Exercise and Structure Improve Juvenile Chinook Salmon Rearing Performance

Abstract

This experiment evaluated the use of an exercise routine and vertically-sus - pended structure during juvenile landlocked fall Chinook salmon ( Oncor hynchus tshawytscha ; mean ± SE, initial weight 1.47 ± 0.03 g, total length 56.4 ± 0.4 mm) rearing. Four treatments were used: 1 ) no exercise routine nor vertically-suspended structure, 2 ) exercise and structure, 3 ) exercise and no structure, and 4 ) no exercise and structure. Water velocities in tanks without exercise were 12 cm/s, where-as the exercise routine consisted of seven days at 12 cm/s followed by seven days at 18 cm/s. The structure was an array consisting of four vertically-suspended aluminum angles. Total tank gain and percent gain were significantly greater after 50 days in the tanks of salmon subjected to the exercise routine and structure compared to the three other treatments. Gain and percent gain were also significantly greater in the tanks receiving structure without exercise compared to tanks with exercise and no structure or tanks with neither exercise nor structure. Feed conversion ratio was signif icantly improved in the salmon tanks with structure and without exercise com pared to all other treatments. There were no significant differences for indi vidual fish weight, total length, specific growth rate, or condition factor among any of the treatments at the end of the experiment. These results indicate that the use of both an exercise routine and vertically-suspended structure may be beneficial during the rearing of juvenile landlocked fall Chinook salmon.