Turtle Excluder Devices for Multispecies Bottom Trawls in the Mediterranean: Current Performance and the Need for Further Adjustments

Bycatch from bottom trawling is a major threat to Mediterranean loggerhead turtles. Building on previous trials of Turtle Excluder Devices (TEDs), this study aimed to expand sample size and geographic coverage to assess TED effectiveness in Mediterranean multispecies bottom trawlers. Flexgrid TEDs were tested on nine bottom trawlers operating in the Gulf of Manfredonia and south of the Po River in the Adriatic Sea—areas heavily used by both bottom trawlers and loggerhead turtles. Onboard observers recorded target, discard and turtle catch from different gear configurations, such as an external sac applied to the TED opening (TEDe) as well as nets with and without TEDs. Of the 18 turtles captured, two were decomposed upon capture. Among the 16 potentially captured alive, none were found in the codends of TED-equipped nets. However, some vessels experienced important reductions in commercial catch when using TEDs. Catch loss induced by TED vs. regular gear was estimated as −16.6% by a GLMM, while a mean loss of 19.7% was directly observed in TEDe. Results show high variability among hauls, likely influenced by environmental factors and vessel characteristics, and are consistent with previous studies in the Adriatic Sea. TED design should be further improved, especially with direct involvement of fishers, and should be tested across different fisheries and regions.