What Happens When a Lake Trout Survives a Sea Lamprey Attack?

Study will help fishery managers understand more about Great Lakes lake trout populations

October 13, 2016
By Marie Zhuikov

Despite close attention by fishery managers, the lake trout population in the Wisconsin waters of Lake Superior has been declining in the past decade or so. Recently, this led to emergency limits on the number of lake trout that can be harvested by anglers and commercial and tribal fishermen in Wisconsin waters of the lake.

In an effort to get a better handle on population stressors so that more accurate fishing quotas can be set, fishery managers are looking at a variety of factors that might stress this important population. One of those things are attacks by sea lamprey – the eely vampire of the fisheries world.

Although the number of lake trout deaths by lamprey rank behind those from commercial fishing, natural causes and angling, it is estimated that more than 50 percent of lake trout attacked by lamprey survive. It’s long been assumed that lamprey-attack survivors suffer from impaired growth and reproduction rates, but this has never been studied in the lab.

Tyler Firkus, a fish and wildlife Ph.D. candidate at Michigan State University (MSU), plans to change that. However, first he has a few obstacles to overcome for this unique project. For instance: how to catch lamprey that are in the relatively short feeding stage of their life cycle, how to keep the lamprey alive until they can be introduced to lake trout, and how to expose the trout to lamprey parasitism just long enough so that it’s not lethal.

“It’s a major project with a lot of moving parts,” Firkus said. “There’s different hurdles and different things that keep popping up because nobody’s ever done this before.”

Of the various types of lake trout, Firkus is studying the siscowets (the fat ones) and lean lake trout. They were chosen for the study for comparison purposes. “There’s some evidence that the siscowet are more prone to parasitism from lamprey and they might actually be buffering the lean lake trout from parasitism,” Firkus said.
Why lamprey seem to prefer siscowets could be because lamprey like their fattier taste, or because they live in the same deepwater habitat that feeding lamprey prefer, or it could just be a numbers game because there are more siscowets in Lake Superior than there are lean lake trout, by a ratio of 15:1 (based on 2006-2011 data).

Firkus is conducting his research at the University of Wisconsin-Stevens Point Northern Aquaculture Demonstration Facility (UWSP NADF), a Wisconsin Sea Grant partner organization located in Red Cliff, Wis. The facility currently holds a mature broodstock of both trout types from previous research projects. The UWSP NADF is the only facility in the world that has domestically reared siscowets available. Firkus is just beginning what he suspects will be a four- to six-year project.
As for catching the lamprey, Firkus is getting help from commercial fishermen in the Bayfield area and from the Hammond Bay Biological Station in Michigan, which specializes in lamprey collection and research. So far, he has about 20 lamprey in their feeding stage, with hopes of capturing 30 to 40 total.

As for exposing the lamprey to the research fish, Firkus plans to do this is in a controlled manner, with one lamprey parasitizing one lake trout per tank. For scientific comparison, other lake trout will go into tanks without lamprey.

“We want to look at the sublethal effects of parasitism, “Firkus said. “If the lamprey parasitize longer than five days, it’s likely that the lake trout will die. We will remove the lamprey around three or four days to avoid mortality.”

After the lamprey are removed, he plans to study a number of physical parameters of the fish over the long term. These include growth, reproduction and immune response. He will divide his time between UWSP NADF and MSU depending on whether he needs to collect data, process data or teach.

“The data will be an important tool to refine current physiological and bioenergetics models to better predict how sublethal sea lamprey attacks can affect the lake trout population,” said Greg Fischer, UWSP NADF operations manager. “The information will be vital for proper management strategies in all the Great Lakes.”


Funding for the project is coming from the Great Lakes Fishery Commission. Project leaders are Cheryl Murphy, Michigan State University; Fischer, UWSP NADF; Rick Goetz, National Oceanic and Atmospheric Administration Northwest Fisheries Science Center; and Shawn Sitar, Michigan Department of Natural Resources Marquette Fisheries Research Station.

Ice cover delays stocking of some catchable trout

OSCEOLA - A late spring thaw is again delaying stocking of catchable trout in some northern inland waters, state hatchery officials say.

"This year we're again experiencing some delays in stocking due to ice cover in the northern part of the state," says David Giehtbrock, Department of Natural Resources statewide fish production manager. "As soon as Mother Nature thaws things out, we will get the rest of the fish into the water!"

