Structural complexity in the hatchery rearing environment affects activity, resting metabolic rate and post-release behaviour in brown trout Salmo trutta.

The effects of structural enrichment in the hatchery rearing environment of brown trout Salmo trutta was linked to post-release performance. Enrichment resulted in reduced swimming activity scored in an open field test and reduced movement in a natural river after release. Also, enrichment increased resting metabolic rates, which correlated positively with overwinter growth.