Use of semi-pelagic trawling for reducing bycatch in shrimp trawls. Trials onboard R/V Johan Ruud 02-06 February 2015

Abstract

The present study evaluates whether lifting the trawl doors and sweeps from the seabed can reduce bycatch in shrimp trawl fisheries. We carried out a catch comparison and catch ratio analysis between two gear setups, one with the trawl doors and sweeps at the seabed (the traditional way) and the other with the doors and sweeps lifted. The study was carried out on American plaice. The results showed that when fishing with the doors and sweeps at the seabed, the gear is significantly more efficient at catching flatfish. The gear setup with the doors and sweeps at the seabed captures between 50% and 70% more American plaice than the gear setup with the doors and sweeps lifted. This difference is significant for sizes between 10 and 36 cm. Further, this efficiency is size dependent and increases with fish size. The results obtained are encouraging for the shrimp fishing industry as lifting the doors and sweeps from the seabed could help mitigate fish bycatch problems, and reduce bottom impact. Further studies are recommended to investigate if lifting the doors and sweeps from the seabed is equally efficient at reducing bycatch of other species, and if it also affects the shrimp catches.