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Tuesday, January 30 • 10:40am - 11:00am
WALLEYE & PERCH: Changes in Yellow Perch Recruitment in Relation to Walleye Abundance in Green Bay

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AUTHORS. Iyob Tsehaye, Wisconsin Department of Natural Resources

ABSTRACT. Over the past decade or so, yellow perch and walleye populations in Green Bay have experienced fairly contrasting trends in abundance, with walleye numbers increasing and yellow perch numbers sharply declining. Changes in young-of-year, age-1, and age-2+ yellow perch abundances from 1985–2016 (estimated using a statistical catch-at-age model) were assessed in relation to changes in walleye abundance indices, and results showed that while there were no clear temporal patterns in young-of-year yellow perch numbers in Green Bay, annual age-1 and age-2+ yellow perch abundances were highly correlated with walleye numbers (r2 ≥ 0.60). Although correlation does not mean causation, walleye predation has been hypothesized to represent a potential recruitment bottleneck for yellow perch populations in the Great Lakes. Available – albeit limited – diet data and anecdotal information on these species from around the Great Lakes also imply that the contrasting abundance trends may be due to predatory interactions between these two species. As a first step to determine the extent of walleye predation on yellow perch in Green Bay, diet analyses were conducted in 2016–2017 on walleye samples from the bay. Preliminary results showed over 60% of walleye diets were composed of gobies, while yellow perch made up <10% of walleye diets depending on season. Although yellow perch account for a relatively small proportion of walleye diet in Green Bay, the relatively large walleye population may still impose a considerable predation pressure on the yellow perch population. As a next step, we will be combining results of walleye diet analysis with estimates of walleye population abundance from a statistical-catch-at-age model to quantify yellow perch mortality due to walleye predation in the bay.

Tuesday January 30, 2018 10:40am - 11:00am CST