Abstract
Based on a predictive habitat modelling approach, we investigated 1) the effects of damming on the distribution of salmonids and 2) whether the existing conservation areas for the salmonids are appropriate and effective in protecting their habitats in Hokkaido. A habitat model for masu salmon, one of the most commercially important species, predicted that their occurrence probability declined sharply approximately 30 years after damming. Areas where the probability had significantly dropped due to damming were distributed throughout Hokkaido. A habitat model for the Sakhalin taimen, a salmonid categorized as an endangered species, on the other hand, did not indicate a significant effect of damming on their occurrence, mainly because the taimen inhabit areas with low elevations where dams have not been commonly built. Thirty-two stream systems designated as conservation areas for salmonids by the government of Hokkaido had significantly higher levels of both occurrence probability and conservation value for masu salmon than the other stream systems in the island, but that was not the case for the Sakhalin taimen, indicating an inappropriate placing of conservation areas for this species.
