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Test of Weighted Usable Area Estimates Derived from a PHABSIM Model for Instream Flow Studies on Trout Streams
Author(s) -
Conder Allen L.,
Annear Thomas C.
Publication year - 1987
Publication title -
north american journal of fisheries management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.587
H-Index - 72
eISSN - 1548-8675
pISSN - 0275-5947
DOI - 10.1577/1548-8659(1987)7<339:towuae>2.0.co;2
Subject(s) - trout , streams , salmo , hydrology (agriculture) , environmental science , standing crop , positive correlation , habitat , salvelinus , fontinalis , fishery , ecology , geology , fish <actinopterygii> , biology , geotechnical engineering , computer network , computer science , medicine , biomass (ecology)
An assessment was made of the biological validity of weighted usable area (WUA) from the physical habitat simulation (PHABSIM) model based on standing crops of trout (Salvelinus and Salmo spp.) measured in Wyoming streams and standing crops predicted by the habitat quality index (HQI). Tests were made in trout streams for (1) validity of the HQI, (2) relationships between WUA and measured standing crops in different streams, and (3) relationships between WUA and the HQI within streams. Significant correlation (r = 0.934; P <0.05) was found between HQI scores and trout standing crop during the low‐flow period. No significant correlation was found for WUA and the measured standing crop among different streams; correlation coefficients for all tests were either near zero or moderately negative. Significant positive correlations (P < 0.05) did exist for 7 of the 60 within‐stream analyses of WUA versus HQI; 19 other positive correlations were strong (r > 0.90), but statistical significance was limited by the number of data points at each site. Although positive correlations were expected for all 60 cases, 18 tests showed a negative correlation, 3 of which were significant. Analyses indicated that trout species, stream size, and stream gradient influence the validity of the within‐stream relationship between WUA and the trout standing crop predicted by the HQI. Among test streams with steeper gradients and where velocity exerted the greatest influence on the HQI score, a positive correlation was observed in all cases, regardless of stream size or dominant species. When an attribute other than velocity has the greatest influence on trout density with change in discharge, WUA estimates may be invalid. This observation indicates that a relationship between WUA and trout standing crop may exist, but the nature of the relationship is likely to be unique for each stream.