Wisconsin Natural Resources magazine

Wisconsin Natural Resources magazine

Photo of fisheries biologist with large lake trout © DNR Lake Superior Fisheries Team

Fisheries Biologist Mike Seider handles a large lake trout from Lake Superior.
© DNR Lake Superior Fisheries Team

October 2010

Recovery and redemption

Lake trout hold on as a prominent force in the Lake Superior fishery.

Lisa Gaumnitz

"The great abundance of fish and the convenience of the place for fishing have caused the Indians to make a fixed settlement in those parts. It is daily manna, which never fails."
– Antoine Cadillac, French explorer of the Great Lakes region and a founding father of Detroit, 1695
"What of the great lakes...And where are the fish?"
– Chicago Times, 1881

Coming just two hundred years apart, those quotes bookend the sobering story of the Great Lakes fisheries. These inland seas once teeming with whitefish, lake sturgeon, lake herring and lake trout were severely damaged by the carelessness, even ruthlessness of settlers and commercial fishing enterprises who used and abused the fisheries, says Margaret Beattie Bogue, author of Fishing the Great Lakes.

Now, a new chapter is being written. Lake trout, one of the four signal species in Cadillac's day are showing strong signs of recovery in Lake Superior, with Wisconsin waters boasting some of the strongest populations. That's good news for the overall health of the Lake Superior ecosystem and for anglers and commercial fishers.

In perhaps the most telling sign for the first time in a half-century, artificial stocking of lake trout has ceased in almost all parts of the lake. It's a direct and hopeful reversal of what Bogue says brought the fisheries down in the first place: overfishing, pollution, political squabbling among Great Lakes states and provinces, poor public policies, commercial exploitation and the kicker – rampant populations of an invasive species that literally sucks the lifeblood out of the fish.

"This is the greatest lake in the world and we brought its most important fish to virtual extinction. Now we've brought it back through everybody working together," says Mike Hansen, a University of Wisconsin-Stevens Point professor who is a commissioner on the Great Lakes Fishery Commission. "This is an enormous story that never gets appreciated."

The challenge is keeping the lake trout fishery strong, Hansen says. "One of the problems is that people now say, 'we want to fish Lake Superior harder. But what we know is we can crush it if we're not careful – the world's story is we've crushed fish populations time and again."

Matt Symbal, a fish and wildlife biologist for the Red Cliff tribe adds, "It's important for people to understand that the various agencies around the lake are constantly monitoring the lake trout and adjusting allowed harvests, but there's still a fine line where the fishery can slip. Everyone seems reluctant to say (the lake trout recovery plan) has fully met its mark."

A top predator brought low

Lake trout have long been critical to the health of the Great Lakes and its people. They are the top predator in "the big lake," keeping things in balance. They hunt independently and eat everything in sight. They consume both young and adult fish, but they are slow-growing and long-lived, and they don't need to eat constantly.

While whitefish have long been a more popular meal, lake trout have been a staple for people living along Lake Superior for thousands of years. Native American tribes fished for lake trout and other Great Lakes species before 3000 B.C. and have used nets to haul them in since about 300 B.C., according to Fishing the Great Lakes.

Jesuit missionaries described giant trout 50 to 90 pounds in the 17th century. The coming of European explorers, traders and missionaries in search of empire, wealth and Christian converts changed the patterns of subsistence culture somewhat in the 17th century and more so in the 18th century, Bogue writes. European policies encouraged U.S. and Canadian settlers to carve farms out of the wilderness as nations raced to expand their boundaries. Prevailing religious belief held that man had dominion over the land, water and their creatures, a departure from Native American concepts that man was a part of the ecosystem, not its master. Fish were considered a common public good, free for the taking. And the Great Lakes region was carved up into eight states and two provinces that precluded unified and effective regulation of the fisheries, Bogue writes.

Photo of Red Cliff Fisheries staff © Matt Symbal
Staff from the Red Cliff Fisheries lift nets, measure fish and take samples during summer surveys.
© Matt Symbal

Improvements in technology, boats, nets and other gear allowed commercial crews to fish more intensively. Harvests climbed from 39 million pounds of fish in 1874 to more than 146 million pounds by 1889. The great decline in fish stocks was on.

Lake trout lasted longer in the Great Lakes and particularly in Lake Superior for a variety of reasons. Their biological behavior – living in deeper water and living rather independently instead of in large schools – gave them far greater chances of survival than whitefish, which were preferred by commercial fishers and were found in big schools. The relative remoteness of Lake Superior meant it was the least polluted of the lakes.

But lake trout could not survive the sea lamprey, a parasitic, jawless, eel like fish native to the North Atlantic. The lampreys found their way to Lake Ontario in the 1800s, and reached the Upper Great Lakes in the 1930s after reconstruction of the Welland Canal in 1921 effectively removed Niagara Falls as a natural barrier.

