What do sturgeon eat?

WLUK file image.

OSHKOSH (WLUK) -- Sturgeon in the Lake Winnebago system are feasting on a fish called gizzard shad, according to a Department of Natural Resources survey.

The DNR examined the stomachs of 87 fish speared this year -- 52 from Lake Winnebago and 35 from lakes Butte des Morts, Winneconne and Poygan. Of the Lake Winnebago fish, 71.2 percent had gizzard shad in their stomachs, while 82.9 percent of fish from the upriver lakes did. Sturgeon biologist Ryan Koenigs says that's no surprise, given the large hatch of gizzard shad the DNR observed in 2016.

In Lake Winnebago, the sturgeon were also found to be eating zebra mussels and lake fly larvae. In the upriver lakes, lake fly larvae were the only other food source found in sturgeon stomachs.

On average, speared sturgeon had 1.27 pounds of undigested food in their foregut, with 1.18 pounds of that being gizzard shad. The foregut is only part of a sturgeon's digestive system, so the sturgeon had more partially digested food elsewhere in their systems.

Koenigs says abundant gizzard shad make sturgeon healthy and plump, but the extent of the sturgeon population's health won't be known until length and weight data can be compared after the season closes on Sunday.

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