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Critical notes on a proposed method to estimate production
Author(s) -
ZWICK PETER
Publication year - 1975
Publication title -
freshwater biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.297
H-Index - 156
eISSN - 1365-2427
pISSN - 0046-5070
DOI - 10.1111/j.1365-2427.1975.tb00121.x
Subject(s) - production (economics) , population , sample (material) , mathematics , statistics , ecology , thermodynamics , economics , biology , physics , demography , microeconomics , sociology
Summary To estimate annual production, Hamilton (1969) initially calculated mean losses/sample, as did Hynes (1961) and Hynes & Coleman (1968). While the latter failed to convert these means to annual production, Hamilton has overcome this problem by assuming a population at equilibrium. Then, production may be calculated by multiplying mean losses with the number of classes through which specimens can grow. The method was claimed to be suitable for unidentified material and not to depend strongly on growth patterns; both claims are refuted here. The main objection is that for calculations, populations must be divided into fractions. While equilibrium might be acceptable for an entire population, it is not for any of its fractions. The particular conversion factor therefore has no justification and the method becomes inapplicable.