Failure of Submersed Macrophytes to Provide Cover for Rainbow Trout throughout Their First Winter in the Henrys Fork of the Snake River, Idaho

Autor: J. S. Griffith, R. W. Smith
Rok vydání: 1995
Předmět:
Zdroj: North American Journal of Fisheries Management. 15:42-48
ISSN: 1548-8675
0275-5947
DOI: 10.1577/1548-8675(1995)015<0042:fosmtp>2.3.co;2
Popis: Submersed aquatic plants that are abundant in some stream reaches have a potential to provide winter concealment cover for juvenile salmonids. We monitored an index of macrophyte abundance in a portion of the Henrys Fork of the Snake River during two winters that differed in severity and assessed the densities of age-0 rainbow trout Oncorhynchus mykiss associated with the macrophytes. The macrophyte index averaged 84–87%, in November 1989 and 1992, and an average of 10–13 fish/100 m2 were concealed there. In 1990, macrophyte cover declined to 59% in January and 46% in early February; fish density declined by about one-third by January and dropped to nearly zero in February. In 1992–1993, the macrophyte index declined to an average of 39% following anchor ice formation in December and to 32% in January. Fish density in December was reduced to about half of the November density and to about 1 fish/100 m2 in January. Movement of marked fish in 1989–1990 was predominantly from macrophytes into cobble...
Databáze: OpenAIRE
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