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DNR stocks catchable size trout in inland waters where the habitat is marginal and there is no natural reproduction; such waters are a small subset of Wisconsin's more than 13,000 miles of classified trout water. More than 5,400 miles of trout water are Class 1, supporting naturally reproducing populations. Find forecasts for many of these naturally reproducing waters in the 2014 Wisconsin Fishing Report trout forecast.

This year, DNR had planned to stock more than 316,000 catchable size trout in dozens of inland trout waters across Wisconsin before the May 3 inland fishing season opener. Nevin State Fish Hatchery in Fitchburg has been able to stock all of the waters on their list, mostly more southern waters where the ice has been off for several weeks now.

However, some stockings are delayed of fish from St. Croix State Fish Hatchery and Osceola State Fish Hatchery, which supply fish mainly to northern waters. Stocking of brown trout will be delayed to Stormy Lake in Vilas County, brook trout to waters in Ashland, Bayfield, Oneida, Vilas and Waukesha counties, and to waters in Ashland, Florence, Iron, Oneida, Rusk and Sawyer counties. Bradley in Chippewa County and Camp Lake in Washburn County also will receive fish after the opener.

DNR fisheries crews have been raising the rainbow, brown, and brook trout at Nevin, Osceola and St. Croix Falls state fish hatcheries. They've also been working with fishing club volunteers, students, and others to help stock the fish raised under 21 cooperative rearing agreements with DNR.

More than 100,000 of the fish were stocked in urban fishing waters, small lakes and ponds cooperatively managed with the local municipality and used as a place for fishing clinics and kids fishing.

The rest of the trout are stocked in waters where the habitat is marginal and there is no natural reproduction. They are a small subset of the state's overall trout treasury - more than 13,000 miles of classified trout water and trout populations that have generally increased statewide over the last 60 years.

DNR plans to stock more than 316,000 catchable-size trout in inland waters

MADISON - More than 316,000 catchable size trout are being stocked in dozens of inland trout waters across Wisconsin before the May 3 inland fishing season opener. A list of waters receiving fish and how many were planned for stocking is now available online.

"Continuing ice cover on the lakes and difficult conditions at the lake access are delaying some of the planned stocking this year, but we're still hoping to have everything done by the May 3 opener," says David Giehtbrock, Department of Natural Resources statewide fish production manager.

"The upside is that while they wait to be stocked, these fish continue to grow bigger at our state fish hatcheries and will be ready for catching when conditions improve."

Go to the DNR website, dnr.wi.gov, and search keyword "fishing," and click on the trout stocking feature in the center of the page.

DNR fisheries crews have been stocking rainbow, brown, and brook trout raised at Nevin, Osceola and St. Croix Falls state fish hatcheries. They've also been working with fishing club volunteers, students, and others to help stock the fish raised under 21 cooperative rearing agreements with DNR.

More than 100,000 of the fish are to be stocked in urban fishing waters, small lakes and ponds cooperatively managed with the local municipality and used as a place for fishing clinics and kids fishing. Many of these waters have already been stocked, including for last week's free kids' fishing clinics held at 17 locations in southeastern Wisconsin.

The rest of the trout are stocked in waters where the habitat is marginal and there is no natural reproduction. They are a small subset of the state's overall trout treasury - more than 13,000 miles of classified trout water and trout populations that have generally increased statewide over the last 60 years.

Read "A Trout Treasury: Welcome to the good old days of trout fishing," in the April 2011 Wisconsin Natural Resources magazine to learn about the general, overall improvement in the total number of trout, and trout in all the size ranges since 1950.

Find links to downloadable and interactive maps of trout streams and other resources to help find places to fish on the inland trout page of the DNR website.

DNR stocks adult trout in southeast Michigan, creates additional fishing opportunities

The Department of Natural Resources' Fisheries Division recently stocked adult trout in the Clinton River at Riverside Park in Auburn Hills, Huron River at Proud Lake Recreation Area in Commerce Township, and Spring Mill Pond at Island Lake Recreation Area in Brighton.

The Clinton River was stocked with 600 brown trout from 15 to 17 inches; the Huron River was stocked with 1,800 brown trout sized 15 to 22 inches and nearly 1,400 rainbow trout sized 16 to 22 inches; and Spring Mill Pond was stocked with nearly 400 brown trout sized 15 to 22 inches and nearly 600 rainbow trout sized 16 to 22 inches.

This annual activity uses unneeded brown and rainbow trout broodstock from Michigan's state fish hatcheries to release in special regulation areas.

