BENTHIS results 2014: Impact of fishing gear: how big are the footprints of trawls and dredges? Otter trawls for flatfish, dredges for oysters, beam trawls for shrimp: the variety of mobile bottom fishing gears in Europe is huge. And they all have different dimensions and impacts, which causes headaches to researchers who want to compare their impacts on the sea bed and the benthic ecosystem. BENTHIS researcher Ole Ritzau Eigaard and his team therefore carried out an industry survey. They wanted to obtain a standardized methodology enabling the prediction of physical impact of individual fishing operations from standard logbook information of vessel size, gear type and catch. First the team conducted a number of industry consultations using questionnaires and interviews, during which more than 1000 questionnaires were filled. From this information, they defined 14 distinct towed gear groups in European waters; 8 otter trawl groups, 3 beam trawl groups, 2 demersal seine groups, and 1 dredge group. These roughly correspond to the métier groupings of EU logbooks that fishermen need to fill in. For each gear type, the BENTHIS team collected detailed information on the individual components, such as doors, sweeps, beam shoes and the ground gear. In this way, the footprint per gear and gear component could be determined. Seafloor penetration of the same components was estimated based on a review of the scientific literature. In addition, the relationship between vessel size (kW or total length) and total gear width/size (door spread, beam width, dredge width and seine rope length) was estimated for each gear group. As expected, the bigger the ship, the bigger the gear. As the EU logbooks currently do not hold any information of gear dimensions, this achievement is a large step forwards in meeting the monitoring requirements of descriptor 6 (seafloor integrity) of the Marine Strategy Framework directive. The next step for the team is to combine the outcome of the gear analyses with European, Norwegian and Turkish logbook and VMS data to produce large scale high-precision maps showing estimates of area and severity of fishing impacts. Contact: Ole Ritzau Eigaard [mailto:[email protected]]
Posted on: Mon, 17 Nov 2014 23:08:00 +0000
Trending Topics
Recently Viewed Topics
© 2015