Use of Exercise and Structure during Rainbow Trout Rearing

摘要

A combination of two forms of environmental enrichment (in-tank structure and exercise) was evaluated during the hatchery rearing of juvenile rainbow trout Oncorhynchus mykiss. The study used four treatments: 1) neither exercise nor structure, 2) exercise without structure, 3) structure without exercise, and 4) both exercise and structure. Velocities in the unexercised tanks were a constant 12.2 cm-s-1. Velocities in the exercised tanks alternated weekly with one week at 12.2 cm-s-1 followed by a week at 30.5 cm-s-1. Structural enrichment consisted of an array of vertically-suspended aluminum angles. The use of either environmental enrichment technique significantly improved final tank weight, gain, percent gain, and specific growth rate. Feed conversion ratio was significantly and positively influenced only by structure, but fish on the exercise routine were overfed. There were no significant interactions between exercise and structure, indicating that each form of environmental enrichment operates independently. The results of this study indicate fish rearing performance can be improved with the addition of either vertically-suspended aluminum angles or an exercise routine, but the combination of the two techniques may not be needed to improve rainbow trout growth.