Estimation Of Halibut Body Size From Otolith Size

Author : Joan E. Forsberg
Publisher :
ISBN 13 :
Total Pages : 57 pages
Book Rating : 4.:/5 (9 download)

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Download or read book Estimating Sex of Pacific Halibut (Hippoglossus Stenolepis) Using Fourier Shape Analysis of Otoliths written by Joan E. Forsberg and published by . This book was released on 1993 with total page 57 pages. Available in PDF, EPUB and Kindle. Book excerpt: [No. 29] At present, the sex ratio of the commercial halibut catch cannot be obtained easily, since the gonads are removed at sea. Halibut otoliths, which are collected by the International Pacific Halibut Commission (IPHC) for age determination, appear to have sex-related shape differences. A technique for sexing otoliths based on such shape differences would be a costefficient way to make this information available. In an attempt to quantify and analyze the apparent shape differences, Fourier shape descriptors are obtained from digitized otolith images. The descriptors, with and without otolith weight, are used to classify otoliths by sex. The data are divided into training and test sets of various sizes for classification analysis. Successful classification rates range between 71.4% and 73.6% for the test sets when otolith weight is included in the analysis. When the descriptors alone are used, successful classification rates are 63.9% to 65.3% for the test sets. Training set success rates are higher for males, a finding indicating somewhat higher variation in otolith shape among females. Given the results achieved in this study, otolith shape does not appear to be a reliable indicator of sex in Pacific halibut.