摘要
Although an important part of the natural environment of fish, overhead cover is usually absent during hatchery rearing. To evaluate the possible influence of overhead cover on juvenile brown trout Salmo trutta hatchery rearing performance, this study compared three different cover treatments: near-full (98%) cover, partial (65%) cover, and no cover (completely open). After 12 weeks of rearing in 1.8 m-diameter circular tanks, total tank weight gain was significantly greater and feed conversion ratios were significantly less in tanks of brown trout that were either partially or near-totally covered, in comparison to those tanks that were completely open. The viscerosomatic index, hepatosomatic index, and splenosomatic index values were not significantly different among any of the treatments. Fin condition indices were also not significantly different. The use of either partial or full covers is recommended to maximize brown trout rearing efficiencies, with full covers providing the additional benefit of preventing fish from jumping out of the tanks.
Although an important part of the natural environment of fish, overhead cover is usually absent during hatchery rearing. To evaluate the possible influence of overhead cover on juvenile brown trout Salmo trutta hatchery rearing performance, this study compared three different cover treatments: near-full (98%) cover, partial (65%) cover, and no cover (completely open). After 12 weeks of rearing in 1.8 m-diameter circular tanks, total tank weight gain was significantly greater and feed conversion ratios were significantly less in tanks of brown trout that were either partially or near-totally covered, in comparison to those tanks that were completely open. The viscerosomatic index, hepatosomatic index, and splenosomatic index values were not significantly different among any of the treatments. Fin condition indices were also not significantly different. The use of either partial or full covers is recommended to maximize brown trout rearing efficiencies, with full covers providing the additional benefit of preventing fish from jumping out of the tanks.
