Effects of different kinds of fin-clipping on over-winter survival and growth of fingerling brown trout, Salmo trutta L., stocked in small streams in Norway

. Nine thousand fingerling (0+) brown trout, Salmo trutta L., (size 50–90 mm) were fin-clipped in six different ways and released in small streams in September 1984 and 1985. A total of 2625 fish were recaptured by electrofishing the year after stocking. Differences in survival between fin-clip groups were found in one out of eight stockings. No growth differences were found among the several groups. Pectoral and anal fins regenerated most, while adipose fins regenerated least. Single fin-clipping is a recommended marking method for fingerling brown trout during short-term studies. Multiple fin-clips may result in lower survival. Regeneration of fins, especially pectoral and anal fins, make the clipping of these fins less adapted to long-term investigations.