Traps in the Aegean Sea: alternatives for trawling?
In the deep blue waters of the southern Aegean Sea (Greece) fish are traditionally caught using otter trawls, long lines and bottom nets. In the BENTHIS project, we are searching for alternatives to otter trawls, to reduce the impact of fishing on the seafloor habitat and community. BENTHIS fishery scientist Chris Smith, originally from the UK, has been living and working at the Hellenic Centre for Marine Research (HCMR) in Crete for over 25 years. He believes that baited traps could offer a good alternative to the traditional trawling: “From a theoretical perspective, the baited traps look very promising. They are designed to fish highly selectively, and they hardly damage the seafloor in comparison to trawling”.
He and his research team used two types of traps for the trials: one type of Norwegian cod pot that is deployed off-bottom and has a single entrance and a second on-bottom type with a double entrance. These traps have successfully been used in the cod fisheries in northern European waters. In August 2014 he and his team sailed out with the RV Philia. Chris: ”We fished for 24 hour periods over 10 days in two sites adjacent to commercial trawl fisheries, so that we could compare the catches.” The team focussed on a 70 m deep site over sandy mud characterized by red fish (sparids, red mullet) and a 200 m site with a muddy bottom characterized by white fish (hake, anglerfish) and shrimp. Cameras were installed to monitor the traps and fish behaviour inside and around the traps.
The results were a bit disappointing. Trap catches were very low although the video footage showed some degree of activity by smaller fish, mostly pickerel, that were able to swim in and out of the traps. Comparative trawl catches, fished alongside the trap lines, showed a high diversity of local fish and invertebrates, but with a high by-catch of undersized or non-commercial species. “On the basis of these first trials we will move forward with modifications and come up with some different designs”, says Chris. The new traps will be tested in the next set of trials in the coming winter.
