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| Here is an excerpt from Adam D. Nickel
Senior Fisheries Biologist – Bureau of Fisheries Management
on the trawling assessment on Lake Winnebago:Walleye
The 2016 YOY walleye catch rate was 9.9/trawl, ranking as the 7th highest catch rate
since 1986 (Figure 1). The 2016 catch rate was substantially higher than in 2014 (0.4/trawl) and
2015 (1.4/trawl), but comparable to strong year classes that occurred in 2011 and 2013. The
strong 2016 year class can likely be attributed to the high spring water levels observed on the
Wolf and upper Fox Rivers that led to favorable conditions on walleye spawning marshes. High
spring water levels provide spawning adult walleye access to suitable habitat, while also
providing adequate flows to keep eggs well aerated and flush out newly hatched fry. Besides
having favorable water conditions, walleye fry also need a good available source of zooplankton
for food to survive once they arrive in the upper pool lakes. Walleye fry survive off their yolk
sac during their first few days of life; however, once the yolk sac is absorbed their survival is
dependent on having a well-timed zooplankton hatch. Ultimately, Mother Nature is the major
driving force that dictates spring water levels, zooplankton availability, and other factors that
drive walleye year class strength on the system.
Although the Winnebago System experienced weak walleye year classes in 2014 and
2015, strong year classes from 2008, 2011, and 2013 continue to fuel a robust walleye fishery.
Favorable growing conditions (extended growing season and abundant forage) resulted in good
growth of fish from the 2016 year class (average length 6.9”), but this year class likely won’t
contribute to the fishery for another 2-3 years. Nearly 100% of male walleye reach maturity at
age 3, thus males from the 2016 year class will make their first spawning run in 2019. Female
walleye typically reach maturity between 4-6 years of age (~30% mature at age 4, 82% by age 5,
and 99% by age 6), thus females from the 2016 year class will spawn for the first time between
2020-2022. Although it will still take some time for females from this year class to reach
maturity, the majority of the 2013 females will mature and make their first spawning run in
2018. Stay tuned for the 2016 Winnebago walleye report for more details.
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