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Annual Production, Production/Biomass Ratio, and the Ecotrophic Coefficient for Management of Trout in Streams
Author(s) -
Waters Thomas F.
Publication year - 1992
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(1992)012<0034:appbra>2.3.co;2
Subject(s) - rainbow trout , trout , salvelinus , salmo , brown trout , streams , fishery , fishing , fish migration , environmental science , zoology , fontinalis , biology , hectare , biomass (ecology) , ecology , fish <actinopterygii> , computer network , agriculture , computer science
This paper reviews the annual production, annual P / B ratio (annual production/ annual mean standing stock), and ecotrophic coefficient (annual angler harvest/annual production) of brook trout Salvelinus fontinalis , brown trout Salmo trutta , and rainbow trout Oncorhynchus mykiss in streams. Most estimates of annual production in fertile streams ranged from 100 to 300 kg/hectare. Annual P / B ratios varied with number of age‐groups in species populations. The annual P / B ratio was about 2.0 for anadromous rainbow trout populations with two or three age‐groups, about 1.5 for brook trout populations with four age‐groups, and about 1.0 for brown trout populations with five to eight age‐groups. The ecotrophic coefficient was about 0.25–0.50 for resident stream trout populations under normal regulations, but under special restrictive regulations, it dropped to about 0.10 or less. Poor access to the stream also lowered the coefficient, even under normal regulations, apparently by reducing harvest. Some extremely high coefficients (0.75–1.00) probably reflected excessive angling pressure, Species highly vulnerable to angling, such as the brook trout, had high ecotrophic coefficients–about 0.50–0.75. The greatest potential value of the ecotrophic coefficient may be to provide a simple quantitative assessment of how different management practices affect the proportion of energy removed by angling to energy fixed by production.