Document Type

Dissertation - Open Access

Award Date

2018

Degree Name

Doctor of Philosophy (PhD)

Department

Natural Resource Management

First Advisor

Brian D.S. Graeb

Second Advisor

Mark J. Fincel

Keywords

fisheries, walleye

Abstract

Walleye Sander vitreus is among the most popular sport fishes in North America and is the most sought-after fish in both South Dakota and North Dakota. Lake Oahe, a large main stem Missouri River reservoir, spans state boundaries and provides one of the most popular and productive Walleye fisheries in both Dakotas. The Walleye population of Lake Oahe has experienced wide fluctuations in abundance and size structure over the last 25 years which has caused high variability in angler use and satisfaction. Much of this variation is thought to be driven by Rainbow Smelt Osmserus mordax, which are the dominant prey for Lake Oahe Walleye and are characterized by erratic population dynamics. Rainbow Smelt in Lake Oahe are also prone to high entrainment rates during periods of high discharge. Twice during the last 25 years greater than 90% of the Rainbow Smelt population in Lake Oahe was lost due to high entrainment. I utilized long-term monitoring efforts by the South Dakota Department of Game, Fish, and Parks and assisted with a 5-year tagging study to research several components of the Lake Oahe Walleye fishery. Specific research areas included recruitment, movement, natural mortality, and fishing mortality of the Walleye population. I also studied the impact of Walleye population variability on angling. Throughout my research I paid special attention to spatial variation in the Lake Oahe Walleye fishery. I demonstrated that Walleye recruitment in Lake Oahe is consistent but variable and has been regulated by density independent factors over recent decades. Analysis of tag recoveries showed that Walleye movement in Lake Oahe is related to the configuration of spawning and feeding areas and spatial structuring forms relatively isolated groups within the reservoir. I found that angler catch rates of Walleye in Lake Oahe were independent of abundance but were strongly influenced by condition with highest catch rates occurring when Walleye condition was low. I also documented spatial variation in natural and fishing mortality of Walleye following high entrainment of Rainbow Smelt during 2011. Taken together, my results add to the understanding of Walleye fishery dynamics in Lake Oahe and how those dynamics respond to highly variable climatic, hydrologic, and biotic conditions. Evidence of spatial variation in Walleye population dynamics should be particularly relevant to managers. In addition to providing guidance to management of Lake Oahe, my results are relevant to broader topics such as Walleye fishery dynamics, reservoir ecology, and spatial structuring of freshwater fish populations.

Description

Includes bibliographical references

Format

application/pdf

Number of Pages

163

Publisher

South Dakota State University

Rights

In Copyright - Educational Use Permitted
http://rightsstatements.org/vocab/InC-EDU/1.0/

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