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Summer Food Limitation Reduces Brook and Rainbow Trout Biomass in a Southern Appalachian Stream
Author(s) -
Ensign William E.,
Strange Richard J.,
Moore Stephen E.
Publication year - 1990
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(1990)119<0894:sflrba>2.3.co;2
Subject(s) - salvelinus , rainbow trout , zoology , trout , biomass (ecology) , fontinalis , population , biology , fishery , body weight , dry weight , predation , ecology , fish <actinopterygii> , agronomy , demography , sociology , endocrinology
We assessed salmonid production in summer in a second‐ and third‐order montane stream in eastern Tennessee in 1987. We sampled three stream sections, one containing exclusively brook trout Salvelinus fontinalis , one containing exclusively rainbow trout Oncorhynchus mykiss , and a third with a mixture of both species. Population estimates for July and October 1987 revealed reductions in biomass over the 4‐month period that ranged from 31 to 49%, whereas population densities declined by 32–46% during the same period. Total net production during the 4‐month period was low and ranged from 0.38 to 0.45 g/m 2 . From June through September, the mean number of prey items per stomach ranged from 4.2 to 29.9, whereas the mean relative weight of stomach contents ranged from 0.12 to 1.34 mg dry weight per gram wet weight offish flesh. There was a strong positive correlation between the mean relative weight of stomach contents and the mean condition factor for a given date. Calculated energy intake was below the level necessary to provide energy for maintenance metabolism.