by Chelsey Blanke
Last week, students in UW-Madison’s Ecology of Fishes lab course had the privilege of visiting WDNR’s Nevin Fish Hatchery, just a 15-minute drive from campus.
Field trips are a major component of the course’s content and this was the first time it’s included a hatchery tour. Fish hatchery and stocking operations are an important part of how fish are managed in Wisconsin and what better way to learn about this specialized role than from the experts who work there? Hatcheries around the state rear a handful of species, including muskies, northerns, walleye, sturgeon, and others. But at Nevin, it’s all about trout.
The Nevin Fish Hatchery was founded by James Nevin in 1876, and it is the oldest in the state. Nevin and others had observed that trout were disappearing from Wisconsin’s streams, the result of increasing agricultural erosion leading to rising water temperatures, so the cold spring waters in the Nevin Springs Fish and Wildlife Area made it the perfect place to set up shop. The water is typically around 50-52°F. It never freezes and tendrils of steam can often be seen rising off the pools in winter. In the early days, streams around the state were stocked by train and men carrying the fish to water in metal tanks strapped to their backs.
Three species of trout are raised there – brook, brown, and rainbow. Brook trout are native to Wisconsin, while rainbows and browns were introduced as an added opportunity for anglers when brook trout populations were in decline (the introduced species are also more resilient to environmental change).
There are some differences in how the three species are reared. Rainbows come from domestic stocks, meaning the hatchery receives fertilized eggs (in which you can already see the eyes of the baby fish!). The broodstocks of the brown and brook trout, however, are wild. As a result, hatchery supervisor Mike Aquino says brooks and browns are to rainbows what buffalos are to Black Angus. The buffalo and brown and brook trout are much more likely to survive and reproduce from year-to-year when turned-loose.
The Nevin hatchery was the first to develop methods for spawning wild trout and their methods have been adopted by hatcheries around the US and other parts of the world. In the fall, hatchery staff spawn fish remotely, at stream sites around the region, and from their captive broods.
Eggs are cared for in special incubation jars, in which continuous water flow keeps them moving to prevent the development of fungus and other fish diseases like ick. Once hatched, the fry are moved to another building where they feed on their egg sac until their digestive tracts are fully developed. They’re then fed until spring, when they’re large enough to be stocked in the wild.
Though tens of thousands of trout at different life stages may be housed at Nevin and stocked each year, the hatchery only has five employees. We were lucky enough that each one of them participated in giving our tour. Aquino always finishes his tours with the same important message, and one I echo here. Wisconsin fisheries management, including stocking programs, is funded by the sale of fishing licenses and is therefore entering uncertain times. License sales are in decline.
“In the past, we didn’t have to worry because retiring customers were always replaced by new customers,” he says. “If you’re an angler, try to introduce young people to fishing and fishing tradition. You don’t have to spend a lot of money, buy a boat, or catch a trophy. If you want, it doesn’t even have to be about fish – it can be about making memories and spending time with family and friends.”