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| Coaster brook trout |
People like you and me. Organizations and governments. Community and conservation groups. Private citizens and generous corporate sponsors - all pitch in to help the Ministry of Natural Resources protect and restore the biological diversity of the Great Lakes. It takes all of us working in close partnerships to make this happen under the umbrella of the Canada-Ontario Agreement Respecting the Great Lakes Basin Ecosystem (COA).
What are coaster brook trout?
Fisheries biologists have long wondered why some of Lake Superior’s brook trout live out their days in the oxygen-rich cold waters of the rivers and creeks where they were spawned and hatched while still others migrate from their home rivers and streams when they are quite young. These latter ones seem to seek Lake Superior’s open waters to grow and mature. This migratory behaviour has given rise to the name “coasters” – since these brook trout travel out to and wander along the coastal waters of Lake Superior.
Coaster brook trout are found only in Lake Superior and its tributaries, and also in Lake Nipigon. They mature later, live longer and grow larger than brook trout that stay in streams and rivers. Historically, coasters were found in Lakes Huron, Michigan and Superior and in more than 50 streams along Lake Superior’s shores as well as those of Michigan, Wisconsin and Minnesota.
These fascinating fish were once found across the Ontario basin of Lake Superior but now can only be found in large numbers in the lake’s western waters – in the Nipigon Bay area. The species has since become locally extinct (extirpated) in Lakes Huron and Michigan.
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| Coaster brook trout in net |
Why are coaster brook trout numbers in decline?
Fisheries biologists think that the combination of logging, road and railway construction at the beginning of the 20th century were contributing factors to the coasters’ decline.
Later on, fluctuating water levels from hydro dams and shoreline development, they believe, altered the coaster’s native stream habitat and hindered its spawning migrations. It is also possible that competition for food and a healthy natural habitat from non-native fish such as rainbow trout, over-harvesting by sport anglers, accidental commercial harvesting, and predation by invasive sea lamprey took their toll.
Since little is known about the reasons for the coasters’ unusual habit of migrating between stream and lake, the definitive cause or causes of their decline is still a mystery.
How do partners help restore these fish … and what’s being done?
Many people are interested in these unusual fish and so a number of projects are underway to study the coaster brook trout and learn more about them. Many of the projects have several partners and all have three key objectives:
• to understand what triggers a brook trout to leave its home waters and become a coaster
• to determine which streams in the Lake Superior basin are “home” to coasters
• to measure any successful habitat restoration within those streams.
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| Marilee Chase |
MNR’s Marilee Chase, COA Lake Superior Basin Coordinator out of Thunder Bay leads the team of MNR staff and its many partners who are helping to unravel the “migration mystery.”
She says, “We’re trying to determine at what stage the trout leave the streams and rivers. We also want to know which environmental triggers might cause this behaviour. We’re working in Nipigon Bay because a large number of brook trout move in and out of its feeder streams.
We tag some of the fish and then use transponders and computerized stream readers which automatically monitor their movements so we can figure out when the coasters come and go and under what conditions they migrate.”
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| Steve Chong holding a "coaster" |
Biologists Steve Chong and Sue Greenwood work with partners in the Sault Ste. Marie area where they monitor restoration of coaster spawning habitat in eastern Lake Superior. They have learned that habitat rehabilitation is important for restoration of the species. Restocking, when necessary, is also used to supplement coaster brook trout numbers.
Steve says, “We’re collecting tissue samples from brook trout populations living in the eastern basin of Lake Superior to determine their genetic relationship to other wild and stocked brook trout found in Lake Superior. This work will allow us to compare streams where coaster brook trout exist, with streams where they’re absent to determine what conditions, if any, might hinder our efforts to help restore them.”
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| Sue Greenwood |
“We’re looking along hundreds of kilometres of shoreline to find coaster populations,” explains Sue. “By examining tissue and scale samples, we can detect any genetic relationships between existing fish and those that were stocked in the ‘80s.”
“This kind of information will help reestablish coasters in this area,” notes Steve.
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| Measuring a Coaster brook trout |
MNR research scientist for Northern Forest Ecosystems, Dr. Rob Mackereth, monitors the effects of forest management on the headwaters of coaster brook trout rivers. MNR staff and their partners are checking 20 target streams - measuring geology, topography and forest cover - to see if changes in water temperature and flow resulting from forestry activities have a harmful effect on the coasters’ spawning and rearing habitat. They expect to be able to create some best practices to minimize any negative effect forestry activities might have on spawning habitat.
Rob says “Coasters are symbols of the strong connection between terrestrial and aquatic ecosystems. Because their life cycle involves both open lake and stream habitats, maintaining the health of both systems helps not only the coaster but other species as well.”
The mystery continues to puzzle people, but with everyone’s help, these fish will survive and multiply continuing to add to our natural biodiversity.
Key partners, stakeholders and supporters
• Fisheries and Oceans Canada
• The Thunder Bay Fly Fishers
• The North Shore Steelhead’ Association
• Ontario Federation of Anglers and Hunters
• Parks Canada
• The Sault Fly Anglers Association
• Domtar
• The Great Lakes Fishery Commission
• Ontario’s Centre for Northern Forest Ecosystem Research (CNFER)
• The University of Guelph
• Many private land owners
