Selection and mortality in pelagic longline fisheries for haddock

Abstract

The bycatch of haddock (Melanogrammus aeglefinus) below legal size in the pelagic longline fisheries for haddock off the coast of Finnmark, northern Norway, is often high. This project was aimed at reducing the bycatch of undersized haddock through alterations in gear technology and fishing strategy. Fishing experiments with commercial longline vessels were carried out in JuneIJuly 1995 and 1996. The following modifications of fishing gear and fishing technology were tested: longlines with increased sinking speed; hooks with an inedible plastic body attached to the shank; hooks with nylon bristles attached to the shank; restructured bait based on mackerel (Scomber scombrus) and sandeel (Ammodytes lancea); mackerel bait of twice the normal size; restructured mackerel bait of twice the normal size. None of the methods tested gave the desired improvements in the size distribution of the haddock catches. Traditional mackerel bait of twice the normal size about 40% reduction in undersized fish, but an increase in bait costs due to larger bait size, will not be accepted by commercial fishermen. In the survival experiments, where 18 haddock were torn off the longline hooks at the sea surface and kept in sea water tanks for five days, no mortality was found. One of the fishes was in bad condition at day five, and would probably not have survived if it was released to the sea. Additional experiments have to be carried out to confirm these results.