Field study to assess some mitigation measures to reduce bycatch of marine turtles in surface longline fisheries

This project worked with fishermen to test hook and bait types in European surface longline fisheries in the Atlantic, eastern and western Mediterranean with the aim of assessing whether they reduce turtle by-catch. Gear modifications to reduce turtle bycatch may also have an effect on the ability of the gear to catch the target species, swordfish. This is a prime concern of fishermen, thus the effect of gear modifications on target species catch rates were also assessed, allowing potential measures to be identified which not only reduce turtle bycatch but also minimise any detrimental effect on swordfish catches.

An initial review of previous studies on mitigation measures for reducing turtle bycatch allowed a robust design to be developed for a series of three at-sea experiments on board commercial fishing vessels. These took place in swordfish fisheries in three sea areas, the southeast Atlantic, the eastern Mediterranean and the western Mediterranean and rigorously tested three types of hooks and two types of bait. A survey of fishermen was also undertaken in the three areas to investigate the current gears in use, fishermen's perception of the turtle bycatch problem and their attitude to changes in gear.