The Legendary coaster brook trout: DNR works to rehabilitate the species

Written by David Green.

BY MICHIGAN DNR 

There is something to be said about very large brook trout. They are the stuff of legends, and none has gained so fair a reputation over the decades as what is commonly referred to as the coaster brook trout.

Although a coaster is indeed a brook trout, complete with all the flashy markings and sweet-tasting flesh, these remarkable fish live most of their lives in the very competitive environment of Lake Superior.dnr.trout_3

The nickname, coaster, came about because these fish spawn, as brook trout do, in rivers and streams, but then they go out into the big lake, where they live most of their lives roaming along the coastline of Lake Superior, foraging, hopefully avoiding piscivorous predators and growing large.

In fact, coaster brook trout commonly grow to more than 26 inches.

The Michigan Department of Natural Resources for many years has been cooperating with numerous other agencies in the Lake Superior Basin to rehabilitate what has become a dwindling coaster brook trout population. Stocking and inventory programs have been the common thread with Michigan, Wisconsin, Minnesota and Ontario, but recently Michigan enacted further angling restrictions, especially in the area around Isle Royale National Park, where it is believed that remnants of unique strains of coaster brook trout still live.


"In recent years, we have established new regulations that we hope will help the coasters build their populations again," said Steve Scott, DNR fisheries biologist in Newberry and Lake Superior Basin coordinator.

On Lake Superior, the minimum size limit for brook trout is 20 inches and the possession limit is one fish. Within four and one-half miles of Isle Royale National Park, catch-and-release fishing only is allowed and no fish can be kept.dnr.trout1

Before European settlement, these beautiful fish were abundant in Lake Superior's tributaries and coastal regions. Their decline echoed that of the native grayling, and for the last century they have been locally extirpated or are extremely rare. Biologists think that extensive logging during the late 19th century destroyed a good deal of coaster brook trout stream reproduction habitat with the infiltration of sand and other sediments. Over-fishing and the invasion of the sea lamprey in the 1950s also are factors believed to have played a role in collapsing the Lake Superior coaster brook trout fishery.

What remains in those clear, cold waters are remnants of the original coaster brook trout population, and biologist have identified strains within the small population pockets. Isle Royale is home to two distinct strains, the Tobin Harbor and Siskiwit. The DNR coordinates planting of Tobin Harbor and Siskiwit in Michigan. The Marquette State Fish Hatchery also raises a strain of coaster brook trout native to Canada, known as Nipigons. Over time, fisheries experts have come to believe they possess information that could drive the recovery of the species. Five streams in Michigan, for example, are the subjects of ongoing research and rehabilitation efforts. One stream, the Salmon Trout River in northern Marquette County, is thought to be the only location for natural reproduction of the coaster brook trout in Michigan.

"Fisheries managers from around the basin established a working group in 1997 and have been closely coordinating everyone's efforts ever since," Scott said.

Raised from wild stock in government-operated hatcheries, some young trout are fixed with a passive integrated transponder (PIT) tag, released when they reach four inches long and tracked to determine movement and mortality. The PIT tags have shown that coaster brook trout come and go from their home streams with frequency. The fish will move in and out of the home waters over the course of a few hours up to several days and more.

Scott emphasized the learning curve on this elusive species is gaining momentum but is far from complete.

The Michigan DNR committed to a five-year program, which is likely to be renewed when it expires at the end of this year. Results of these many years of study and effort are hard to detect, but that will not deter the rehabilitation program.

Scott added that, in fact, there may be some changes in the future of the program to add or change streams where the fish are planted, as well as introducing larger fish, which may allow for better survival to spawning age.

At Pictured Rocks National Lakeshore near Munising, more than 100,000 fingerling coaster brook trout have been stocked in Mosquito, Seven Mile and Hurricane rivers since 1999. At the end of this year, that stocking will be temporarily suspended. Following a few years of monitoring, the stocking process may be restarted if the stocking efforts are not showing evidence of success. Meanwhile, restoration efforts will be focused elsewhere.

"Patience is going to be a big key in the recovery of the coasters," said Scott.

• For more information on the coaster brook trout rehabilitation effort, contact Scott at (906) 293-5131.

    – June 27, 2007
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