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Effects of Steelhead Density on Growth of Coho Salmon in a Small Coastal California Stream
Author(s) -
Harvey Bret C.,
Nakamoto Rodney J.
Publication year - 1996
Publication title -
transactions of the american fisheries society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.696
H-Index - 86
eISSN - 1548-8659
pISSN - 0002-8487
DOI - 10.1577/1548-8659(1996)125<0237:eosdog>2.3.co;2
Subject(s) - fish measurement , rainbow trout , oncorhynchus , fishery , juvenile , fish migration , riffle , fish <actinopterygii> , zoology , biology , environmental science , ecology , habitat
Weight change in age‐0 coho salmon Oncorhynchus kisutch at about natural density was negatively related to the density of juvenile steelhead (anadromous rainbow trout O. mykiss ) in a 6‐week experiment conducted in July–August 1993 in the north and south forks of Caspar Creek, California. The experiment used 12 enclosed stream sections, each containing a pool and a portion of upstream riffle, with two replicates of three steelhead densities—zero, natural density (1×), and twice the natural density (2×)—on both the north and south forks. The natural density of coho salmon was about one‐sixth the density of steelhead. Coho salmon survival was high (87% overall) and not related to treatments. In the north fork, coho salmon weight change was positive in zero density steelhead treatments, zero in 1× treatments, and negative in 2× treatments. Coho salmon weight change in the south fork was less favorable than in the north fork but was also negatively related to the density of steelhead. These results indicate that under some conditions resource partitioning by salmonid species does not eliminate negative interspecific interactions.