Pygmy Whitefish

Video of a school of several hundred pygmy whitefish preparing to spawn in the Cedar River above Chester Morse Lake. Females broadcast their eggs over the stream bed gravel and the eggs are then fertilized by the male fish.

The Chester Morse Lake population of pygmy whitefish (Prosopium coulteri) is one of nine populations currently found in lakes within the state of Washington. The species is known to have occurred historically in only six other lakes in the state.

Pygmy whitefish are not currently listed under the federal Endangered Species Act, but the species is listed as state sensitive by the Washington Department of Fish and Wildlife (WDFW). The population in Chester Morse Lake is considered to be a “strong-hold” in Washington state according to WDFW, as the fish live in a protected reservoir and are not subject to adverse impacts from development or subject to disturbance from fishing or recreation. Read more on the biology of pygmy whitefish on the Seattle Public Utilities Cedar River Biodiversity website.

Research on pygmy whitefish in Chester Morse Lake indicates that it is a primary food source for bull trout at some times of the year and spends most of its time near the lake bottom, rising toward the surface at night to feed. It spawns in lower reaches of the Cedar and Rex rivers during early December. Our understanding of how this species has been affected by past land use practices and reservoir operations is not extensive. Current research is directed at developing greater knowledge of the ecology of this species in Chester Morse Lake and how it may be impacted by current and future management of water levels.


Our long term goal for pygmy whitefish is to protect, maintain, and/or improve existing habitat needed during each pygmy whitefish life stage including spawning habitat, rearing habitat, and adequate conditions for the species in the reservoir system.

Our specific objectives include:

  1. Protect and maintain all aquatic and riparian habitats within the potential distribution of pygmy whitefish.
  2. Protect pygmy whitefish from human disturbance and fishing by maintaining a closed watershed.
  3. Restore stream and riparian habitat and and more natural hydrologic processes throughout the basin.
  4. Reduce sediment delivery to streams by decommissioning roads to improve spawning and rearing conditions for pygmy whitefish.
  5. Provide scientifically sound information about pygmy whitefish ecology to inform management decisions concerning reservoir operations.


What are we doing?


See slideshow of research on pygmy whitefish.

Strategic Planning
The Cedar River above Chester Morse Lake is a focus for a variety of restoration projects aimed at restoring hydrologic processes, improving water quality, and improving stream habitat, all of which contribute to better rearing and spawning conditions for pygmy whitefish.
View more about our strategic planning.

Protect All Watershed Habitats
Management of the watershed is intended to avoid and/or minimize adverse effects of major events and activities that could harm the pygmy whitefish population or its habitat, such as wildland fire, spills of toxic materials, invasive species, and excessive human disturbance.
View more information on habitat protection.

Aquatic and Riparian Habitat Restoration
Aquatic restoration projects are designed to improve stream and riparian habitat by increasing habitat complexity and restoring natural processes. Many of these projects should benefit pygmy whitefish spawning habitat.
View more information on our aquatic and riparian habitat restoration program.

Road Improvements and Decommissioning
Roads contributing sediment or blocking fish passage are decommissioned or improved to restore passage, create better habitat for all fish species and improve water quality. These improvements may benefit pygmy whitefish spawning habitat.
See more information on road improvements and decommissioning.

Aquatic Habitat Research and Monitoring
We conduct research aimed at better understanding habitat needs and general ecological characteristics of pygmy whitefish. Such studies contribute needed information for designing and evaluating habitat restoration and making more informed decisions concerning water supply operations.
See more on our aquatic and riparian research and monitoring program.