Increasing efficiency in pelagic/semi-pelagic trawling

摘要

It is common knowledge that a lot of the catch seen in the trawl opening on the Trawl Eye or trawl sonar does not end up in the codend. While there are many critical factors for catch efficiency, the fact that scientific studies reveal efficiency to be as low as 20% in some cases is food for thought. There is also a second major problem with fish escaping, which is that many of them subsequently die from injury.This occurs notably in areas of small mesh size, but not in the area with the smallest mesh. Some idea of this can be obtained by looking at how the trawl is 'cloaked'; but this does not give the full picture in areas of large mesh size, where many fish can escape but stickers are rarely found.