Fishing victims, marine turtles; Does the ted grid system work on the traditional trawl nets of the eastern Mediterranean?

<p>Ertan Taskavak</p>

Fishing victims, marine turtles; Does the ted grid system work on the traditional trawl nets of the eastern Mediterranean?

Ertan Taskavak

Ege University, Tukrkey

: J Mar Biol Oceanogr

Abstract

Together with Nile soft-shelled turtle, Trionyx triunguis, an actually fresh water turtle, two species of sea turtles, Chelonia mydas (Green turtle) and Caretta caretta (Loggerhead turtle) occur and have nesting beaches at the Mediterranean coasts of Turkey. All conservation measures taken into consideration for these species mainly based on the nesting habitats, eggs and hatchlings. In spite of various data on sea turtle mortalities such as where turtle captures occur, which species are more impacted, at what depths the majority of captures occur, and how many turtles are captured and killed by shrimp trawls, there is not any conservative measure for these species captured incidentally by commercial shrimp trawlers. In this study, the Turtle Excluder Devices (TEDs), which have been developed principally to allow discarding of sea turtles, were practiced to adapt into the shrimp trawls used in Eastern Mediterranean. One of the hard TEDs, Super Shooter, was determined to be most suitable for the traditional prawn trawls. The effects of extension and flaps on the fish harvest were not taken into consideration in experimental trawling. It is observed that both Caretta caretta and Chelonia mydas was excluded by the modified super shooter. In addition to the suitable model tested, we also observed and recorded the behaviors of both marine turtles in trawl body. In eastern Mediterranean of Turkey, the most dominated species caught by prawn trawls is Trionyx triunguis. Besides, it was recorded that the amount of fish in the trawl with TED was higher than those without TED. Using underwater cameras, the situations of the trawl net, grids and two sea turtles were monitored. Consequently, the TED system we modified can operate even more efficiently in a prawn trawl net where the grid angle is reduced and the flap length is somewhat longer.