Angler exploitation of an unexploited walleye population in the northern Great Plains.

Walleyes Sander vitreus are an important sport fish found throughout the northern Great Plains of North America. Periods of increased precipitation across the Great Plains can result in new or expanded lakes that contain unexploited fish populations. We assessed angler exploitation of a previously unexploited walleye population to estimate exploitation rates, subsequent changes in walleye abundance, and changes in angler behavior. This research provides an opportunity to add to the limited body of information concerning walleye exploitation and exploitation of unexploited populations. Hazeldon Lake, South Dakota contained an unexploited walleye population and was opened to angling on 15 July 2006. Initial exploitation was high, estimates exceeded 16% after two days and 75% after 16 days. Anglers harvested an estimated 6868 walleyes during 15 July - 31 August 2006; this harvest represented 79% of the pre-opener population estimate of 8661. The 2007 spring population estimate was 2436 fish and represented a 72% decline from the 2006 estimate. Gill net catch per unit effort (CPUE) averaged 30.0 fish net−1 prior to fishing in 2006; the 2007 CPUE was 76% lower at 7.2 fish net−1. A lack of recruitment resulted in no substantial increases in relative abundance from 2007-2017. Fishing pressure was high when the lake first opened to fishing. However, the number of anglers and exploitation rates declined once walleye catch and harvest rates dropped off. Our results suggest that walleye populations in new or expanded waters located in the northern Great Plains can be extremely vulnerable to angling but when catch rates drop off few anglers will continue to fish a given water; instead moving to other waters potentially having higher walleye catch rates. [ABSTRACT FROM AUTHOR]