The Distribution and Abundance of Great Basin Redband Trout: An Application of Variable Probability Sampling in a 1999 Status Review

Identification Information

Citation

Originator: Jeffrey M. Dambacher, Kim K. Jones, Hiram W. Li

Publish Date: 2001

Online Link: https://nrimp.dfw.state.or.us/crl/Reports/AI/Dambacher_et_al_Info_Report_2001-08.pdf

BPA Project #:

Contact Information

Agency: Oregon Department of Fish and Wildlife

Name: Kim Jones

Job Position: Project Leader

Telephone: (541)757-4263 x260

E-Mail Address: kim.jones@oregonstate.edu

Description

Abstract: Using a variable probability sampling design, streams throughout the entire range of Great Basin redband trout (Oncorhynchus mykiss ssp.) were randomly sampled use the EMAP sampling protocol, such that 35 sample sites were apportioned to each of six subbasins (Silver Lake, Lake Abert, Goose Lake, Warner Valley, Catlow Valley, and Malheur Lakes). A total of 185 sites (out of a target of 210) were visited by three-person crews that conducted habitat surveys and population estimates in sample reaches whose length were nearly 20 times their channel width. A minimal sampling intensity was based on previously encountered levels of between site variance in abundance estimates for the species. The population estimate for age 1+ redband trout was 948,852 fish (+/– 21%), with confidence limits ranging from 26% to 43% of individual subbasin estimates. Age 1+ fish abundance in terms of density (fish m-2) showed no significant differences between any subbasin, while there were significant differences in biomass (g m-2), where one subbasin had significantly higher (Catlow Valley) biomasses, and one significantly lower (Goose Lake). These comparisons were supported by like differences in mean weight (g fish-2). Analysis of stream habitat characteristics and fish abundance revealed no relationship, or model, that was generally consistent throughout the Great Basin, though interpretable patterns were evident within some stream systems where sampling intensity happened to be sufficiently high. Thus while a landscape level sampling design was well suited to address a regional estimate of abundance, useful interpretation of fish and habitat relationships appeared to be embedded within the stream level of organization, and could not be addressed by the variable probability sampling design set for a minimal sampling intensity.

Purpose:

Time Period of Content: 1999

Geographic Extent: Oregon - Silver Lake, Lake Abert, Goose Lake, Warner Valley, Catlow Valley, Malheur Lakes

Status: Final

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Format: PDF File

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