New Study Finds Decline in Brook Trout Due to Temperature and Land Cover Changes in Maryland
Report by DNR Biologist Published in North American Journal of Fisheries Management

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Annapolis, Md. — A new study by Maryland Department of Natural Resources biologists highlights the detrimental impact of development, loss of forest, and temperature changes on brook trout, Maryland’s only native trout species, in six Baltimore area streams.

“Over the last 30 years brook trout numbers have declined drastically in many Maryland streams and disappeared completely from several streams in the rapidly developing Baltimore metropolitan area,” said the study’s lead author Scott Stranko, a biologist with DNR’s Resource Assessment Service. “Brook trout are very sensitive to landscape alterations and stream temperature increases.”

The study analyzed brook trout distribution and abundance data collect by the DNR’s Fisheries Service over the last 3 decades against stream temperatures and land cover in Baisman, Goodwin, Timber and Red Runs, Sawmill Branch and Stillwater Creek. For every one percent increase in impervious land cover (parking lots, roadways, rooftops, etc.) in a stream’s watershed, the odds of brook trout survival decreased by nearly 60 percent.

In addition to warming temperatures due to climate change, forest clearing and development also often increase stream water temperatures which negatively affect brook trout, a cold water fish. The brook trout living in Maryland are near the southeastern edge of the species’ native habitat range and only occupy streams with summer water temperatures that stay below 75 degrees Fahrenheit.

Maryland’s population is expected to expand to more than 6 million people over the next decade, nearly doubled from 1970 levels.

“Our population growth and land use decisions have and continue to drastically alter the natural landscape and severely threaten many stream animals, especially Maryland’s remaining brook trout populations,” added Stranko.

The full study recently published in the North American Journal of Fisheries Management is available online.

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October 3, 2008

Contact: Olivia Campbell 410-260-8016 office I 410-507-7525 cell ocampbell@dnr.state.md.us

Maryland Department of Natural Resources (DNR) is the state agency responsible for providing natural and living resource-related services to citizens and visitors. DNR manages more than 449,000 acres of public lands and 17,000 miles of waterways, along with Maryland's forests, fisheries and wildlife for maximum environmental, economic and quality of life benefits. A national leader in land conservation, DNR-managed parks and natural, historic and cultural resources attract 12 million visitors annually. DNR is the lead agency in Maryland's effort to restore the Chesapeake Bay, the state's number one environmental priority. Learn more at www.dnr.maryland.gov.