The Effect of Environmental Enrichment on Agility, Exploration and Anxiety Levels of Hatchery-reared Fish
Open Access
- Author:
- Giralico, Leah Catherine
- Area of Honors:
- Veterinary and Biomedical Sciences
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Victoria Anne Braithwaite Read, Thesis Supervisor
Dr. Lester C Griel Jr., Thesis Honors Advisor - Keywords:
- enrichment
hatchery
agility
exploration
trout
fish
novel object - Abstract:
- In an attempt to battle the negative effects of habitat degradation and over-exploitation on wild fish populations, researchers have begun to look to hatcheries as a component of ex-situ conservation. Hatcheries are utilized as breeding grounds for fish, which are ultimately released as a way to bolster and help maintain wild populations Unfortunately, released fish often display behavioral deficits and are unable to function as effectively as their wild counterparts, with large proportions of released fish lost to mortality. It is hypothesized that poor post-release survival arises because of adaptation to captivity, relaxed natural selection in the captive breeding environments, and the experience of being maintained in a safe, unchanging captive environment. This thesis project examined the potential benefits of environmental enrichment in a captive breeding environment on the behavior and swimming performance of rainbow trout (Oncorhynchus mykiss). Trout aged 11 months, were exposed to environmental enrichment by adding and exposing the fish to different kinds of novel objects, such as plastic models of aquatic weeds, PVC pipes, and floating plants that provided the fish with areas to explore, hide and interact. After two months of enrichment, the fish were tested in an Open Field Novel Object Test to assess their explorative nature, levels of anxiety and their overall swimming agility. These assays revealed that compared to fish reared in standard hatchery conditions, the trout reared in enriched conditions showed a lower level of anxiety and a higher level of activity. The enriched fish were also more explorative, but there were no clear effects on swimming performance and the fish were not significantly more agile in terms of the number of collisions the fish made within the test tank walls.