2005-05-27 / News

Lake Huron Goes ‘Back to Nature’ as Native Fish Species Rebound

By Amy Polk

  • Anglers fishing in Lake Huron can expect to catch smaller and leaner salmon for years to come. They also will find more of the kinds of species that once ruled the waters before exotic fish invaded the Great Lakes. Populations of alewife, the primary forage fish for salmon, have crashed, leaving millions of salmon struggling to find a meal.
  • Lake trout, yellow perch, walleye, and other native species are expected to become more abundant as the Chinook or "King" salmon, which has been the lake's predominant predator since the 1960s, become fewer and smaller. Pacific salmon, such as Coho and Chinook salmon, were introduced to the Great Lakes 40 years ago to control invasive alewives while creating a sport fishery. By the 1960s, as alewife populations climbed and the invasive sea lamprey killed the lake trout, the lakes had virtually no sport fishery.

    Stocking salmon killed two birds with one stone: It cut the number of alewives, which by then comprised 90 percent of the biomass of the Great Lakes. It also launched the rise of a great sport fishery that renewed anglers' interest in the Great Lakes.

    "It was a combination that fed a $1 billion fishing industry," said Jim Johnson, manager of the Department of Natural Resources' Alpena Fishery Research Station. "We could not have had any idea what would happen next."

    Mr. Johnson was speaking to a group of about 50 in Cheboygan on Thursday, April 21, at one of six informational presentations about Lake Huron's present and future status. The last report was Saturday, April 30, in Oscoda.

    The crux of Mr. Johnson's message was that anglers may no longer see the 20- to 30-pound Chinook in Lake Huron. Salmon here are already showing signs of malnutrition, and many have headed to Lake Michigan to find alewives.

    Based on what they now know, anglers can expect salmon around 10 pounds or lighter, and a more diverse fish population, Mr. Johnson said. What was once an artificial system, dependent on two exotics, the alewife and salmon, may be reverting back to a more natural fishery.

    Biologists, however, seem stumped by what the future holds and how to manage it. They are looking for guidance from public opinion and nature.

    "We used to play God on Lake Huron and we can't do that anymore," Mr. Johnson said. "I think it will become more like Lake Superior, where we can regulate it and nudge it a little, but we can't control it. Too many things have happened."

    Alewives in Decline

    Alewives, a small, silvery ocean fish, entered the Great Lakes by traveling down the St. Lawrence Seaway from the Atlantic Ocean, then through the Welland Canal, a manmade link between lakes Ontario and Erie. Conditions in the Great Lakes were perfect for the proliferation of alewives. By the 1960s, they had almost no natural predators. The lakes' main predator, lake trout, were nearly wiped out by over fishing and the sea lamprey. Lampreys penetrated the upper Great Lakes via the Welland Canal, from Lake Ontario, where they have always been present. Alewives grew in such numbers that other fish species comprised only about 10 percent of all the fish in the lakes.

    Once thought harmless, biologists now believe alewives prey on native species like young perch and walleye. They also cut the survival rates in the predatory fish that eat them by causing early mortality syndrome (EMS). Alewives contain an enzyme that destroys thiamin, an essential nutrient needed for the survival of young fish.

    In the mid-1960s, former DNR Fisheries Chief Howard Tanner devised a salmon stocking program that would take advantage of the ready and seemingly endless food supply available to them. Pacific salmon collected from the West Coast were introduced to the lakes, and the returning adults began a stocking program that pumps up to three million hungry salmon into Lake Huron every year. Lakes Michigan and Huron together receive nine million salmon each year.

    Alewives and rainbow smelt, another exotic fish, replaced native herring and other native minnows as the preferred prey fish for Lake Huron's larger predatory fish. By the late 1980s, alewives became Huron's dominant prey fish. Alewives are the favorite food of Chinook salmon, but since 1997 have been declining in number owing to a number of factors, Mr. Johnson said. Harsh winters caused huge die-offs. Exotic zebra and quagga mussels are trapping most of the nutrients once available to alewives at the bottom of the lakes, and predation on alewives by salmon has increased substantially.

    By 2004, biologists declared the Lake Huron alewife population had "collapsed completely," Mr. Johnson said.

    "No biologist working around the Great Lakes ever anticipated that alewives would collapse, and no biologist ever anticipated the natural Chinook reproduction like we've had here," said Greg Wright, a member of the Lake Huron Technical Committee which recommends management action for the lake. "Basically they've done a great job doing what they were initially supposed to do: control alewives."

