A comparison of the GOV survey trawl with a commercial whitefish trawl

Abstract

Comparative trials were carried out to evaluate the performance of the GOV (Grande Ouverture Verticale) survey trawl in relation to a commercial whitefish trawl. The gears were rigged in a twin trawl configuration and a comparison of catch rates suggest that, overall, the differences in performance between the two gears are not great, and vary depending on species and whether the commercial gear is fished with or without a tickler chain. There was no difference in relative catch rate for cod (Gadus morhua) between the commercial gear without a tickler chain and the GOV. However, the commercial gear caught fewer small haddock (Melanogrammus aeglefinus) and whiting (Merlangius merlangus) and more larger ones; fewer lemon sole (Microstomus kitt) and more plaice (Pleuronectes platessa) of all sizes. The addition of a tickler chain to the commercial gear significantly increased the catch rate of cod (particularly smaller ones), lemon sole and plaice; but had no significant effect on haddock or whiting. Smaller number of other species were also caught and a comparison of catch weights suggests that there is no difference for saithe (Pollachius virens) and hake (Merluccius merluccius), while the commercial net was better for megrim (Lepidorhombus whiffiagonis) and monkfish (Lophius piscatorius).