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Sample Size Requirements for Detecting Changes in Some Fisheries Statistics from Small Trout Lakes
Author(s) -
Parkinson Eric A.,
Berkowitz Jonathan,
Bull Christopher J.
Publication year - 1988
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(1988)008<0181:ssrfdc>2.3.co;2
Subject(s) - trout , fishing , fishery , sample size determination , fish <actinopterygii> , catch per unit effort , sample (material) , statistics , electrofishing , environmental science , mathematics , biology , chemistry , chromatography
The purpose of this paper is to determine sample sizes needed to use t ‐tests to detect changes in indices of angling effort, catch per unit effort (CPUE), fish length, fish growth, and fish age. The results are presented in graphs of sample size versus detectable change for data from small trout lakes in southern British Columbia. Sample size requirements are most difficult to meet for indices of CPUE, effort, and age, but the cost of data acquisition appears reasonable even for small lakes with less than 1,000 angler‐days/year. Alternative choices for significance levels (0.01–0.20) and power (0.80–0.95) result in almost a six‐fold variation in sample size requirements.