Effect of Bait Type and Bait Size on Catch Efficiency in the European Hake Merluccius merluccius Longline Fishery

We investigated the effect of bait type and bait size on the catch efficiency of a demersal longline fishery targeting European Hake Merluccius merluccius in the North Sea. Automation of the labor-intensive processes onboard fishing vessels requires finding alternatives to the traditional bait used in the fishery (i.e., whole European Pilchard Sardina pilchardus). Of the six alternative baits investigated, four resulted in significant reductions in catch efficiency ranging from 32% to 90%. Only chopped Atlantic Herring Clupea harengus was a reasonable alternative bait, with an estimated non-significant loss of only 2.12% in European Hake catch efficiency. Our results demonstrated that choice of bait type and size can affect the catch efficiency of different sizes of European Hake. Thus, the choice of bait may also affect the size distribution of the catch. The latter highlights the importance of considering fish size when inferring the effect of bait choice on the catch efficiency of longline fisheries.