The REFISH (restoring endangered fish in stressed habitats) project, 1988?1994

Abstract

The REFISH (Restoring Endangered Fish In Stressed Habitats) Project was established in 1988 to assess acid-tolerance among indigenous Norwegian strains of brown trout. The work, comprising both laboratory and field studies, has involved the restocking and subsequent test-fishing of thirteen lakes with five brown trout strains. There was considerable variation in the ability of individual lakes to support adult trout. This did not appear related to ANC (acid neutralising capacity) or any single chemical factor. One strain, Bygland, was found to be relatively acid-tolerant, accounting for more than 60% of all fish recaptured by test-fishing over 1990–1994. This is consistent with better survival of young life-stages of the Bygland strain, compared with that of the other strains, in laboratory experiments employing acidic conditions. Strainspecific differences in calcium metabolism may be the physiological basis for acid tolerance.