Temporal synchrony and variation in abundance of Atlantic salmon (Salmo salar) in two subarctic Barents Sea rivers: influence of oceanic conditions

摘要

Long-term variation in Atlantic salmon (Salmo salar) stocks was analyzed in two Barents Sea rivers, theTeno and Näätämöjoki, that represent the northernmost distribution area of the species. In contrast to most of the NorthAtlantic area, these rivers are among a group of northern salmon rivers that, despite wide annual variation in catches,demonstrate no consistent trend for declining abundance. Variations in abundance were generally synchronous for thetotal catch and numbers of 1-sea-winter (1SW) and 2SW salmon during period of 1972–2003. Part of the variation observedin catches could be related to ocean climate conditions as the mean seawater temperature in July during theyear of smoltification for the Kola section of the Barents Sea was significantly related to numbers of 1SW, 2SW, and3SW salmon in the large River Teno. In contrast, NAO (North Atlantic Oscillation) indices were not related to salmoncatches. The latest increase (1999–2001) in salmon catches in these rivers reflects both temporarily improved oceanicconditions and past management measures affecting offshore, coastal, and river fisheries.