The effect of invading harp seals ( Phoca groenlandica) on local coastal fish stocks of North Norway

Abstract

Annual invasions of harp seals ( Phoca groenlandica) into coastal areas and fjords of northern Norway during the last decade have created problems for fisheries in the area. Bottom-trawl survey data collected during 1986–1990 in Ullsfjord were used to evaluate possible interactions between invading seals and local fish stocks. The presence in seal stomachs (sampled in Ullsfjord) of saithe ( Pollachius virens) and small cod ( Gadus morhua), which were not frequent in trawl catches, seems to indicate that seals may pursue prey in waters other than the trawl areas. Many of the species occurring in the seal stomachs were, however, also encountered quite frequently in the trawl catches. Harp seals may cause considerable damage to gill-net catches by eating parts (usually the ventral soft parts) of fish entangled in the nets.