Lost and abandoned nets in deep-water gillnet fisheries in the Northeast Atlantic: retrieval exercises and outcomes

The methods used and the results, including estimates of ghost catches present at the time of retrieval, from Irish and UK (England and Wales) gillnet retrieval exercises carried out in deep-water gillnet fisheries west of the British Isles are described. Summaries of the exercises are currently found only in the grey literature, and there is a need to make them more widely available to the scientific community. The fisheries are currently principally for anglerfish (mainly Lophius piscatorius), along with a small bycatch of deep-water sharks [mainly leafscale gulper shark (Centrophorous squamosus) and Portuguese dogfish (Centroscymnus coelolepis)]. The methods used and the results from retrieval exercises in the Norwegian Greenland halibut (Reinhardtius hippoglossus) gillnet fishery are also presented. It is suggested that the efficiency of the Norwegian retrieval gear (which was used in all but one of the retrieval exercises described) be investigated under a range of conditions using an attached underwater camera. The outcomes from this could be used to improve the design of retrieval gear and future gillnet retrieval survey/mitigation exercises. Suggestions are made to improve the format and interpretation of results from future retrieval surveys and to enhance their value to fishery managers and stock assessment scientists. The importance of the continued need for structured gillnet retrieval exercises in deep-water gillnet fisheries is emphasized, and suggestions are made for conducting future studies.