A Comparison of Two Stratification Schemes Used in Sampling Canadian Atlantic Cod, Gadus morhua

Clay , Douglas (1989) A Comparison of Two Stratification Schemes Used in Sampling Canadian Atlantic Cod, Gadus morhua. Marine Fisheries Review, 51(1), pp. 33-38.

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Official URL: http://spo.nmfs.noaa.gov/mfr511/mfr5118.pdf

Abstract

Sampling is a key element in the assessment of any fish stock. It is often one of the most expensive activities of the management process; thus, improved efficiency can result in significant cost savings. In most cases a two-phase sampling strategy is employed. Two commonly used versions of such stratified random schemes were simulated using a test population based on Atlantic cod, Gadus morhua. A 1 otolith per 1 cm length frequency currently used for many flatfish and some smaller gadoids and a 3 otolith per 3 cm length frequency currently used for many of the larger gadoids. No difference was detected in the age composition or mean length at age for either scheme; however, 10 percent fewer otoliths were collected in 1 for 1 sampling than 3 for 3. There was an improvement of between 30 and 60 percent in the coefficient of variation of the estimated catch numbers at age using the 1 for 1 compared with the 3 for 3 stratified sampling. For these reasons and other operational considerations, the 1 for 1 stratified random design of sampling appears to be superior.

Item Type: Article
Title: A Comparison of Two Stratification Schemes Used in Sampling Canadian Atlantic Cod, Gadus morhua
Personal Creator/Author:
CreatorsEmail
Clay , Douglas
Refereed: Yes
Journal or Publication Title: Marine Fisheries Review
Volume: 51
Number: 1
Page Range: pp. 33-38
Date: 1989
ISSN: 0090-1830
Issuing Agency: United States National Marine Fisheries Service
Subjects: Fisheries
Management
Item ID: 9953
Depositing User: Patti M. Marraro
Date Deposited: 22 Aug 2012 13:39
Last Modified: 22 Aug 2012 13:39
URI: http://aquaticcommons.org/id/eprint/9953

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