Huron River at Proud Lake Recreation Area is closed to fishing Oct. 1 through March 31. From April 1-26 anglers are limited to flies-only, catch-and-release fishing. Youth under the age of 12 may keep one fish between 8 and 12 inches. Beginning April 27, all baits are allowed and anglers may keep up to five trout over 8 inches but only three over 15 inches.

Spring Mill Pond at Island Lake Recreation Area is closed to fishing March 15- 31. From April 1-25 anglers are limited to artificial lures only, catch-and-release fishing. This year the lengthy winter may keep ice on the pond longer than normal and prevent fishing in early April. Youth under the age of 12 may keep one fish between 8 and 12 inches. Beginning April 26, all baits are allowed and anglers may keep up to five fish over 8 inches but only three over 15 inches.

The Clinton River upstream of Dequindre Road is not classified as a trout stream, so trout fishing is open year-round with an 8-inch minimum size limit and a five-fish daily possession limit, of which no more than three may be 15 inches or longer.

See the 2014 Michigan Fishing Guide for complete regulation details. For more information about this stocking effort, please contact the DNR offices at Proud Lake (248-685-2433), Island Lake (810-229-7067) or the Waterford Fisheries Office (248-666-7445).

DNR adds 2 miles metro trout fishing opportunities along Vermillion

Metro anglers who want to stick close to home for the April 12 stream trout opener will have nearly two additional miles of shoreline to explore as a result of acquisitions made by the Minnesota Department of Natural Resources in Dakota County.

Half a mile north of Dakota County Road 66 along County 79, the DNR has acquired a 52-acre aquatic management area that straddles the main branch of the Vermillion River, protecting 4,100 feet of shoreline. Upland areas of the property include five acres of grasslands and 25 acres of woods.

Further east, a 62-acre acquisition now affords access to the south branch of the Vermillion River just south of County Road 66 and west of state Highway 52. That parcel includes 6,900 feet of shoreline, 25 acres of grassland and 20 acres of woodland. The south branch is a coldwater tributary to the Vermillion that provides rearing areas and offers refuge for trout, especially during hot summer weather.

Both properties provide habitat for pheasants, turkeys, ducks, doves, deer and other wildlife; they also will be open to hunting, trapping and wildlife watching. The DNR’s Fisheries section will continue to work with the DNR Wildlife section to manage upland areas. 

“These properties are a great addition to the region’s outdoor recreation system, especially for busy metro anglers and hunters who may not always have time for a several-hour drive,” said T.J. DeBates, DNR’s east metro fisheries supervisor. “Acquisitions like these not only protect habitat, they also provide much needed public access.”

The two properties cost $384,200. Funding was provided by the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources. Money for the properties also came from the Outdoor Heritage Fund, created after voters approved the Clean Water, Land and Legacy Amendment in November 2008, which increased sales tax by three-eighths of 1 percent. The fund receives one-third of the sales tax dollars and may only be spent to restore, protect and enhance wetlands, prairies, forest and habitat for game fish and wildlife. Dakota County also contributed to the acquisitions.

The Vermillion River has gained notoriety over the past 10 years as a trophy brown trout stream within 45 minutes of a major urban area. As recently as 1960, though, the stream was considered unfit for any game fish due to poor water quality from industrial wastes and land use practices. The river’s comeback has been the result of local, regional and state efforts to improve water quality.

Since 2005, the DNR has acquired land protecting nearly 10 miles of shoreline along the Vermillion for habitat and public access for fishing and hunting. The DNR also has worked with local government and nonprofit conservation organizations on several stream restoration projects along the Vermillion.

DNR seeks feedback on expanding trout seasons - Asks anglers to weigh in at Spring Fish & Wildlife Hearings

MADISON - Moving the start of the early trout season to January 1 and expanding the early season to all inland waters to provide more fishing opportunities are among the options Wisconsin anglers can weigh in on during the 2014 Spring Fish and Wildlife Hearings held April 14 at sites in all Wisconsin counties.

This hardy angler braved harsh weather to enjoy opening weekend of the 2014 early catch and release season --and was rewarded for his efforts. WDNR Photo

The six advisory questions on trout topics, Spring hearings questionnaire questions 22-27 [PDF], are the latest step in a comprehensive review of trout fishing in Wisconsin launched in 2011. The questions are designed to help gauge support for possible season changes, one of many components under consideration as the Department of Natural Resources develops a rule package aimed at improving anglers' trout fishing experiences without jeopardizing the quality of the fishery.

