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Modeling time-varying growth using a generalized von Bertalanffy model with application to bloater (Coregonus hoyi) growth dynamics in Lake Michigan

Emily B. Szalai·Guy W. Fleischer·James R. Bence
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Abstract

A concurrent increase in lakewide abundance and decrease in size-at-age of bloater ( Coregonus hoyi ) in Lake Michigan have suggested density-dependent growth regulation. We investigated these temporal patterns by fitting a dynamic von Bertalanffy model and length–weight relationship with time-varying parameters to mean length- and weight-at-ages (ages 1–7) from annual surveys (1965-–1999). We modeled yearling length, asymptotic size ( L ‰), and the parameters of a power relationship between mean weight and mean length (α and β) as changing slowly over time using a random walk model. The Brody growth coefficient ( k ) was modeled as a linear function of L ‰ with year-specific random deviations. Our results support a positive relationship between L ‰ and k , indicating that under conditions supporting larger asymptotic lengths, individuals approach the asymptote more rapidly. We explored the relationship between year-specific growth parameters and indices of lakewide bloater abundance and found evidence of density-dependent growth. However, in the most recent years, L ‰ and yearling length have remained low in Lake Michigan despite low bloater abundances, suggesting the occurrence of a fundamental shift in the food web.

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Canadian Journal of Fisheries and Aquatic SciencesArticle
90° N90° S · 180° W ← longitude → 180° E
Source-reported bounding extent: 41.61° to 46.05° latitude; -87.91° to -84.95° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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BibTeXRIS

Emily B. Szalai, Guy W. Fleischer, James R. Bence. 2003. Modeling time-varying growth using a generalized von Bertalanffy model with application to bloater (Coregonus hoyi) growth dynamics in Lake Michigan. https://doi.org/10.1139/f03-003

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