Date of Award
5-25-2024
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Biology
First Advisor
Melissa Wuellner
Committee Members
Keith Koupal; Mark Pegg
Keywords
fish; ecology
Abstract
Acoustic telemetry is a tool commonly used to better understand the fates of fish following a stocking event. Until recently, predation on stocked fish could only be inferred by observing and identifying abrupt changes in tag detection histories. Recently, a novel predation transmitter has provided better insight into how predation affects post-stocking survival. The main objectives of this study were to use these transmitters to 1) estimate predation rates on stocked juvenile Chinook Salmon in a landlocked system (Lake Oahe, South Dakota) and 2) estimate dispersal rates and residency times of the Chinook Salmon after stocking. Additionally, our secondary objectives were to determine how quickly predation was occurring, the time of day of predation events, if there were differences in size between predated and non-predated fish, and if there were differences in dispersal rates or residency times between predated and non-predated fish. In 2021 and 2022, we surgically implanted Innovasea® V5D – 180khz transmitters in 110 juvenile Chinook Salmon. These tagged Chinook Salmon were stocked in two locations on Lake Oahe along with a large cohort of untagged individuals. Across the two study years, we observed a mean predation rate of 32.9% on the tagged Chinook Salmon over a short time period (i.e., <9 days post-stocking). Predation on the tagged Chinook Salmon occurred soon after stocking with a mean time to predation of 86.7 hours. Additionally, 70% of the observed predation occurred during the daytime. Total length did not differ between fish predation outcomes of stocked fish, but total weight did differ between groups. Mean residency time across both years and bays was 80.9 hrs and mean dispersal rates were 101.3 m/hr. Our results could provide insight into recruitment bottlenecks within this population and provide guidance for future stocking strategies to ensure a better return on investment of this costly stocking program.
Recommended Citation
Gravenhof, Dylan Alan Jon, "Post-stocking predation and dispersal of stocked juvenile Chinook Salmon (Oncorhynchus tshawytscha) in Lake Oahe, South Dakota" (2024). Biology Theses, Dissertations, and Student Creative Activity. 17.
https://openspaces.unk.edu/bio-etd/17