Evaluation of the reliability of VPA used for stock assessment for TAC species

Abstract

  The reliability of VPA used for stock assessment for the nine TAC stocks was evaluated using Fisher's information matrix and a profile likelihood confidence interval. The confidence intervals for the stock sizes of the Pacific and the Tsushima stocks of Japanese sardine in 2007 were extremely wide. The results also indicated that the confidence intervals for the Pacific stock of club mackerel and the Pacific and the East China Sea stocks of blue mackerel were wide. Uncertainties in stock size estimates should be considered in stock management. The reliability of stock size estimates should be routinely evaluated using the profile likelihood method which is relatively easy to calculate.