The study was aimed at comparing mortality and growth rate of the brown trout fry released, in autumn 2001 and spring 2002, to three tributaries of River Kamienica Nawojowska (the River Dunajec system in southern Poland). The released fish were tagged by adipose fin clipping and Alcian Blue injection. The recapture operations were conducted on 1 March and 2 September 2002. The fry released in autumn showed a higher daily instantaneous mortality rate than that found in the brown trout released in spring. The daily instantaneous growth rate was distinctly lower in the fish released in autumn than in those stocked in spring. The daily instantaneous mortality and growth rates were significantly dependent on the fry size.

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