Sampling The Commercial Catch And Use Of Calculated Lengths In Stock Composition Studies Of Pacific Halibut

Author : Heather L. Gilroy
Publisher :
ISBN 13 :
Total Pages : 48 pages
Book Rating : 4.3/5 ( download)

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Download or read book Changes in Commercial Catch Sampling and Age Determination Procedures for Pacific Halibut, 1982 to 1993 written by Heather L. Gilroy and published by . This book was released on 1995 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: The International Pacific Halibut Commission has sampled the commercial catch since the 1930s. Documentation for the years 1982 to 1993 of port coverage, logbook data collected, sampling methods, otolith sample size, the processing of otoliths in the lab, and otolith-related studies are presented in this report. Sampling ports were added as the pattern of landings shifted. Logbook data forms changed to reflect the use of more than one gear type per vessel and the use of non-halibut gear. Also initiated was the collection of information on gear lost or abandoned during the ever shortening openings. Length/age sampling within a port was changed from representing a port proportionally, to representing a vessel's hailed weight proportionally. This change was made in response to the shorter, higher volume unloading periods and was accomplished by changing from systematic sampling of slings (cargo nets) of fish to unbiased random sampling of fish. The total otolith sample size was reduced and sample sizes were set for each management area. Double blind aging was discontinued. Otolith studies relating to glycerin absorption, age validation using oxytetracycline, automated aging, and the use of otoliths to determine sex were undertaken.