Discovering the Source and Characteristics of an Unmanaged Population of Walleye (Sander vitreus) in a Recovering Urban Lake

摘要

Onondaga Lake is a recovering urban lake located in central New York State, within the city limits of Syracuse. A long history of perturbation is ending, as lake-wide remediation efforts are concluding. This once hypereutrophic lake is now classified as mesotrophic. One lingering issue is that elevated contaminant levels are trapped within the food web. The Walleye (Sander vitreus) is a popular sportfish throughout North America and central New York. Contaminant levels are still too high for consumption. Onondaga Lake is connected to other popular Walleye fisheries in central New York, and exchange of Walleye between lakes has been documented. Onondaga Lake does not receive direct stocking of Walleye, and there has been no natural recruitment documented in more than half a century. It its hypothesized that Onondaga Lake Walleye leave the Lake during the spawning season and eventually return. This study focused on assessing the population characteristics, obtaining a population estimate, and discovering the nursery habitat(s) of Onondaga Lake Walleye using mark and recapture techniques and otolith microchemistry. The density of adult Onondaga Lake Walleye in 2016 was estimated to in 232.9 Walleye/km2. The results indicate that the population Onondaga Lake Walleye is comprised of multiple sources. It is probable that high abundance of prey attracts Walleye to Onondaga Lake, even though spawning habitat still appears unsuitable. This research provides the information necessary to make management decisions on an urban Walleye population that is derived from external sources.