    Mr. Wright serves on the Lake Michigan Technical Committee, Great Lakes Fish Health Committee, and has been the fishery enhancement coordinator for the Tribal Nunn's Creek Fishery Enhancement Facility since 1988.

    He believes the only way the lakes will stabilize from their present "boom and bust" situation is to allow native fish species to recover. He is encouraged by the natural recovery of lake trout, which are surviving much better as a result of effective sea lamprey control and management actions taken after the 2000 Consent Agreement between American Indian tribes and resource managers. They also adapt better to the food sources naturally provided by the Great Lakes, particularly those on the bottom of the lakes.

    "The only way to get stability is to have native species," he said. "I think the managers need to reconsider the policy of focusing management primarily on Chinook, and pay more attention to other native species."

    Salmon Stocking is Remarkably Successful; Most Salmon are Now Wild

    "We used to stock millions, but we can't do that anymore," said Department of Natural Resources Lake Huron Manager Dave Borgeson, speaking to the group in Cheboygan April 21. "The lake is really in control. The lake is telling us what to do."

    Perhaps the biggest surprise of the salmon-stocking program is the fact that most Chinooks in Lake Huron are wild fish, and reproducing without the help of humans.

    Biologists initially thought the salmon planted in the Great Lakes would not successfully reproduce, and they have been stocking every year to replace those that die or are caught. Now they have found that more than 80 percent of Lake Huron’s Chinook salmon were born in the wild rather than hatcheries.

    "Chinook began to reproduce in a big way, in a way that we never expected," Mr. Johnson said. "In 1992, only 15 percent of the fish were wild, and now 87 percent of Lake Huron's salmon were reproduced in the wild."

    Lake Michigan's salmon are 50.4 percent wild.

    Wild salmon spawn in streams and spend most of their adult lives searching for food in open water environments like oceans or the Great Lakes. The only time they return to streams is to spawn. Many raised in hatcheries and released in the Great Lakes have now strayed into suitable streams and are finding their own spawning grounds.

    "The fish we’re catching aren't going back to the hatcheries, they're going to Canada," Mr. Johnson said, noting that 80 to 97 percent of the wild fish were produced in Canadian streams around Georgian Bay and the North Channel.

    This baffles biologists, Mr. Johnson said, because they previously believed salmon always return to the stream of their "birth" to reproduce. At the same time, the artificially stocked salmon are not surviving as well as the naturally reproducing fish.

    "Ten percent of all salmon are dropping out of the system every year, and we're not seeing stocked fish survive like they used to," Mr. Johnson said.

    Perhaps the future of a salmon fishery lies in wild stock.

    Mr. Wright said the recent data suggest more than 12 million wild salmon are entering the lakes to join the three million stocked salmon every year.

    "That's the magnitude of this natural reproduction," Mr. Wright said. "So now we're looking at why we're even stocking."

    The Lake Huron Technical Committee has recommended periodic breaks from stocking to reduce the number of salmon competing for limited food. It also wants to take a closer look at how many salmon still need to be stocked, now that nature is taking over.

    Salmon Fishery Suffers as Alewives Disappear; Native Fish May Provide New Opportunities

    The salmon glut and demise of alewives has produced smaller and leaner salmon. Fisheries biologists are finding many in an emaciated state, but most of the anglers at the April 21 meeting in Cheboygan said the fish they are finding are small, but not starving.

    Norm Perkins of Les Cheneaux Islands Charter Tours said his customers caught plenty of salmon last year, though they were much smaller than in previous years. He is not as worried about lean fish as he is about predictions of utter disappearance of a fish that has kept his customers captivated. For five years, the Chinook “King” salmon has made up the majority of what his customers catch.

    "People were happy last year with the charters. They don't have to catch large fish to be happy," he said. "But it scares me a little bit as a charter captain. I like to have fish for my customers to catch. I would like to see the Lake trout pick up, and I hear they're getting good catches down south of here."

    He attended the meeting in Cheboygan, as well as other informational meetings on the status of Lake Huron. He believes the DNR is doing a good job of informing people, and he has hope in their predictions that other prey fish like herring, smelt, and native minnows will replace alewives, and other predators will join the salmon.

    "This is my sixth season, and when I first started five year ago, we used to get two or three 20-pound salmon early in the tour," Mr. Perkins said. "There used to be clouds of baitfish that went 60 to 70 feet down in the water. Now you see almost nothing. I think the salmon have done a pretty good job of controlling the alewives, and so have the cormorants."

