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Office of Applied Science

Understanding trends and responses to and predator populations in Wisconsin lakes

This study assesses trends in Wisconsin’s panfish populations and their responses to angler exploitation and predator management to quantify their impacts on panfish abundance and size structure.

TIMELINE DNR PARTNER BUREAU Launch: July, 2019 Management Completion: June, 2022 EXTERNAL STAKEHOLDERS Great Lakes Indian and FUNDING Key Points Federal Aid in Sportfish Wildlife Commission »» Significant knowledge gaps exist in our Restoration USGS understanding of how panfish populations respond to regulation changes, panfish removals Panfish are some of Wisconsin’s most abundant and popular or promotion of predators. This project aims to fill in those gaps using population surveys, sport fish. , , black and yellow angler creels, and experimental field studies. comprised 75% of the total fish harvested from Wisconsin lakes in »» We expect that population trends will vary the past decade. among panfish species (e.g., bluegill and black crappie populations will be stable, while yellow Currently, panfish management is complicated by unexplored perch populations decline). relationships between population characteristics (abundance, »» We hypothesize that panfish anglers will size structure), anglers, predators and environmental influences. maintain catch and harvest rates across large This project seeks to disentangle these issues by comprehensively gradients in panfish abundance (i.e., will be characterizing panfish populations, their responses to panfish and hyperstable), and that anglers will be selective for larger panfish when lakes with gamefish management, and angler exploitation. smaller .

We will use a combination of standardized survey data and angler »» This project will also analyze environmental variables like water temperature, lake size, data to examine trends in population abundances, catch and water clarity on recruitment, rates, and harvest rates, and test for relationships with angler offering predictions for their future behavior or predator abundance and management practices. Our sustainability. results will be used to offer suggestions to address management »» We predict that predator management (e.g., issues. Additionally, this study will expand upon an experimental stocking, largemouth regulations) will be related to panfish size structure and regulations project currently underway to understand how abundance under some conditions and will exploitation affects panfish populations, helping managers to evaluate how predator management could be implement appropriate regulations to promote quality and effectively used to promote robust and resilient panfish populations. sustainability into the future.

SPOKESPERSON Zachary Feiner Natural Resources Research Scientist [email protected] (608) 221-6331