Cessation of the Norwegian drift net fishery: changes observed in Norwegian and Russian populations of Atlantic salmon

The aim of this study was to evaluate effects of the ban on the Norwegian c oastal drift net fishery in 1989 on the spawning run of Atlantic salmon (Sa lmo salar) populations in four Norwegian and four Russian rivers. Catches/e scapements, size distribution, sea-age proportions, and mean weights of dif ferent sea-age groups were collected from official catch statistics and ana lyses of scale samples. In three of the Norwegian rivers, catches of grilse (1SW) increased significantly after the ban on the drift net fishery. No c hanges were recorded for multi-sea-winter (MSW) fish. In addition, the prop ortion of grilse increased in all the Norwegian rivers, and 2SW salmon incr eased in three of them. The mean weight of grilse increased in all four Nor wegian rivers, whereas the mean weight of 2SW fish decreased in the two riv ers in southern Norway. The size of 3SW fish did not change. These changes correspond well to actual net selection curves and reported mean weight of drift net catches in different parts of Norway. Trends in the Russian popul ations were more varying. In the three rivers draining to the Barents Sea, changes were similar to those in the Norwegian rivers. However, these chang es were less obvious than those observed in Norwegian populations. The auth ors conclude that the ban of the drift net fishery significantly affected t he structure of the spawning run in Norwegian Atlantic salmon populations. Furthermore, the results indicate that the drift net fishery affected Russi an salmon populations in rivers draining to the Barents Sea to a lesser ext ent than Norwegian salmon, and had no effect in rivers draining to the Whit e Sea. (C) 1999 International Council for the Exploration of the Sea.