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ON ESTIMATING ANNUAL PRODUCTION
Author(s) -
Hamilton Andrew L.
Publication year - 1969
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1969.14.5.0771
Subject(s) - voltinism , statistics , mathematics , production (economics) , econometrics , ecology , biology , economics , macroeconomics , larva
The method of Hynes and Coleman is modified to make it more adaptable and more consistent with their underlying assumptions. If most organisms comprising a community are univoltine and have approximately the same maximum size, the average standing crop can be used to obtain a realistic estimate of annual production. The size frequency distribution can be regarded as a first estimate of an “average cohort” when the number of “average cohorts” equals the number of size classes through which the organisms grow. If growth, in terms of the size units used, is assumed to be linear, then numerical differences in adjacent size classes can be attributed to mortality. When all size classes are considered together, the effect of nonlinear growth on the estimate of annual production is not large. In contrast, a serious error is introduced if the organisms are not univoltine. When the growth pattern and generation time are known, it is relatively simple to modify the average size frequency distribution to improve the estimate of the “average cohort” and hence improve the estimate of annual production. A reply to the criticisms of Fager is included.