Selectivity of 130 mm Mesh Size in Deep Sea Bottom Trawl Fishery in NAFO Regulatory Area

Abstract

In February 1995 the European Union carried out a selectivity survey on board a Spanish commercial trawler, using the codend-cover method. The objective was to study the selectivity of 130 mm mesh size for the deep sea trawl fisheries in the NAFO Regulatory Area. One hour and four hour hauls were carried out and results obtained for Greenland halibut (Reinhardtius hippoglossoides), American plaice (Hippoglossoides platessoides), roughhead grenadier (Macrourus berglax) and threebeard rockling (Gaidropsarus ensis). For the two flatfish species, the proportion of retention increased with the duration of the haul. This increase reflected in a decrease of the corresponding selection factor. It also varied with the size of fish. The selection factor was greater in smaller individuals, and this induced an asymmetry in the selectivity curve. For the groundfish species, data were enough only to fit the four hour selectivity curves, which appeared more symmetrical than the flatfish ones.