    Mr. Perkins recalled a biologist telling him that alewives comprise nearly 50 percent of the diet of double-crested cormorants in the Les Cheneaux Islands. Both alewives and cormorants have been blamed for plummeting yellow perch populations. DNR Research Biologist Dave Fielder said alewives have long been known to prey on young perch, while his research implies that perch are recovering in the wake of cormorant control.

    Mr. Wright also suspects cormorants love the Les Cheneaux Islands because of the ready supply of alewives and perch.

    "If you get rid of the alewives, you'll probably get rid of the cormorants," he said.

    If native fish like perch, walleye, herring, and lake trout recover, Mr. Perkins believes he will have other fishing opportunities to offer his customers, if the salmon fishery does not.

    "I'm not going to worry about it. If we lost the Kings, I've already talked to my family about it, and we'll move into the St. Marys River to fish walleye, bass, and what the river has to offer."

    He is finding Atlantic salmon around the River, which he said are an exciting fish to catch, much like Chinooks in Lake Huron. One of his tour operators, Ken Drenth, caught a 15-pound Atlantic that won a Michigan Master Angler Award last year.

    Salmon are a lively fish that fight and jump around when they are caught, making them more appealing to anglers. Lake trout don't have a lot of fight in them, but their size makes them appealing. Mr. Perkins' customers were catching many nearly two feet in length last year, but they had to release most of them because of strict regulations designed to protect the trout as they recover. Some anglers are calling for fisheries managers to relax regulations so they will have more sport fishing opportunities in the future.

    "The jury is still out, but it appears likely native species like yellow perch and walleyes and lake trout, maybe lake herring, will rebound in the absence of alewives," Mr. Johnson said.

    Mr. Johnson said the alewife decline "probably just means smelt, which used to be the mainstay of the salmon and trout fisheries, will recover its former role."

    "But this will take a year or two," he added. "Meanwhile, predator fish, especially Chinook salmon, will have to adjust to prey scarcity. It appears we have little choice. Nature has taken its course and there appears to be little we can do to intervene."

    Future of Lake Huron is Uncertain; Biologists Consider Options

    DNR biologists paint a picture of Lake Huron that shows a future system resembling what it looked like more than a century ago. They are counting on their suspicions that alewives have suppressed native species’ ability to reproduce and grow. They hope smelt and traditional prey species like herring, chubs, and native minnows will provide the necessary nutrition to support traditional predators like lake trout, burbot, pike, musky, bass, and walleye. They are banking on lake trout playing a greater role in the future of sport fishing. The trout is now making the first meaningful recovery since sea lamprey control was started in the St. Marys River in 1999. Though the trout have also been lean lately, biologists expect they will adapt better to Lake Huron's conditions than the Chinook have.

    "They are a long-lived species that don't use as much energy as Chinook, and have plenty of time to grow," Mr. Wright said. "They were built for this Great Lakes environment. Without alewives, they will eat sculpins and other native prey."

    If their theories come to pass, Lake Huron will become a healthier system, similar to the one that took care of itself before exotics invaded the waters.

    The lakes are forever changed by exotics, however, and without regulating what comes into the Great Lakes by ballast water or through canals, natural species will forever be adjusting to new residents. There are now at least 180 exotic species in the Great Lakes.

    Two exotics, the zebra and quagga mussels, have been blamed for sucking much of the lakes' nutrients to the bottom, where alewives and salmon don't feed.

    "Their roles are only now beginning to be recognized," Mr. Johnson said. "It will take years of more study to measure just how much these invasives have affected alewife and Chinook declines. I feel that when the results are in, the role of invasive mussels will prove to be very large indeed."

    An important, tiny crustacean called the Diporeia helped bring nutrients to the middle of the lake by feeding on plankton that settled on the bottom. Diporeia were a favorite food of alewives and whitefish, but now they have disappeared from many of the lakes.

    "Diporeia thus acted as a mechanism for recycling settled nutrients back into the mid-water food chain, enhancing production of species such as alewives and Chinook salmon," Mr. Johnson said.

    The DNR's only options are to change regulations or change stocking, he added. The DNR has considered reintroducing the native lake herring where it has been absent in Saginaw and Thunder bays; or taking a strong position for controlling ballast water discharges from ships and boats.

    "No matter what the managers do now, the recent ecosystem changes that have occurred are so big the system's going to right itself," Mr. Wright said. "Lake Huron is a Great Lake that's been really turned upside down. It will be really interesting to see what happens this year. Fisheries biologists from all over the Great Lakes are watching very closely."

    Return to top

    Click here for digital edition
    2005-05-27 digital edition