engleski

Incidental captures of sea turtles in the northern Adriatic Sea

All the three sea turtles species occurring in the Mediterranean have been reported from the North Adriatic Sea. Chelonia mydas and Dermochelys coriacea occur occasionally while for the loggerhead sea turtle Caretta caretta, this area represents one of the most important neritic habitats of the Mediterranean. Unfortunately, the high turtle concentration and the high fishing effort in the area by vessels from the three surrounding countries (Italy, Croatia and Slovenia) result in high bycatch and consequent mortality. Up to now there is evidence of incidental capture by at least three fishing gear: bottom trawl, midwater trawl, and set nets (trammel and gill nets). Results of onboard observation programmes indicate that the total number of captures range from a minimum of 7, 100 to over 10, 000 per year. The overall mortality is difficult to assess because mortality rate depends on the haul duration (the higher the duration, the higher the mortality due to forced apnea) which varies depending on areas or even single vessels. Direct mortality (dead at gear retrieval) is estimated at 10-12%, but an additional delayed mortality (death after release) is suspected to be much higher. Preliminary studies suggest that midwater trawl catches less turtles and with a lower mortality than bottom trawl. Specific investigation on set nets is ongoing in Croatia and is providing evidence of a high impact by this artisanal fishing gear: estimates range from 650 to 4000 captures per year with a very high mortality rate, possibly 75%. Although far to be fully assessed, mortality induced by fishing gear in this area clearly represents a heavy toll for Mediterranean turtle populations, at least for the Greek one. For this reason, conservation measures are deemed as necessary and urgent.

sea turtles; fishery; bycatch; Adrtiatic Sea

nije evidentirano