By 1962, harvest of lake trout on Lake Superior had declined more than 90 percent from the previous decade, and the lake's management agencies closed commercial harvest. The era of plenty was over.

Partnerships to restore a fishery

The sea lamprey delivered the jolt jurisdictions needed. The Convention on Great Lakes Fisheries, between Canada and the United States ratified in October 1955, created the Great Lakes Fisheries Commission (GLFC) and gave it two charges: eradicate or control the sea lamprey and secondly, coordinate research and recommendations to sustain productive fish stocks shared in common.

Initial recovery plans focused heavily on stocking. By the 1960s, lake trout populations had increased sharply along the Wisconsin and Michigan shores, but not elsewhere. By the 1980s, abundance of stocked lake trout in Great Lakes waters off Wisconsin had declined due to increased fishing pressure, continued sea lamprey predation and reduced stocking rates, according to "A Lake Trout Restoration Plan for Lake Superior," produced by the GLFC and edited by Mike Hansen. That plan laid out a blueprint that moved away from relying on stocking and instead called for prudently managing the remaining wild fish.

Hansen explained the change in approach. When you first start out stocking fish, there are typically fewer predators and nothing to eat the fry. As the program matures, survival rates from stocking drop off as the number of adults increase. Fish stocked in later years have much lower survival rates and eventually no survival. In Lake Superior, we documented that decline, and by the time we drafted the recovery plan in 1996, we decided we needed to count on factors other than stocking to restore the fishery. Stocking in the Apostle Islands area was suspended. The commission's technical committee determined that to sustain the fishery, the annual lake trout mortality should not exceed 45 percent. The plan called for the agencies lakewide to reduce mortality due to sea lamprey, to better protect habitat for remaining wild trout, and to more tightly control the total harvest taken by anglers and commercial fishers.

That plan has been carried out in Wisconsin by the Department of Natural Resources, the Red Cliff tribe and the Bad River tribe, which collectively manage fisheries in state waters of Lake Superior, and by the U.S. Fish & Wildlife Service. The federal agency carries out lamprey control in U.S. waters as the agent for the GLFC. In the past USFWS also stocked lake trout in Minnesota, Wisconsin and Michigan waters.

"For 35 years, the parties have been able to find ways to manage the fishery, and it's generally been successful," says Wisconsin Fisheries Director Mike Staggs. "They have negotiated three 10-year agreements, and I think a lot of credit goes to the three governments for trying to avoid federal litigation."

Their collective success is distinct from managing inland fisheries, where federal courts had to intervene to resolve issues of Native American treaty rights in Wisconsin and other states.

Protecting remnant stocks of wild trout

The key to the lakewide recovery for lake trout lies in Wisconsin waters. "We have some of the best spawning habitat and natural reproduction in all of Lake Superior," says Mike Seider, DNR fisheries biologist in Bayfield.

In the 1950s, while lake trout populations crashed lakewide, remnant stocks persisted off Gull Island Shoal, Cat Island and Devils Island in the Apostle Islands in Wisconsin. The area continued to provide harbor and sanctuary for lakers that spawned on these shoals. "It was a matter of maintaining and continuing to build on those remnant stocks," Seider says. Two areas adjacent to those important spawning shoals were protected as fish refuges, both of which DNR continues to maintain.

The partners, with help from UW Sea Grant scientists, worked together to bolster natural reproduction by stocking fertilized eggs on Devils Island Shoal. The eggs were held in AstroTurf "sandwiches" suspended a few feet above the shoals. The AstroTurf protected the eggs from predators and allowed the fry to escape after hatching. The idea is that hatched fish would imprint on the shoal, and return to spawn one day. This biological head start seemed to have succeeded. Stocked trout had trouble finding the offshore reefs but fry raised in the AstroTurf nurseries successfully colonized them, Seider says.

"That really was a shot in the arm for the northern part of the Apostle Islands," he says. "Now there is a population of spawning adults building up with bigger fish showing up."

Wild trout caught in spring assessments increased from 30 percent of the catch in the 1980s to greater than 95 percent in 2006-2010, Seider says.

Hansen's studies are evaluating how effective the Wisconsin refuges are, and finding ways to better account for fish movements between management units so the harvest quotas can more accurately reflect the lakewide picture. "Without the Gull and Devils islands refuges, we couldn't afford to have the commercial fishery we do out there," Seider says.

Preventing overfishing

Managing the people who fish for lake trout is another critical factor in the species' recovery.

"The biology of lake trout works against us because they take 10 years to mature," Seider says. "They don't just come back in a year or two, so you have to manage very conservatively." The partners carefully monitor the fish populations each spring and fall, keeping close counts on harvests and feeding the results into computer models that estimate how many fish can safely be taken out every year. The total allowable catch in Wisconsin waters is divided among tribal commercial fisheries, state commercial fisheries, tribal subsistence fishers, and state sport anglers. Whitefish is the main target of commercial fishers, but lake trout are caught incidentally in their nets and provide income as well.

