% during the duration of the entire project, ranging between 3.4-4.4 % of the regional fishing effort in 2011. Almost all bycatch events were recorded in the northern Adriatic Sea. Bycatch rates of bottlenose dolphins (Tursiops truncatus) and loggerhead turtles (Caretta caretta) were 0,001 (3 events) and 0,010 (18 events) specimen/haul, respectively. The 2011 estimated annual number of bycaught bottlenose dolphins in this fishery for the GSA 17 was 72 specimens (CV=0.55; 95% CIs=39-104). Despite the high degree of uncertainty, this estimate rise some concern about the sustainability of this accidental captures at the Adriatic level. It is urgent to determine whether or not the scale of this mortality, in addition to that caused by all other fishing gears, is sufficient to pose a threat at the population level. The 2011 estimated annual number of bycaught sea turtles in this fishery for the GSA 17 was 358 specimens (CV=0.29; 95% CIs=296-402), 99% of which released alive. The extent of lethal interactions for common thresher shark (Alopias vulpinus), eagle ray (Myliobatis aquila) and bull rays (Pteromylaesus bovinus) should also be evaluated. Bycatch of elasmobranchs commercial species (e.g. Squalus acanthias and Mustelus spp) should also be carefully considered.