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Effects of Cobble–Boulder Substrate Configuration on Winter Residency of Juvenile Rainbow Trout
Author(s) -
Meyer Kevin A.,
Griffith J. S.
Publication year - 1997
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 - 10.1577/1548-8675(1997)017<0077:eocbsc>2.3.co;2
Subject(s) - cobble , rainbow trout , substrate (aquarium) , stocking , juvenile , fish <actinopterygii> , trout , zoology , environmental science , fishery , geology , biology , habitat , ecology
We assessed first winter habitat use by placing wild rainbow trout Oncorhynchus mykiss (52–155 mm total length) in wire‐mesh enclosures with different cover treatments and at varying fish densities. Cobble–boulders substrates (20–40 cm diameter) were arranged in four different configurations: (1) no cobble–boulders, (2) cobble–boulders present but not touching, (3) cobble–boulders touching in a single layer, and (4) cobble–boulders touching and stacked in two layers. As the configuration of rock substrate was changed to create more concealment cover, the number of fish remaining in the enclosures after 96 h increased significantly, even though the quantity of rock substrate did not change. The initial stocking density of fish had no overall significant effect on the number of fish remaining in enclosures after 96 h. However, analysis of each cover × density treatment showed that when the substrate arrangement created little concealment cover, the number of fish remaining in the enclosures did not increase with an increase in initial fish density, but when the substrate arrangement created relatively more concealment cover, more fish remained in the enclosures when the initial fish density was increased. In trials with rock cover present, fish emigrating from the enclosures were larger than those remaining in the enclosures. Our results demonstrate the importance of the configuration of cobble–boulders substrate in determining its suitability as winter cover for rainbow trout.