Photo of commercial fishing boat © Robert Queen
Commerical netters harvest lakers as an incidental catch to their main target – whitefish.
© Robert Queen

"Lake trout historically have been a primary food source for the tribe," says Symbal. "Right now it's of huge economic importance to Native American families. We have one of the largest commercial fisheries on Lake Superior, and families can also obtain a license to fish short small gill nets offshore for subsistence purposes."

Tribal interests receive 50 percent of the total allowable catch. The Red Cliff monitor and manage their own anglers, whether they are in Wisconsin or in Michigan, or as part of the ceded territory. Red Cliff Fisheries Department personnel are placed onboard some of the tribal commercial fishing vessels to count fish brought aboard the vessel. This data is used to estimate the accurate catch rate to provide adequate information for decision-making, Symbal says.

The Department of Natural Resources has allotted 75 percent of the state's portion of the quota to sport anglers, and 25 percent to commercial fishers. To ease pressure on the fishery, the state offered several commercial fishers incentives to retire operations in 1997, implemented more conservative harvest regulations on the remaining 10 commercial fishers, and set limits on the sport angler's harvest, including a three fish daily bag limit with only one fish over 25 inches in length.

"The result of cooperative fisheries management has been a gradual increase in wild lake trout abundance since the 1970s, but these population increases have leveled off recently," Seider says. In the mid 2000s, managers increased the quotas in response to the highest wild lake trout catch rates recorded in almost 50 years. "Then the population was fished harder, especially by commercial netters, and we had higher than expected mortality rates from sea lampreys," Seider says. The result was a drop in fish population.

So in fall 2009, based on projections, managers agreed to lower overall harvest by almost 32 percent over the next three years.

That big sucking sound

For fisheries managers, sea lamprey predation remains a big challenge to future lake trout populations, Symbal says. Though lampreys will feed on all species of large Great Lakes fish, they prefer trout and salmon. Lampreys attach to fish with a sucking disk and sharp teeth. They feed on the body fluids, scarring the host or killing it.

Considerable effort and expense has gone into trying to contain the losses, but, until recently, sea lampreys have killed more lake trout in Lake Superior every year than all commercial fishers and anglers combined.

The Lake Superior Technical Committee's goal is to suppress sea lampreys to levels that would cause only insignificant mortality of adult lake trout. That goal has only been met in the last two years, when spawning sea lampreys were estimated at fewer than 30,000, well within the 38,000 goal set for Lake Superior, according to Jessica Barber, fish biologist for sea lamprey control at the U.S. Fish and Wildlife Service's Marquette Biological Station in Marquette, Mich.

Wisconsin, unfortunately, contributes more than its fair share of sea lampreys, Barber says.

"We conduct lampricide treatments on about three to five Wisconsin tributaries per year. We also use traps and lamprey barriers."

The selective lampricide TFM remains the primary tool to control sea lampreys throughout the Great Lakes, supplemented in some areas by traps, barriers and the release of sterile males.

Lampreys are trapped on six Wisconsin tributary streams each year, and three Wisconsin tributaries have barriers built or modified to block migrating sea lampreys during their spawning runs.

The Great Lakes Fisheries Commission is borrowing techniques from the insect world by trying to harness the chemicals of love. Male lampreys shed pheromones when they are mating that attract females and the commission is experimenting to see if they can lure more sea lampreys to streams or traps baited with the scents. Once trapped, the lampreys can be killed or sterilized. If these experiments prove successful in steering lampreys to their death, control measures could become much more economical.

The stakes to find more cost-effective controls could rise as the temperature increases. Barber anticipates that both larval and parasitic sea lamprey growth rates may accelerate if water temperatures and the length of the growing season increase as a consequence of climate change.

Moving to the next phase

The continuing threat posed by sea lampreys, newer threats such as zebra and quagga mussels, and Asian carp poised to enter the Great Lakes, have Bogue feeling pessimistic about the fates of Lake Superior and its lake trout. Ten years after writing her book, and 50 years after ballast water was recognized as a major pathway for invaders, she's disgusted with the country's response to the menace.

"I look at this and I just groan. Have people learned anything at all? Do they understand what the results of this can be?"

Seider shares her concern about invasive species and fish diseases.

Seider is cautiously optimistic. "There are inherent limitations to this lake. We're probably never going to get back to where it was pre-European settlement. We've altered the system too much. But we're learning from our past mistakes.

"We'll probably have these ups and downs but as long as we can maintain these fish refuges, as long as we can protect healthy numbers of spawning fish, and continue to allocate and manage the fishery wisely, we can weather these downswings."

Lisa Gaumnitz is public affairs manager for DNR's Water Division.