Norway’s Institute of Marine Research (HI) has begun its annual monitoring programme tracking sea lice levels on wild salmon, sea trout and Arctic char along the Norwegian coast.
The programme is carried out in cooperation with research organisations NORCE and NINA and forms part of the scientific basis for Norway’s aquaculture traffic light system, which regulates production growth according to the impact of sea lice on migrating wild salmon smolts.
Rune Nilsen, head of the national sea lice monitoring programme, said the surveys provide information on how wild salmonids are affected by lice infestations.
The monitoring has started in southern Norway, beginning in Boknafjord in Rogaland, and will continue northwards through fjord systems in western Norway and Trøndelag before concluding in northern Norway in July.
Researchers use trawls, nets and sentinel cages containing farmed smolts to measure sea lice pressure during the spring migration period, when lice larvae levels typically increase with rising sea temperatures.
According to HI, sea lice levels in the ocean are closely linked to lice levels on farmed salmon in the same area. Heavy infestations can cause wounds, infections and impaired fluid balance in wild fish.