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Using Frequency Distributions of Catch per Unit Effort to Measure Fish‐Stock Abundance
Author(s) -
Bannerot Scott P.,
Austin C. Bruce
Publication year - 1983
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(1983)112<608:ufdocp>2.0.co;2
Subject(s) - negative binomial distribution , skewness , statistics , mathematics , frequency distribution , catch per unit effort , fishing , index of dispersion , population , index (typography) , fishery , demography , biology , poisson distribution , poisson regression , sociology , world wide web , computer science
Mean catch per unit effort often is used as an index of fish abundance, N. This index is often biased. Frequency distributions of catch per unit effort (C/f) and independent estimates of N from a headboat sport fishery for yellowtail snappers Ocyurus chrysurus off Islamorada, Florida, indicated that mean C/f underestimated changes in N. Frequency distributions of C/f were skewed and fit the negative binomial distribution. Some descriptors of the distributions (median, variance, negative binomial parameter k, and frequency of zero C/f) were systematically related to N. These relationships were used to derive an index of N less biased than mean C/f. The new index, square root of relative frequency of zero C/f, could be applicable to any recreational, scientific, or commercial fishing activity for which C/f distributions are available, skewed, and have fairly high frequencies of zero C/f. Skewness could be due to spatial dispersion of the fish population or to a gradient of skill among fishing units. Received September 28, 1982 Accepted June 3, 1983