Selecting trout habitat suitability criteria for instream flow studies
- Pacific Gas and Electric Co., San Ramon, CA (United States)
- EA Engineering, Science, and Technology, Lafayette, CA (United States)
Habitat suitability criteria (HSC) are a major component of the Instream Flow Incremental Methodology (IFIM) developed by the U.S. Fish and Wildlife Service (USFWS) to estimate the relationship between streamflow and fish habitat. Studies using the IFIM are used to allocate and manage water resources at hydroelectric projects and other streamflow regulating facilities. HSC are developed by observing fish in the wild, usually by snorkeling, and then performing a frequency analysis of the microhabitat features, such as the depth and velocity that the fish were seen using. The resulting HSC are specific to the particular stream reach at the time of observation. To aid selection of HSC for sites where HSC cannot be developed because of an insufficient number of fish to observe, poor visibility, or inaccessible study sites, we investigated the literature to find factors that affect HSC for rainbow trout (Oncorhynchus mykiss) and brown trout (Salmo trutta). Key factors found to significantly affect trout HSC included fish size, season, stream structure, competition, and food availability. The primary determinant in microhabitat selection and the resulting HSC was trout size. Generally, as their size increases, trout occupy swifter, deeper water. The literature review showed that transferring HSC from one stream PHABSIM site to another is valid only if the trout size distribution, species composition, stream structure, season when HSC data were collected, and other variables such as water temperature and food availability are sufficiently similar between the sites. The results of this study imply that HSC developed from data collected at numerous sites, where these factors varied widely or are unknown, cannot be assumed to apply to a particular study site. It is more appropriate to select HSC from a single stream site that is most similar to the new PHABSIM site in its physical and biological factors.
- OSTI ID:
- 219932
- Report Number(s):
- CONF-9507190-; TRN: 96:000708-0014
- Resource Relation:
- Conference: Waterpower 1995: international conference, San Francisco, CA (United States), 25-28 Jul 1995; Other Information: PBD: 1995; Related Information: Is Part Of Waterpower`95. Volume 1-3; Cassidy, J.L. [ed.]; PB: 2869 p.
- Country of Publication:
- United States
- Language:
- English
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