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Stratified Subsampling for Determining Age Distributions
Author(s) -
Ketchen K. S.
Publication year - 1950
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(1949)79[205:ssfdad]2.0.co;2
Subject(s) - sampling (signal processing) , fish <actinopterygii> , statistics , reliability (semiconductor) , age groups , distribution (mathematics) , fishery , composition (language) , stratified sampling , flounder , mathematics , environmental science , computer science , biology , demography , telecommunications , physics , mathematical analysis , power (physics) , quantum mechanics , detector , sociology , linguistics , philosophy
Effective age composition studies in large fisheries demand sampling of very large numbers of fish. Establishment of a practical program of investigation calls for measures which reduce the actual age determination to a point where it can be conveniently handled. A method is described whereby age composition is determined from a large number of length measurements using a relatively small number of age determinations. The procedure is an independent modification of one suggested by Fridriksson in 1934 and is an improvement in that it gives more accurate results for those age groups at the extremities of the distribution. Samples of a Pacific coast flounder have been drawn upon to demonstrate the reliability of the method for various types of size distribution and for various levels in the intensity of age sampling.