A study of discard survival in set-net fisheries

A discard ban in the reformed European Common Fisheries Policy include the possibility of exempting species with proven high discard survival from landing obligation. A high number of the commercial Danish fishing fleet is gill-netters that are mostly fishing coastal. European plaice (Pleuronectes platessa) is a key species for the gill-netters in the North Sea, Skagerrak, and Kattegat. Discard survival in P. platessa from beam and otter trawls range from 0–68%, but survival data on plaice fished with set-nets (trammel and gillnets) is absent from the literature. To investigate discard survival of gill-netters a study, financed by European Fisheries Fund and the Ministry of Environment and Food of Denmark, was established as a cooperation between Aalborg University, Copenhagen University and Foreningen for Skånsomt Kystfiskeri. Experiments were conducted in 2017 and 2018 from smaller coastal commercial gill-netters. Methodology was developed to collect, assess and observe discard survival in P. platessa fished with set-nets. Injury assessments and reflex action mortality predictor (RAMP) tests performed on the fishing vessels immediately after capture, and at the end of the observation periods, revealed substantial recovery of minor catch-related trauma during the observation periods. At the end of the experiment, all fish were sacrificed and dissected to assess the level of long-term internal lesions sustained during capture. All plaice observed so far were alive at the end of the predetermined observation periods. In conclusion, our study document a high discard survival that might justify an exemption of set-nets fished P. platessa from the landing obligation imposed by the European Commission.