Effect of Allocation and Stratification Strategies on Precision of Survey Abundance Estimates for Atlantic Cod (Gadus morhua) on the Eastern Scotian Shelf

S. Gavaris and S. J. Smith

Department of Fisheries and Oceans, Biological Sciences Branch
Biological Station, St. Andrews, New Brunswick, Canada E0G 2X0

Source - Journal of Northwest Atlantic Fishery Science, Volume 7(2): 137-144
ISSN-0250-6408

 

Gavaris, S. and Smith, J. 1987. Effect of Allocation and Stratification Strategies on Precision of Survey Abundance Estimates for Atlantic Cod (Gadus morhua) on the Eastern Scotian Shelf. 7(2): 137-144. https://doi.org/10.2960/J.v7.a16

 

Abstract

One of the primary uses of bottom-trawl survey data, with respect to fisheries management, is the estimation of abundance of the species involved. Stratified-random estimates for Atlantic cod (ages 5-12) from these surveys was found to be inferior to what would have been obtained if simple random surveys had been conducted. These results were primarily due to suboptimal allocation of stations to strata. Historical data were used to devise alternative sampling strategies. This analysis indicated that the number of strata could be reduced considerably without loss of precision. An additional and important benefit of the smaller number of strata would be increased flexibility for allocation. With the present level of sampling, it would be necessary to reduce the number of strata to achieve proportional allocation of stations or to approximate optimal allocation.

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Language - English
Publisher - Northwest Atlantic Fisheries Organization (NAFO), Dartmouth, N.S., Canada
Publication Date - December 1987
Publication Type - Journal Article

Citation: Gavaris, S. and Smith, J. 1987. Effect of Allocation and Stratification Strategies on Precision of Survey Abundance Estimates for Atlantic Cod (Gadus morhua) on the Eastern Scotian Shelf. 7(2): 137-144. https://doi.org/10.2960/J.v7.a16