Addition of Vertical Enrichment Structures Does Not Improve Growth of Three Salmonid Species during Hatchery Rearing

Abstract

Environmental enrichment is the placement of structure or other modifications in typically sterile hatchery rearing units.This study investigated the use of vertically-suspended aluminum rod arrays in covered circular tanks on the rearing performance of brown trout (Salmo trutta), Chinook salmon (Oncorhynchus tshawytscha), and Atlantic salmon (Salmo salar) in separate trials lasting 59, 78, and 125 days respectively. No significant differences were observed in gain, feed conversion ratio, individual fish total length, or individual fish weight between the enriched and unenriched treatments in any of the three trials.In addition, vertically-suspended structure had no significant effect on Atlantic salmon relative fin length. These experiments are the first to indicate no benefits during the rearing of salmonids using vertically-suspended enrichment.