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 cost-effective approach capable of providing sufficient data to estimate annual bycatch rates and identify high-risk gear/location/season combinations.
Highlights
Mediterranean fisheries are essentially multi-species and multi-gear
Data are presented by Geographical Sub-Areas (GSAs) of the General Fisheries Commission for the Mediterranean comprising the Italian coastline, assuming that the bycatch relating to each fishing method and environmental condition in each GSA are sufficiently similar to provide a homogenous bycatch amount
The fishing effort was the highest in GSA 17 (Northern Adriatic Sea), where the low depth, flat seabed is ideal for towed gears, but fell in summer due to the closed fishing season
Summary
Mediterranean fisheries are essentially multi-species and multi-gear. Fishing fleets consist mostly of medium to large, highly differentiated, competing vessels that often exploit shared resources (Lucchetti et al, 2014). Large vertebrates like sharks (Ferretti et al, 2008), cetaceans (Bearzi, 2002), monk seals (Karamanlidis et al, 2008) and, above all, sea turtles (Casale, 2011) are the most affected species These species are vulnerable for biological reasons including late maturity and low reproduction rates. The loggerhead sea turtle (Caretta caretta, Linnaeus, 1758) is the most abundant sea turtle species in the Mediterranean Sea (Casale & Margaritoulis, 2010 and references therein; Lucchetti & Sala, 2010) It is a priority species in Appendix II/IV of the Habitats Directive, the cornerstone of the EU nature conservation policy, which lists animals requiring close protection (EU, 1992). C. caretta is included in the red list of the International Union for the Conservation of Nature and Natural Resources
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