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How many kinds of fish live in Maryland’s freshwater streams?
Which ones are most common, and which ones are rare?

Historically, about 100 kinds (or species) of freshwater fish were known to occur in Maryland.  The statewide Maryland Biological Stream Survey, conducted by the Department of Natural Resources (DNR) since 1994, has collected 85 species.  The five most abundant species are eastern blacknose dace, eastern mudminnow, Blue Ridge sculpin, bluntnose minnow, and creek chub.  Bluegill and pumpkinseed are the most widely distributed freshwater fishes.

Photo of bluntnose minnowcourtesy of Garold W. Sneegas, USGS, Non-Indigenous SpeciesResident stream species with total numbers less than 5,000 individuals are stonecat, ironcolor shiner, striped shiner, and logperch.  In addition to these uncommon species, mud sunfish, flier, glassy darter, stripeback darter, blackbanded sunfish, Maryland darter, and 22 other fish species are rare and classified by DNR as species of greatest conservation need.  The Maryland darter has not been seen since August 1988 and may be extinct in the State.  About 19 percent of Maryland’s stream miles have no fish at all. By contrast, a site in Double Pipe Creek in Carroll County, sampled by DNR in 2002, yielded a record high catch of 11,354 fish representing 26 species.  Nearly 70 percent of everything collected was one species, bluntnose minnow. 

The kinds and numbers of fish living in streams around the State can speak volumes about water and habitat quality.  In general, the highest quality streams have the most fish species, especially those species that are sensitive to water pollution.  

- Ronald J. Klauda, Ph.D.
Director, Monitoring and Non-Tidal Assessment Division
Resource Assessment Service
Maryland Department of Natural Resources

Photo of bluntnose minnowcourtesy of Garold W. Sneegas,
USGS, Non-Indigenous Species Fact Sheet

For more information:
Maryland Biological Stream Survey

USGS, Non-Indigenous Species Fact Sheet


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