Friday, May 2, 2008

Meet the bull trout

Express Staff Writer

Bull trout (Salvelinus confluentus) are found in cold streams and rivers throughout the Pacific Northwest—in Idaho, Montana, Washington, Oregon and Nevada as well as in western Canada. Bull trout have more specific habitat requirements compared to other salmonids. Those needs appear to influence their distribution and abundance, according to information provided by the U.S. Fish and Wildlife Service.

According to the federal agency, bull trout are primarily threatened by poor water quality, habitat degradation, loss of traditional migratory corridors due to dams and stream dewatering, and past fisheries management actions that introduced non-native, competing fish species such as brown, lake and brook trout. The fish need cold water to survive, so they are seldom found in waters where temperatures exceed 59-64 degrees Fahrenheit.

Bull trout exhibit two forms: resident and migratory. Resident bull trout spend their entire lives in the same stream or creek. Migratory bull trout move to larger bodies of water to rear young and then migrate back to smaller waters to reproduce.

An anadromous form of bull trout also exists in Washington's coastal Puget Sound population, which spawns in rivers and streams but rears young in the ocean. Resident and juvenile bull trout prey on invertebrates and small fish. Adult migratory bull trout primarily eat fish and may grow as long as 35 inches and weigh 32 pounds.

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