Rearing Performance of Atlantic Salmon Grown in Circular Tanks with Vertically-Suspended Environmental Enrichment

Misty D Jones,Eric Krebs,Jill M Voorhees,Michael E Barnes,Nathan Huysman

doi:10.4236/ojas.2019.92021

Abstract

Environmental enrichment is the incorporation of materials into hatchery tanks to simulate a more natural rearing environment. This study investigated the use of a vertically-suspended plastic conduit array as enrichment in 3.63 m circular tanks during Atlantic salmon (Salmo salar) rearing. After 168 days, feed conversion ratio was significantly improved for salmon reared in tanks with enrichment compared to the barren control tanks. Final tank weights and weight gain were not significantly different, although the difference in mean gain of 182.0 kg in the enriched tanks compared to 162.9 kg in the control tanks approached significance. There were no significant differences in individual fish length, weight, or condition factor between the treatments, likely because of large variances in body size due to sexual dimorphism and small sample sizes. The suspended array did not interfere with the hydraulic self-cleaning of the circular tanks. The results of this study support the use of vertically-suspended structures to improve the hatchery rearing performance of Atlantic salmon in circular tanks.

Highlights

Environmental enrichment is the addition of material within a barren hatchery rearing unit to imitate natural environments normally encountered by fish
This study investigated the use of a vertically-suspended plastic conduit array as enrichment in 3.63 m circular tanks during Atlantic salmon (Salmo salar) rearing
Feed conversion ratio was significantly improved in the tanks of Atlantic salmon containing environmental enrichment compared to control tanks (Table 1; F1,4 = 4.867, P = 0.092)

Summary

Introduction

Environmental enrichment is the addition of material within a barren hatchery rearing unit to imitate natural environments normally encountered by fish. It has been used in an attempt to alter fish behavior and physiology to improve hatchery rearing performance or post-stocking survival [1]-[9]. While these supplements attempt to replicate a natural environment, they disrupt the hydraulic self-cleaning of circular tanks. There may be a potential increase of disease outbreaks and increased labor requirements from hatchery staff [14] [15] [16] [17]

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Conclusion