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Cramer Fish Sciences: UCM - Unit Characteristic Method   Innovative Scientific Solutions for Fisheries and Environmental Challenges  
Cramer Fish Sciences
"The special conference session on nutrient enrichment you arranged at the 2007 Oregon Chapter of the American Fisheries Society was most appreciated and well organized. Thanks again, and I'm looking forward to further collaboration with you and Cramer Fish Sciences."
Ken Ashley, Ph.D.
Limnologist and Senior Engineer
Greater Vancouver Regional District



UCM: Unit Characteristic Method

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Cramer Fish Sciences is proud to announce that the following reports, prepared by Steven P. Cramer and Nicklaus K. Ackerman, have been accepted for publication in "Pacific Salmon Environment and Life History Models: Advancing Science for Sustainable Salmon in the Future." Eric Knudsen, Hal Michael, Cleve Steward, editors. American Fisheries Society, Symposium 71, Bethesda, Maryland.







How do you determine the number of salmon, trout, or steelhead a stream can support? Cramer Fish Sciences uses an analytical tool developed by Steve Cramer called the Unit Characteristic Method, or UCM.

Using habitat measurements from standard stream surveys, the UCM utilizes quantitative methods to determine cause-and-effect relationships between habitat and fish production. It's all virtual so you can change various habitat parameters and see how fish populations are affected.

Stream habitat has delineable units — pools, riffles, or runs — which are the building blocks that determine fish densities. Different fish require different habitat, and the UCM can be used to analyze the habitat needs of steelhead trout, rainbow trout, spring and fall Chinook salmon, bull trout, and even cutthroat trout. By varying additional attributes of the stream, such as depth, cover, temperature, turbidity, and even nutrient loading, the UCM can effectively provide answers and guidance to those concerned with stream fish production.

 The UCM is especially valuable when comparing the benefit or impact to fish when stream features are altered or protected. Habitat factors that impact fish production can be identified. Some specific examples of how the UCM has helped PGE and Bonneville Power:

  • The Deschutes River Basin was analyzed to determine the number of steelhead that could be supported if passage above the dams was restored.
  • The Hood River Basin was analyzed to determine the number of wild steelhead and Chinook that hatchery supplementation should support.
  • The Yakima River Basin was analyzed to determine if irrigation drainage channels can support salmonids.

The UCM has also been considered for urban land-use planning to design land use regulations that would protect key fish habitat.

The UCM projects for PGE and Bonneville Power have utilized the following services:

  • Assembly of stream habitat data from standard surveys and water quality monitoring
  • Quantified relationships between salmonids and habitat features

The key outcomes of these projects has included:

  • Estimation of fish carrying capacity by stream reach
  • Distinction of stream suitability for different salmonids
  • Quantitative estimates of benefits or impacts from stream alteration

Cramer Fish Sciences continues to modify and improve the UCM. Currently, we are working with the Washington Department of Ecology to develop UCM as a tool for estimating changes in salmonid carrying capacity due to flow alterations.

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