By Erich Luening
Staff at the Wild Rose State Fish Hatchery in Wisconsin began assessing a new manufactured feed on a test group of muskies to explore the health benefits of alternative nutrition and the potential to reduce rearing costs.
At the hatchery one group of Muskies was fed the traditional diet of zooplankton and minnows. A second group was fed manufactured fish food for the first part of their stay, and minnows for the remaining 60 days before being stocked into state waters.
“Feeding the muskies manufactured food is cheaper than collecting or buying minnows and there is no risk of introducing parasites or diseases that can come with minnows,” hatchery superintendent Steve Fajfer explained when he announced the program.
Under current methods, musky fry are fed on a completely live diet of zooplankton and minnow until they are big enough for release but it’s more expensive than using manufactured feed for part of the process.
Fajfer believes that adding the minnows back to the live diet for the last 60 days prior to release, will increase muskies’ growth and coloration and will also prepare them for what they will be eating once they are stocked into state lakes.
Fajfer also explained that the big issue is getting the muskies ready for their first winter. "If we can get them through this and still maintain good growth and survival in the long term, we feel we can save the state money by producing more muskies on the same budget."
Before the fish are transferred to their new homes, DNR staff will mark them with a fin clip that will distinguish one group from the other. In subsequent years state researchers and managers will be able to assess the survival rates of both groups of muskies.
Mike Staggs, DNR’s fisheries director, states that the experiment is made possible by the recent renovation of the hatchery and its increased capacity to raise fish on manufactured food.
“We estimate we can save 15 to 30% of the cost of raising musky by starting them on artificial feed, but we need to see whether the fish grow to an acceptable size and survive after stocking before we adopt this as standard practice at all hatcheries,” he said.
Raising a musky to stocking size – 10 to 12 inches or what’s known as a “large fingerling” size – is estimated to cost $10 to $11 a fish, recent DNR estimates show. That includes food, labor, hatchery overhead and the cost of retiring debt from recent hatchery construction and renovation.
The Wild Rose Fish Hatchery construction and renovation project, completed in 2008 at a cost of US$34.9 million, includes a new visitor center and two 300-gallon tanks where various species raised at the hatchery are visible to visitors. Other species raised are walleye, northern pike, and lake sturgeon.