Chemical pollution as a factor affecting the sea survival of Atlantic salmon, Salmo salar L.

The catch of Atlantic salmon Salmo salar L., from ocean and coastal fisheries since 1960 is described and the decline starting in 1973 noted. This decline continued despite cessation of some fisheries, and evidence indicates a marine locus for the decline. Oceanic pollution has received little attention, and ozone loss has caused an increase in UV radiation reaching the surface of the North Atlantic. Direct effects of this increase include negative impacts on the food chain. Photo-induced toxicity of polycyclic aromatic hydrocarbons (PAH) is a possible effect, but concentrations of these compounds in oceanic waters are low. Chlorinated organic compounds are widely distributed in the North Atlantic, and their persistence, lipophilicity, bioaccumulation potential and toxicity represent a potential hazard to salmon. The suggested causes of decline are likely to be complementary rather than exclusive.