DNR to Stock More Brown Trout and Steelhead in Lake Huron
April 23, 2009
By now, most anglers on Michigan's Sunrise Side are aware the chinook salmon fishery in Lake Huron is not what it was just a few years ago. Although some respectable catch rates continue in some of the lake's more northern ports, salmon fishing in the southern end of the lake is almost nonexistent.
The food web has changed dramatically because of the arrival of exotic species -- zebra and quagga mussels, gobies, etc. The energy that formerly sustained the alewife forage base is being used up elsewhere. With the shift to a more near-shore-oriented food base, the prospects for chinook recovery any time soon do not appear to be bright.
In an attempt to restore Lake Huron's salmonid fishery -- especially in the southern end of the lake -- the Department of Natural Resources plans to change its stocking regimens for other species, most notably brown trout and steelhead, which are better able to utilize the near-shore prey base.
Let's start with brown trout. They are far more near-shore oriented than chinook salmon and can do well with a near-shore prey base.
"Unfortunately, our typical spring fingerling plants have been heavily predated upon by cormorants as well as other near-shore fish species," said DNR Lake Huron Basin Coordinator Kurt Newman. "So, instead of planting spring fingerlings, we plan to shift our efforts to planting fall yearlings."
Beginning this fall, Newman said the DNR will attempt to stock fish that measure about 10 inches and "we'll put them in the lake after the cormorants have migrated out of the area for the winter."
But, because of limited hatchery space, the DNR Fisheries Division will be able to raise only about a third as many brown trout for stocking. Instead of planting 260,000-280,000 brown trout, the plan is to stock about 85,000 browns in five locations.
Fisheries personnel already have begun preliminary creel-census work to help determine returns from spring fingerling stockings. The goal is to experiment with the fall yearling stockings for three years and assess the return rates of brown trout to the creel.
Steelhead, which roam more than brown trout, typically live higher in the water column than chinooks. Steelhead also are more able to take advantage of near-shore prey (such as mayflies) than chinooks. But, like browns, they are subject to heavy predation when they smolt. So the DNR plans to convert some of the net pens, once used for chinooks, into steelhead production.
According to Newman, the DNR will produce 120,000 steelhead for Lake Huron from the Thompson State Fish Hatchery next year. About half of them will be raised to smolt size stocked as usual, but the DNR plans to transfer the other 60,000 to net pens at Harbor Beach.
"The plan is to hold those fish until they are larger and release them later in the season, perhaps short-circuiting some of the predation they suffer," Newman said. "This strategy appears to be paying dividends in New York."
Again, it's the DNR's intention to use the net pens for three years and then assess the merits of the stocking change.
Meanwhile, the DNR hasn't forgotten about lake trout, which is doing well.
Fisheries managers are assessing different strategies for lake trout stocking, including "pulse stocking" of lake trout: The DNR would not plant lake trout at the same location every year, but rotate planting locations, giving planted lakers an opportunity to mature without stocking additional year-classes on top of them. The idea is that pulse stocking could result in a larger percentage of the planted fish reaching maturity.
Despite the decline in the chinook fishery, a couple of important native species -- walleye and perch -- are on the rise.
Walleye fishing is outstanding in Saginaw Bay and the fishery appears to be spreading along the Lake Huron lakeshore, notably on the southern end of the lake. And although the perch fishery is not especially shiny in Saginaw Bay, there has been a dramatic improvement in the perch population in the northern end of Lake Huron, in part, the DNR believes, because of cormorant-control programs.
In addition, DNR's experiments with native lake herring (cisco) production show it may be feasible to attempt to rehabilitate these populations in some areas of the lake that traditionally held them, but where they have virtually disappeared. Such a program would not only revitalize traditional near-shore recreational fisheries -- in places such as Thunder Bay and Saginaw Bay -- but ciscoes also could potentially serve as a food source for the larger salmonids, replacing the alewives in the food chain. Although the DNR currently does not have hatchery space to begin a lake herring-rehabilitation program immediately, the agency is investigating potential funding sources.
"Because of the changes in the food web, Lake Huron is wide open for us to try things," Newman said. "We have the opportunity to look at what the ecosystem is providing, then conduct appropriate large-scale management experiments."
Lake Huron's aquatic community and recreational fishery look very different today than they did only a decade ago. Odds are, they will look different in another decade as well. But the DNR's goals for Lake Huron remain the same: to maintain a healthy, balanced aquatic community and provide an excellent recreational fishery.