Design and Test of a Topless Shrimp Trawl to Reduce Pelagic Fish Bycatch in the Gulf of Maine Pink Shrimp Fishery

Abstract

A new innovative topless shrimp trawl was designed and tested in the flume tank, and at sea to evaluate its potential of reducing finfish bycatch in the pink shrimp fishery in the Gulf of Maine. The trawl design removed the square and the top part of the section after the square (first belly section), to become “topless”. A five-day sea trial was carried out using the alternating tow method to compare the topless trawl and a commercial (control) trawl. The target species was the pink shrimp (Pandalus borealis) and the major bycatch species was Atlantic herring (Clupea harengus) that formed 90.6% of all bycatch by weight. Comparative fishing indicated that the topless trawl reduced bycatch of Atlantic herring by an average of 86.6%, and at the same time produced a modest increase of 13.5% in the catch of the pink shrimp. There was some increase in the bycatch of flounders, particularly American plaice and winter flounder, though overall amount of flounder bycatch was less than 3% of the total catch. The reduction of Atlantic herring was most likely due to the fish escaping over the headline where the top panel was removed. The increased bycatch of flounders (and increased catch of shrimp) might have resulted from a wider wingend spread and subtle differences in the footgear between the topless and commercial trawls. The substantial reduction of Atlantic herring, the major bycatch species, without a reduction of the target shrimp species proved the concept of the topless trawl and may have a profound impact on other shrimp trawl fisheries around the world.