Abstract
The Dutch fishery for flatfish species has changed dramatically over the last 10 years: as a result of high fuel prices, traditional beam trawl using tickler chains to target sole have been replaced by pulse trawls. These pulse trawl use electric stimuli rather than tickler chains to catch bottom dwelling flatfish. Currently, almost all beam trawl vessels targeting sole have switched to pulse trawls. Some vessels occasionally switch back to traditional beam trawling to target plaice. The research and management system storing catch and effort information have not been able to record the transitioning period, i.e. shift from traditional beam trawls to pulse trawls, as it does not distinguish between the two gears. Meanwhile, gear trials suggest different efficiencies for the main target species of the fleet for the two gears. This study uses the existing catch and effort data to estimate changes in efficiency in the beam trawl fleet for a number of commercial species. This requires a two-step approach. 1- The use of either pulse trawl or traditional beam trawl is distinguished using VMS speed profiles, allowing for post-hoc segregation of the data for the two gears. 2- a spatial and temporal model is used to estimate differences in efficiency between the two gears for turbot, brill, sole, and plaice. This efficiency is estimated using different measures of fishing effort, including those that are relevant for the economics and ecological impact of the fishery. Results suggests that the changes in efficiency strongly depend on the measures of fishing effort that are used. In addition, the changes in efficiency appear to differ between species. We hypothesize what could potentially explain these differences.
Original language | English |
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Title of host publication | Abstract book - 10th International Symposium Flatfish |
Pages | 96-96 |
Publication status | Published - 2017 |
Event | 10th International Symposium Flatfish - Saint-Malo, France Duration: 11 Nov 2017 → 16 Nov 2017 Conference number: 10th |
Conference/symposium
Conference/symposium | 10th International Symposium Flatfish |
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Country/Territory | France |
City | Saint-Malo |
Period | 11/11/17 → 16/11/17 |