Threatened and Endangered Species - Status Reports
Date Published: September 1998
Number of Pages: 27
Pygmy whitefish (Prosopium coulteri) are remnants from the last ice age. In North America they are distributed across the northern tier of the United States, throughout western Canada and north into southeast Alaska. Pygmy whitefish are also found in one lake in Russia. Washington State is at the extreme southern edge of their native range in North America.
Pygmy whitefish are most commonly found in cool lakes and streams of mountainous regions. Streams they inhabit are of moderate to swift current, and may be silty or clear. In lakes, pygmy whitefish are frequently found in deep unproductive waters. However, they have been collected from smaller, shallow, more productive lakes in British Columbia and Washington. Washington lakes containing pygmy whitefish are typically unproductive. Pygmy whitefish have been caught in water depths ranging from 7 to 92 m in Washington.
Depending upon availability, food items consumed by pygmy whitefish include crustaceans, aquatic insect larvae and pupae, fish eggs and small molluscs.
Pygmy whitefish spawn in streams or lakes from late summer to early winter, depending upon geographic location and elevation. They probably scatter their eggs over coarse gravel, as do other species in this genus. Presumed spawning runs have been noted in several streams. Lake spawning by pygmy whitefish may have been observed in Priest Lake, Idaho in late October. Although lake spawning had not previously been documented in Washington, the presence of pygmy whitefish in Bead Lake, which has no spawning streams, verifies its occurrence.
Pygmy whitefish presence in heavily sampled lakes has often gone undetected because of the fish's small size (usually under 20 cm) and tendency to inhabit the deeper portions of lakes. Only recently, when sampling techniques were modified to target pygmy whitefish, was the Washington Department of Fish and Wildlife able to pinpoint their distribution in Washington State.
Historically, pygmy whitefish resided in at least 15 lakes in Washington. Currently they inhabit only nine. We do not know the status of the populations in these lakes. Their demise in six lakes is attributed to piscicides, introduction of exotic fish species and/or declining water quality. Pygmy whitefish, particularly in smaller lakes, are vulnerable to exotic fish species introductions and declining water quality, both of which may constrict their habitat.
Because of the very limited range of the pygmy whitefish in Washington, we believe they are vulnerable and likely to become endangered or threatened in a significant portion of their remaining range without cooperative management. For these reasons, the Department recommends that pygmy whitefish be listed as a sensitive species in the state of Washington.
Hallock, M., and P.E. Mongillo. 1998. Washington State status report for the pygmy whitefish. Wash. Dept. Fish and Wildl., Olympia. 20 pp.
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