Summary
Two models of high field strength neodymium magnets (N35-Ni and N35-NdFeB types) were tested to determine their ability to deter sharks incidentally captured in Spanish and Portuguese longline fisheries operating in the Northeast Atlantic Ocean. The main shark species tested was blue shark (Prionace glauca). The larger magnet was 26 mm X 11 mm X 12 mm, 0.885 T and the smaller magnet was 20 mm X 13 mm X 15 mm, 0.464 t. Field test results indicated the magnets do not reduce blue shark catch rates and may instead have an attractive effect. The attractive effect was significantly higher for the larger magnets.