Media Tip Sheet
Midwest Region

Isle Royale National Park: Coaster Brook Trout

Isle Royale National Park is undergoing a comprehensive review of research activities on the island including the historic wolf-moose studies led by Michigan Tech. researchers and coaster brook trout work led by the U.S. Fish and Wildlife Service. Nine highly acclaimed academics from Alaska to North Carolina and points in between have been contracted to provide review of existing activities and recommendations for future research at the island.

Isle Royale National Park is one of the most remote and unique wilderness areas in the U.S. The park consists of one large island surrounded by about 400 smaller islands; it includes submerged land which extends 4.5 miles out into the largest freshwater lake in the world. Due to Isle Royale's biological and ecological uniqueness, it was designated an International Biosphere Reserve in 1980.

Isle Royale is home to three of about a dozen populations of coaster brook trout remaining in Lake Superior. Data collected by the Service such as age and size at maturity has contributed to management actions by the Park and Michigan DNR to help ensure the continued existence of coasters at Isle Royale.

Histroy of Coast Brook Trout

Coasters are brook trout that live at least some of their life in the Great Lakes or in the ocean along the Atlantic coast of North America. In Lake Superior they usually swim up tributary streams to spawn in late fall, but may also spawn along the lake shore. Adult coasters will return to their birth streams when they are mature, usually in about 3-5 years.

Coasters differ from other types or "strains" of brook trout generally by the habitats they live in and the great size that they attain (mature adults are usually over 12 inches long and may weigh several pounds) and color (more silvery), and have longer life spans. Record trout of over 10 pounds (4.5 kg) have been documented in some populations, but the average fish encountered range from 1 to 4 pounds (.5-2 kg) in weight. Named after their fondness for Lake Superior's rocky shore lines, coasters were the darlings of 19th century anglers from America and Europe. Diaries from the period joyfully record the fish's brilliant colors, trophy size, gourmet taste and eagerness to rise to the bait.

Sadly, predictions in the late 1800s that this bonanza couldn't last, came true. The unregulated coaster brook trout fishery was easily overfished and human activity damaged watersheds. For example, spawning beds were buried under sand churned up as rafts of freshly cut timber headed downstream to sawmills. Trout population numbers began a downward spiral. By the 1940s, the number of wild coaster populations was reduced to a mere half-dozen. See more (PDF).


Last updated: April 4, 2013