"We are trying to provide more fishing opportunity for trout anglers," says Scot Stewart, the DNR fish supervisor leading the review effort. "At the same time we are trying to respect regional desires throughout the state. We are using the advisory questions to focus in on those desires."

Anglers also will get a chance to share their input during public informational meetings planned for summer 2014. Both will be used to shape a proposed trout regulation rule package for consideration at the 2015 Spring Fish & Wildlife Rule Hearings, Stewart says.

These public input opportunities are part of the statewide effort launched in 2011 to review inland trout fishing because it had been more than 25 years since DNR had collected angler input on a statewide basis, says Joanna Griffin, a fisheries specialist who leads DNR's trout team. Trout populations, trout streams, and trout angler habits and attitudes themselves had changed significantly over that time. Trout populations, for instance, increased overall on a statewide basis as has the number and mileage of trout streams, a story told in "A Trout Treasury" in the April 2011 Wisconsin Natural Resources magazine.

To get that initial input, DNR held public meetings in March 2011, conducted an online survey, and followed with a mail survey of former anglers to understand why they left the sport Results of the 2011 Survey of Lapsed Wisconsin Inland Trout Anglers [PDF, 341KB] .

Results from a mail survey of current inland trout anglers sent in February 2012 is now being finalized. That survey was sent to 1,000 randomly-selected purchasers of the 2011 inland trout stamp. In early 2013, DNR formed a Trout Management Task Force to review the survey results, provide input, and develop goals for the future of Wisconsin's trout fisheries. The group included 40 people from around Wisconsin who represent the Conservation Congress, conservation organizations, and businesses and fishing guides with an interest in trout fishing.

Based on the task force's input, DNR's trout team put together the advisory questions related to season changes, says Griffin.

The advisory questions, in addition to moving up the opening day of the early trout season, ask whether the season should be statewide. Right now, much of northeastern Wisconsin and selected waters elsewhere are closed during the early season. Other questions ask whether the early season should end the day before the regular season begins, eliminating the five-day closure now in place between the two seasons.

Anglers are also asked if they want to extend the regular season to Oct. 15 from Sept. 31, as it is now, with options of making the extra two weeks open to harvest or to catch and release only, Griffin says.

Finally, anglers are asked if they favor a uniform gamefish season for so-called put-and-take trout lakes and ponds, where catchable size fish are stocked every spring but where the lakes and ponds may not support survival over winter.

March 13 online chat set on trout advisory questions

Anglers and others with question about the trout advisory questions or the surveys are invited to join DNR for an online chat at noon March 13. People who can't join at that time can read the transcript later at their convenience.

Griffin, Stewart, Matt Mitro, DNR trout researcher, and Marty Engel, longtime fish manager for Pierce, Dunn and St. Croix counties, and Jordan Petchenik, the DNR research scientist who conducted the surveys, will participate in the online chat.

To participate, visit dnr.wi.gov, and look for the box on the right to enter the chat, or search the phrase "ask the experts." Or join the conversation on the DNR Facebook page, www.facebook.com/WIDNR, by clicking the "Cover it Live Chat" box on the top of the page. The transcript will be available after the chat at that same link.

Griffin named statewide trout coordinator

Joanna Griffin, a fisheries specialist for DNR since 2000, is taking over as statewide trout coordinator for the fisheries program, a role vacant since the 2011 retirement of Larry Claggett.

Joanna Griffin takes over as leader of DNR's trout team. WDNR Photo

"Joanna Griffin has been accomplishing great things for the trout program: organizing and writing the Trout Stamp Reports, coordinating the report database for trout habitat projects, and serving as the liaison to the trout team," says Steve Hewett, fisheries management section chief. "We look forward to her leadership and coordination skills to help us forge ahead with our trout review and continue to provide some of the best trout fishing in the country."

Griffin, who grew up in southern Vermont, graduated from Vassar College and completed her graduate studies in Woods Hole, Mass., through the Boston University Marine Program. She worked for two years at Marine Research, Inc., an environmental consulting firm in Falmouth, Mass., before joining DNR in 2000 as the assistant propagation coordinator.

Since 2001, Griffin has had multiple project positions with DNR fisheries management and the University of Wisconsin-Stevens Point. In 2011, she became a staff specialist working on a panfish management plan, trout habitat reporting and trout stream classification. Griffin lives in Madison with her husband and two children, all accomplished anglers.