Groups Try to Revive Coaster Brook Trout
PICTURED ROCKS NATIONAL LAKESHORE, Mich. — Barely noticeable beneath a wooden foot bridge, the wire antenna stretched across the gurgling Mosquito River is on the lookout for one of the Great Lakes’ most mysterious fish: the coaster brook trout.
A century and a half ago, portions of the Lake Superior shoreline teemed with coasters – brook trout that, for reasons still unknown, migrate into the big lake instead of remaining in tributary streams with other members of their species.
But word of Superior’s bountiful trout fishery spread, eventually drawing hordes of anglers. People were particularly dazzled by the coasters’ large size, tasty flesh and distinctive orange-reddish or yellowish undersides.
By the turn of the century, overfishing and habitat degradation sent the coaster into a tailspin from which it has yet to recover. Today, only scattered pockets remain in Lake Superior. Occasional sightings are reported in northern sections of Lake Huron and Lake Michigan, although scientists say they’re unconfirmed.
But more than two dozen government agencies, conservation groups and Indian tribes in the United States and Canada are working to bring back the coaster brook trout.
The Mosquito River, which flows through the western end of Pictured Rocks National Lakeshore before emptying into the lake, is among a half-dozen spots in Michigan where restoration projects are under way. Another is the Salmon Trout River, the only place on the southern Superior shore where native coasters – as opposed to transplants – are known to live.
The quest is about more than giving people a prize fish to pursue. A coaster comeback would represent a victory for native species at a time of rising concern about exotics wreaking havoc on the Great Lakes.
“We’ve done everything under the sun to these fish, and it’s pure luck that we still have them. I feel a moral obligation to bring them back,” said Rob Swainson, area biologist with the Ontario Ministry of Natural Resources in Canada. He is trying to boost coaster numbers where they are most abundant: the Nipigon River watershed and bay at the northernmost tip of Lake Superior.
The Great Lakes Fishery Commission approved a coaster rehabilitation strategy in 1999, a couple of years after federal and state agencies began placing young brook trout in the Mosquito River.
Scientists at Northern Michigan University are monitoring their movements. They’ve implanted tiny tags into more than 1,500 trout, each with a separate identity code.
When a fish swims beneath the antenna, its number is recorded by a computer system housed in a wooden box nearby. Brook trout that become coasters migrate to the big lake and spend most of their lives there, although they might return upstream to spawn.
“We’re trying to figure out what’s working and what isn’t as far as restoration goes,” said biologist Jill Leonard, the project coordinator. “We’re also interested in what kind of habitat is best, what kind of stream generates coasters and what kind doesn’t. We’re looking at environmental variables – temperature, rainfall, any conditions that might affect migration.”
Even as they work to restore the coaster, scientists are still puzzled over why these particular brook trout migrate to the lake.
They’re not a separate species, Leonard says – to the disappointment of some conservationists who would like them listed under the Endangered Species Act. But biologists are looking for genetic or physiological characteristics that set them apart.
Once in Lake Superior, they wander the rocky water bottoms near river mouths, feeding on smaller fish. Coasters live longer than ordinary brook trout and therefore grow larger, often exceeding 20 inches and weighing 2 to 3 pounds, although a few get considerably bigger. Three- to five-pounders are landed frequently in the Nipigon River area, Swainson said.
Lee Newman, a specialist with the U.S. Fish and Wildlife Service in Ashland, Wis., has studied the history of Great Lakes brook trout and concluded that stocking programs weren’t protecting them from capture before they could spawn. Another problem: Most hatchery fish weren’t from the region and were genetically unsuited to reproduce.
In the early 1990s, Newman teamed with the Grand Portage Band of Chippewa Indians in Minnesota, planting young brook trout of the Nipigon strain in two small streams. Within a few years, three- to four-pound coasters were returning to the streams.
Swainson, meanwhile, has been lobbying for coaster restoration on the Canadian side of the lake since arriving in Nipigon as area biologist in 1988. He has sought fishing limits and talked anglers into helping tag brook trout for growth rate studies.
Today, Canada prohibits keeping coasters smaller than 22 inches. In the United States, limits vary by state. Michigan this year imposed a 20-inch requirement, with possession of just one fish at a time allowed.
If Swainson had his way, coaster fishing would be entirely catch-and-release.
“Removing exploitation is the number-one thing,” he said. “But you’ve got to mix the politics and the biology and what’s socially acceptable.”
On the Net:
Trout Unlimited coaster page: http://www.tu.org/site/pp.asp?c7dJEKTNuFmG&b277893