A System-of-Equations Approach to Modeling Age-Structured Fish Populations: The Case of Alaskan Red King Crab, Paralithodes camtschaticus

• Published in: Canadian Journal of Fisheries and Aquatic Sciences
• Main Authors: Greenberg, Joshua A., Matulich, Scott C., Mittelhammer, Ron C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1991
• Subjects: Aquatic Science; Ecology, Evolution, Behavior and Systematics; Alaskan king crab; Paralithodes camtschaticus; Red king crab
• Online Access: http://dx.doi.org/10.1139/f91-191; http://www.nrcresearchpress.com/doi/pdf/10.1139/f91-191

This paper presents a simultaneous system-of-equations approach to modeling age-structured populations using trawl survey age/size frequency data. The analysis builds upon a Ricker spawner–recruit structure and provides a cohort-based estimation method that retains the underlying dynamic properties of a delay-difference model. The framework shares a common spawner–recruit function across age-class equations. This exploits the commonality among cohort members and serves as an instrumental variable, lessening the effect of measurement errors in estimation. The dynamic features of the underlying age-structured population are retained through age-specific net survivability and growth parameters that link age-classes. The technique uses multiple observations on a cohort to further mitigate the effect of measurement error and improve overall estimation efficiency. A seemingly unrelated regression estimation method is required to address contemporaneous correlation of errors across age-classes. This framework is applied to trawl survey data for adult male Alaskan king crab, Paralithodes camtschaticus.