An interview-based approach to assess sea turtle bycatch in Italian waters

Abstract

The loggerhead sea turtle (Caretta caretta, Linnaeus, 1758) is the most abundant sea turtle species in the Mediterranean Sea, where commercial fishing appears to be the main driver of mortality. So far, information on sea turtle bycatch in Italy is limited both in space and time due to logistical problems in data collected through onboard observations and on a limited number of vessels involved. In the present study, sea turtle bycatch in Italian waters was examined by collecting fishermen's information on turtle bycatch through an interview-based approach. Their replies enabled the identification of bycatch hotspots in relation to area, season and to the main gear types. The most harmful fishing gears resulted to be trawl nets, showing the highest probabilities of turtle bycatch with a hotspot in the Adriatic Sea, followed by longlines in the Ionian Sea and in the Sicily Channel.Estimates obtained by the present results showed that more than 52,000 capture events and 10,000 deaths occurred in Italian waters in 2014, highlighting a more alarming scenario than earlier studies. The work shows that in case of poor data from other sources, direct questioning of fishermen and stakeholders could represent a useful and costeffective approach capable of providing sufficient data to estimate annual bycatch rates and identify high-risk gear/location/season combinations. The loggerhead sea turtle (Caretta caretta, Linnaeus, 1758) is the most abundant sea turtle 10 species in the Mediterranean Sea, where commercial fishing appears to be the main driver of 11 mortality. So far, information on sea turtle bycatch in Italy is limited both in space and time due 12 to logistical problems in data collected through onboard observations and on a limited number of 13 vessels involved. In the present study, sea turtle bycatch in Italian waters was examined by 14 collecting fishermen's information on turtle bycatch through an interview-based approach. Their 15 replies enabled the identification of bycatch hotspots in relation to area, season and to the main 16 gear types. The most harmful fishing gears resulted to be trawl nets, showing the highest 17 probabilities of turtle bycatch with a hotspot in the Adriatic Sea, followed by longlines in the 18 Ionian Sea and in the Sicily Channel. Estimates obtained by the present results showed that more 19 than 52,000 capture events and 10,000 deaths occurred in Italian waters in 2014, highlighting a 20 more alarming scenario than earlier studies. 21 The work shows that in case of poor data from other sources, direct questioning of fishermen and 22 stakeholders could represent a useful and cost-effective approach capable of providing sufficient 23 data to estimate annual bycatch rates and identify high-risk gear/location/season combinations. 26 mostly of medium to large, highly differentiated, competing vessels that often exploit shared 27 resources (Lucchetti et al., 2014). Intense and prolonged fishing pressure has resulted in 28 overexploitation of fish resources (Colloca et al., 2013) a...