According to the flyer below, a 6–12 inch walleye might be about 1–3 years old, while fish in the 21–25 inch range are estimated around 8–12 years old. Trophy-sized walleyes of 26–30 inches are listed at roughly 12–20 years, with fish over 30 inches potentially reaching 20 years or more.
Those numbers are useful as a general guide, not a fish birthday calculator. The flyer itself points out that growth varies with water temperature, food availability, genetics, sex, and the individual body of water. Scientific research backs up that caution. USGS has documented substantial differences in walleye growth among populations across North America. USGS walleye growth research
The flyer also notes that female walleyes generally grow larger and live longer than males, another reason two fish of identical length aren’t necessarily the same age. Washington fisheries research reports faster growth and larger maximum sizes in females. Washington Department of Fish & Wildlife
For a better age estimate, biologists can examine structures such as otoliths, which contain annual growth zones that scientists use to estimate a fish’s age. NOAA Fisheries: Fish Age and Growth
So, while the flyer is a handy guide for answering “about how old might this walleye be?” Just don’t turn those ranges into definitive rules.
A measuring tape gives you an educated guess. The fish’s biology keeps the better records.
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