Use of Suspended Plastic Conduit Arrays during Brown Trout and Rainbow Trout Rearing in Circular Tanks

Abstract

AbstractEnvironmental enrichment is the modification of otherwise sterile hatchery rearing units to provide structural complexity. We investigated the use of an array of suspended plastic conduit sections as enrichment in large circular tanks during two experiments. Brown Trout Salmo trutta and Rainbow Trout Oncorhynchus mykiss were reared for 126 and 61 d, respectively, in covered, 3.63‐m‐diameter circular tanks that were either void of any structure or enriched with a suspended array of twenty 0.94‐m‐long sections of plastic conduit. Total tank weight gain and feed conversion ratio were significantly improved for both Brown Trout and Rainbow Trout reared with suspended conduit as enrichment compared to unenriched tanks. Enrichment did not significantly affect individual fish length, weight, or condition factor in either experiment, likely because of small sample sizes. The suspended array did not interfere with tank hydraulic self‐cleaning. Based on the results of this study, the use of vertically suspended enrichment structures in circular tanks is recommended to improve trout rearing efficiencies.