A linked separable–ADAPT VPA assessment model for western horse mackerel (Trachurus trachurus), accounting for realized fecundity as a function of fish weight

• Published in: ICES Journal of Marine Science
• Main Authors: De Oliveira, José A. A., Darby, Chris D., Roel, Beatriz A.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Oxford University Press (OUP) 2010
• Subjects: Ecology; Aquatic Science; Ecology, Evolution, Behavior and Systematics; Oceanography; Darby; Northeast Atlantic
• Online Access: http://dx.doi.org/10.1093/icesjms/fsp290; http://academic.oup.com/icesjms/article-pdf/67/5/916/29136132/fsp290.pdf

Abstract De Oliveira, J. A. A., Darby, C. D., and Roel, B. A. 2010. A linked separable–ADAPT VPA assessment model for western horse mackerel (Trachurus trachurus), accounting for realized fecundity as a function of fish weight. – ICES Journal of Marine Science, 67: 916–930. The western horse mackerel stock covers a large area of the Northeast Atlantic and is characterized by the sporadic occurrence of strong year classes. The only fishery-independent data available for its assessments are the estimates of total annual egg production from triennial egg surveys. Horse mackerel are indeterminate spawners, so a direct conversion of total annual egg production to spawning-stock biomass using prespawning-season estimates of fecundity is not viable. There is also evidence that potential fecundity per kg spawning female increases with fish weight. A linked separable–ADAPT VPA (SAD) model was developed that combines data on total catch, catch-at-age, and total annual egg production with data on potential and realized fecundity to provide population estimates for western horse mackerel. The model accounts for potential fecundity as a function of fish weight and for the development of a targeted fishery on the strong 1982 year class. Simulations confirm that the SAD model is able to reproduce population estimates without bias under a range of scenarios, except where there is a trend in realized fecundity. This underscores the need for improved information on realized fecundity, or alternatively the need to develop management plans that are robust to this source of uncertainty.