TRAVERSE CITY, Mich. (AP) -- Federal officials have decided against placing the coaster brook trout on the endangered species list, even though the fish has become increasingly rare after long flourishing in the upper Great Lakes.
The U.S. Fish and Wildlife Service on Monday said a yearlong review had concluded that coasters were not distinct enough from other brook trout to list them as endangered or establish protected habitat.
"Coasters" are born in rivers and streams, but migrate to lakes and spend most of their lives there, drifting along the coast. They tend to grow larger than other brook trout, which remain within their native streams. Many coasters are 1 to 2 feet long.
Their historical range took in parts of lakes Huron, Michigan and Superior. Roughly 119 Superior tributaries and a half-dozen streams flowing into Huron once supported coasters. But overfishing and habitat degradation in the 1800s nearly wiped them out.
Today, just 15 stream-spawning and three lake-spawning populations are known to exist -- all in Lake Superior.
The Sierra Club and the Huron Mountain Club, a private hunting and fishing preserve in Michigan's Upper Peninsula, petitioned the government in 2006 to designate the coaster as endangered.
Marvin Roberson, a Sierra Club policy specialist, said the group would consider its options, including a lawsuit in federal court to overturn the Fish and Wildlife Service's decision.
"We strongly disagree with it," Roberson said.
Peter Dykema, fisheries manager for Huron Mountain Club, said: "We believe that the surviving coaster population easily satisfies the statutory standards for listing. We are reviewing our legal options to seek review of the Service's decision."
Researchers are uncertain whether the coaster is a genetically separate species. Still, the conservation advocates contend its unique migratory behavior qualifies the fish for listing as a distinct segment of the brook trout population.
But the Fish and Wildlife Service said its review did not yield convincing evidence the coaster was a distinct population segment, much less a separate species or subspecies.
Instead, the agency labeled the coaster a "life history form" that could be reconstituted from other brook trout under the right environmental conditions.
"Thus, the population health of coasters is essentially equal to the population of brook trout in the upper Great Lakes," the agency said in a statement.
"Although coaster brook trout have declined and threats remain, there are at least 200 brook trout populations within the upper Great Lakes and the overall population numbers of brook trout within the upper Great Lakes remains high."
Roberson said the government acknowledged coasters differ from other brook trout in numerous ways, including size and behavior. "And then, incredibly, they say there's no genetic difference between them," he said.
Self-sustaining coaster populations are found in the Salmon Trout River in the Upper Peninsula, which flows through property owned by the Huron Mountain Club, and in the waters of Lake Superior's Isle Royale National Park.
Coasters also live in a few streams on the Canadian side of Superior and in Ontario's Lake Nipigon.
Government agencies, nonprofits and Indian tribes in the U.S. and Canada are trying to restore the colorful fish. Strict limits are imposed on catching them.
Other efforts include habitat improvements such as removing or redesigning dams that block stream access. Some sections of Lake Superior have been stocked with brook trout.
Logging and road construction can harm coasters by causing sediment to erode into spawning areas, Roberson said.
Opponents of a proposed nickel and copper mine in the Upper Peninsula say it also could pose a danger. The mine would extend beneath a section of the Salmon Trout River. Kennecott Eagle Minerals Co. says its project would not harm the fish.