title: Use of streambed substrate as refuge by steelhead or rainbow trout Oncorhynchus mykiss during simulated freshets.
abstract: A flume was used to estimate the carrying capacity of streambed substrates for juvenile steelhead or rainbow trout Oncorhynchus mykiss seeking refuge from simulated freshets. The simulated freshets had mean water column velocities of c. 1·1 m s(-1). The number of O. mykiss finding cover within the interstices of the substrate was documented for different substrate sizes and levels of embeddedness. The availability of suitable refuges determined the carrying capacity of the substrate for O. mykiss. For the size of the O. mykiss tested [mean ± s.d. fork length (L(F)) = 122 ± 12.6 mm], the number of interstices with depths ≥200 mm measured with a 14.0 mm diameter flexible plastic tube was the best predictor of the number of O. mykiss able to find cover (r(2)  = 0.75). Oncorhynchus mykiss seeking refuge from freshets may need deeper interstices than those seeking concealment at autumn or winter base flows. The availability of interstices suitable as refuge from high flows may determine autumn and winter carrying capacity.
authors.affiliation: Stillwater Sciences, 850 G St, Ste K, Arcata, CA, 95521-6238, U.S.A.
authors.forename: F K
authors.initials: FK
authors.lastname: Ligon
authors.affiliation: USDA Forest Service, Pacific Southwest Research Station, 1700 Bayview Dr, Arcata, CA, 95521-6013, U.S.A.
authors.forename: R J
authors.initials: RJ
authors.lastname: Nakamoto
authors.affiliation: USDA Forest Service, Pacific Southwest Research Station, 1700 Bayview Dr, Arcata, CA, 95521-6013, U.S.A.
authors.forename: B C
authors.initials: BC
authors.lastname: Harvey
authors.affiliation: Stillwater Sciences, 2855 Telegraph Ave, Ste 400, Berkeley, CA, 94705-1128, U.S.A.
authors.forename: P F
authors.initials: PF
authors.lastname: Baker
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D017753:Ecosystem; D017686:Oncorhynchus mykiss; D000068236:Refugium; D045483:Rivers; D012621:Seasons; D014872:Water Movements
keywords: displacement; embeddedness; flood; high flows; interstitial; velocity