Evaluation of protein hydrolysate of by-product from the fish industry for inclusion in bait for longline and pot fisheries of Atlantic cod

In this study, we investigated the behaviour of Atlantic cod (Gadus morhua) toward three commercially available protein hydrolysates made from shrimp (Pandalus borealis), blue mussels (Mytilus edulis) and capelin (Mallotus villosus), and used blank (seawater) as control. The shrimp and blue mussel attractants were based on industrial waste products, whereas the capelin attractant was produced from industrial quality of capelin. The attraction behaviour study took place during two experimental periods in a 6-m diameter, 28-m3 volume circular tank set up for behavioural studies: Experiment 1 during April 2013, and Experiment 2 during May 2013. In Experiment 1, there were highly significant differences in frequencies of inspections between attractants and controls for shrimps and blue mussel attractants, whereas the inspection of capelin attractants did not occur more frequently than the control. The comparison between the different attractants in experiment 2 enabled a ranking between them, which showed significant higher frequency of interaction with shrimp hydrolysate. The capelin produced lowest frequency of interactions, similar to the first trial, but there were no significant difference between blue mussels and capelin. Results from this study show that hydrolysate from shrimps and blue mussel have the potential to replace natural bait for cod.