Predicted times and areas of interaction risk between harbour seals and coastal gillnet fisheries in Norway

• Main Author: Elnes, Jonas Oliver
• Format: Master Thesis
• Language: English
• Published: 2021
• Subjects: relative interaction risk; Norway; harbour seal (Phoca vitulina); bycatch; Arctic; Senja; Vesterålen; Arctic cod; harbour seal; North Norway; Northeast Arctic cod; Phoca vitulina
• Online Access: http://hdl.handle.net/10852/87822; http://urn.nb.no/URN:NBN:no-90463

Abstract Incidental take of non-target species by fisheries, also referred to as bycatch, is a major concern for management of species in the marine megafauna. In Norway, 555 harbour seal (Phoca vitulina) die as the result of bycatch each year. The majority of these bycatch events occur in gillnet fisheries. To increase our understanding of harbour seal bycatch events along the Norwegian coast, time and areas of potential interaction risk can be identified, referring to incidents when and where harbour seal foraging and fishing effort overlap. To compensate for the lack on dispersal and movement data on harbour seals in Norway, harbour seal distribution were simulated from their primary moult site to an at-sea location. Overlapping abundances of simulated harbour seal and fishing effort were then used to calculate the relative interaction risks between seals and fisheries in defined Statistical Sea Locations (SSLs), in each season. Seasonality in interaction risk was related to the Northeast arctic cod fisheries, with interaction risks relatively high during winter and particularly spring. Two areas in north and one in west Norway were categorised as Consistently High or moderate Interaction Risk (CHMIR). The relative interaction risk was highest in Vesterålen and Senja (CHMIR2) in north Norway. The CHMIR-areas in general, and particularly CHMIR2 in north Norway, are expected to be the areas where the majority of bycatch events occur in Norway. The method predicts spatial and temporal probabilities for interaction between harbour seals and coastal gillnet fisheries. The located times and areas of interaction risk can be used in management practises to increase our understanding of bycatch events along the Norwegian coast, and to possibly implement mitigation efforts in times and areas with largest effect.