Effects of Turtle Excluder Devices on bycatch and discard reduction in the demersal fisheries of Mediterranean Sea

¹ Consiglio Nazionale delle Ricerche (CNR), Istituto di Scienze Marine (ISMAR), Sede di Ancona, National Research Council (CNR), Institute of Marine Sciences (ISMAR)Section of Ancona, Largo Fiera della Pesca, 60125 Ancona, Italy
² Fondazione Cetacea ONLUS, Viale Torino 7/A, 47838 Riccione ( RN), Italy

^a Corresponding author: a.sala@ismar.cnr.it

Received: 14 October 2010
Accepted: 15 March 2011

Abstract

The Central Mediterranean provides important neritic habitats for loggerhead turtles (Caretta caretta), but Mediterranean bottom trawlers catch an estimated 30 000 turtles a year, with 25% mortality. Mortality by trawling is mainly due to enforced apnoea during towing activity. In order to reduce the submergence time and consequent turtle mortality, a specific technical modification was developed in the early 1980s: the Turtle Excluder Device (TED). In this paper, we field-tested a typical Supershooter TED and three new types of low-cost TED, built with different designs and materials, incorporating aspects of US and Australian TEDs, as well as design features to improve handling and catch rates. The performance of the TEDs was investigated under commercial fishing conditions in diverse trawling grounds in the Adriatic Sea (Mediterranean). All TEDs were easy to operate and did not require changes to normal fishing operations. Due to lack of entry of turtles it was not possible to evaluate the ability of the different TEDs to release turtles, but one large loggerhead turtle (C. caretta) was captured during the experimental tows and was successfully excluded by the Supershooter. The TEDs reduced anthropogenic debris and, consequently, sorting operations on board. Among the four TEDs tested, both the semi-rigid TED and the Supershooter performed in accordance with the design objectives: total discards were reduced but total commercial catches were not significantly reduced. With the Supershooter, all European hake (Merluccius merluccius) individuals equal to or above 16 cm were found in the codend and 10–15% of those between 5.0 and 15.5 cm were released. In general, the total discard rate of the TED-equipped nets was reduced to around 20–60%. Since the Council Regulation (EC) No. 1967/2006 called for a discard reduction policy in waters under the jurisdiction of the European Union, TEDs may have some broader value in this context.