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Tuesday, January 30 • 9:00am - 9:20am
WALLEYE & PERCH: A Multi-scale Approach to Identifying and Addressing the Causes of Minnesota’s Declining Yellow Perch Populations

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AUTHORS. Jeffrey Reed, Bethany Bethke, Michael McInerny, David Staples - Minnesota Department of Natural Resources.

ABSTRACT. Often considered a keystone species in north-temperate lakes, declines in the abundance of Yellow Perch in assessment netting across Minnesota have become a concern of fisheries managers.  Due to their ecological importance, we examined state-wide trends, individual lake case histories, as well as soliciting insight from fisheries managers to identify potential causes for the declines. Since 1970, state-wide decline, as measured by gill net catch per unit of effort, approximating 35% has been observed.  Individual case studies indicate that declines are likely the result of a combination of factors, including increases in water clarity, predator stocking, and the introduction of invasive species. In some lakes such as Carlos and Horseshoe, substantial declines began over 40 years ago. However in other lakes where none of those factors occurred and the declines are more recent, larger ecological drivers of change, such as watershed development and land use changes and climate change may be contributing to declines.  We used an influence diagram to solicit input from managers for potential causes for declines; allowing for the use of important localized knowledge about population declines.  Although the decline in Yellow Perch populations is generally a state-wide phenomenon, some populations are not demonstrating decline.  The scale of decline indicates this is a complex problem with no easy answers.  However, by comparing stable populations with those in decline, using state-wide data, individual case studies and manager input we look to address the causes of decline and offer suggestions for stabilizing or reversing that decline.  

Tuesday January 30, 2018 9:00am - 9:20am CST