Abstract
Environmental enrichment has been shown to improve juvenile salmonid growth during hatchery rearing. This study examined the effects of vertically-suspended environmental enrichment starting seven days after feed training and continuing for the next 32 days of landlocked fall Chinook salmon (Oncorhynchus tshawytscha) rearing. At the end of this experiment, final tank weights, gain, percent gain, and feed conversion ratio were all significantly improved in the tanks of salmon with environmental enrichment compared to barren tanks, with a nearly 25% improvement in feed conversion ratio. Individual salmon in tanks with environmental enrichment were significantly longer and weighed significantly more than salmon from tanks without enrichment. Specific growth rate was also significantly improved with the use of enrichment. The use of vertically-suspended environmental enrichment to improve growth and rearing efficiency is recommended during the initial rearing of landlocked fall Chinook salmon.
Highlights
Environmental enrichment is the modification of a typically barren hatchery rearing unit to add complexity or imitate natural environments
This study examined the effects of vertically-suspended environmental enrichment starting seven days after feed training and continuing for the 32 days of landlocked fall Chinook salmon (Oncorhynchus tshawytscha) rearing
Specific growth rate was significantly improved with the use of enrichment
Summary
Environmental enrichment is the modification of a typically barren hatchery rearing unit to add complexity or imitate natural environments. Physical structure has been added to fish rearing tanks as a form of environmental enrichment. Materials located at the bottom of the tank to mimic natural habitats have negative consequences for the hydraulic self-cleaning of circular tanks, leading to decreased water quality, increased labor requirements, and increased disease potential [8]-[13]. In order to add enrichment, but still maintain circular tank hydraulic self-cleaning, vertically-suspended environmental enrichment was developed. 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] [20] [21] [22], showed similar results
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