Semi-pelagic self-adjusting otter boards: effects on the catching performance of a demersal trawl

• Published in: Canadian Journal of Fisheries and Aquatic Sciences
• Main Authors: Eighani, Morteza, Malta, Tiago Veiga, Melli, Valentina, O'Neill, Finbarr G.
• Other Authors: Ministry of Environment, Green Development and Demonstration Program
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 2024
• Subjects: Gadus morhua
• Online Access: http://dx.doi.org/10.1139/cjfas-2023-0224; https://cdnsciencepub.com/doi/full-xml/10.1139/cjfas-2023-0224; https://cdnsciencepub.com/doi/pdf/10.1139/cjfas-2023-0224

In this study, we investigate whether replacing conventional seabed-contacting otter boards with semi-pelagic self-adjusting otter (SAO) boards, which have the ability to maintain a given height above the seabed, affects the catch efficiency of a demersal fish trawl. Experimental fishing trials, using the alternate haul method, were conducted in the Kattegat and Skagerrak with three otter board configurations using conventional seabed-contacting otter boards; the SAO set to maintain a target height over the seabed of 1 m; and the SAO set to maintain a target height of 5 m. Replacing conventional otter boards with SAO resulted in a loss of catch efficiency for haddock ( Melanogrammus aeglefinus), whiting ( Merlangius merlangus), and plaice ( Hippoglossoides platessoides), while no significant difference was found for cod ( Gadus morhua), common dab ( Limanda limanda), and lemon sole ( Microstomus kitt). When comparing the SAO-1 m and SAO-5 m, it was observed that SAO-5 m resulted in a loss of catch efficiency for haddock and plaice, a minimal reduction for cod, and no significant difference for whiting, common dab, and lemon sole.