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

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.

Use of Exercise and Structure during Rainbow Trout Rearing

“…This is similar to the results of other studies using high velocities for exercise or not allowing for any rest periods [25] [44] [45], which all likely produced exercise fatigue [42] [34]. It must be noted however, that the results from using structure in this study differ from those of White et al [28], Huysman et al [31], and Jones et al [33]. These differences could be due to differences in the size and species of fish used in each experiment, as well as the duration of each study.…”

Vertically-Suspended Environmental Enrichment Improves Growth of Landlocked Fall Chinook Salmon during Initial Hatchery Rearing

“…Kientz and Barnes [14] and Kientz et al [15] reported an increase in rainbow trout (Oncorhynchus mykiss) growth using suspended aluminum rods and suspended strings of plastic spheres. Subsequent studies used a variety of vertically-suspended structures with a variety of salmonid species, including Chinook salmon (Oncorhynchus tshawytscha) [16]; brown trout (Salmo trutta) [17], Atlantic salmon (Salmo salar) [18], and rainbow trout [19] Although there have been numerous studies examining vertically-suspended environmental enrichment during the hatchery rearing of salmonids in circular tanks, these studies have primarily used juvenile or larger fish. No studies have examined the use of such enrichment beginning with initial feeding.…”

Color of Vertically-Suspended Structure Does Not Impact the Growth of Rainbow Trout Reared in Circular Tanks

“…In conclusion, the results of this study indicate that the color of vertically-suspended environmental enrichment structures likely has little impact on rainbow trout growth in covered circular tanks. Thus, the inherent silver (unpainted aluminum) color of such structures does not need to be changed to produce additional rainbow trout rearing benefits beyond those of just using the structures themselves [19] [38]. Additional research investigating the effects of environmental enrichment colors should be conducted with other fish species and sizes.…”