In the Mediterranean, the number of sea turtles captured by the fleet of bonito fishermen is considerable in relation to those caught by the tuna and swordfish fleets, due to the smaller size of the hooks. This fact puts into doubt the effectiveness of the circular hook when it is used in smaller sizes than those used to fish bonito and damselfish. Also, the injuries that can be caused by deep anchoring are unknown. 

On the other hand, the fishing lines attached to these hooks are as dangerous, if not more, than their own hooks. On many occasions, fishermen hoist sea turtles on board hanging from the fishing line. This causes serious injuries to the gastrointestinal system of these animals. In addition, when releasing the turtles, the fishermen tend to cut the fishing line at a length too long (greater than the length of the turtle). In this case, the probability of the captured turtle surviving is practically nil, since the fishing line is already ingested and can provoke a syndrome known as ¨the accordion effect¨, which results in a 100% mortality rate.

With this data in mind, during the scientific campaign of the Vell Marí in 2006, a study was developed with collaboration from the long-line fisherman in Balearian waters whose objectives were as followed:

• To realise a field study from a long-line fishing boat to analyze the number of incidental captures of the loggerhead turtle (Caretta caretta) and the effectiveness of fishing with circular hooks in comparison to the traditional ¨J¨ hooks.
• To realise a study to find the most frequent anatomical location of hooks caught in turtles based on the type of hook, comparing the seriousness of injury and analyzing the associated mortality rate.
• To show the fisherman the proper techniques to free captured turtles causing the least damage possible to the turtle.

Watch the final report in PDF format:

Report [Size 1,2 Mb]

A turtle captured on a long-line

Rescue Actions:

• Small cetaceans
• Great cetaceans
• Elasmobranches
• Turtles-Actions with fishermen

The long-line fishing boat and Vell Marí

During the campaign, the collaborating fishermen were trained in the use of tools that diminish the mortality rate of captured turtles

Poster