Phenotypic Variability in Fish Populations and Its Representation in Individual-Based Models

The representation of individual variation in fish populations by individual-based simulation models is examined. A framework is provided for assessing the fundamental features of phenotypic variability and examples are given of variation in early life history traits of fishes. The genetic components of phenotypic variability and the pattern of covariation between life history traits are features that have yet to be satisfactorily represented in these models. This limits analysis of long-term effects of trait-biased mortality such as might be caused by a size-selective fishery. Consequences of neglecting these features will become increasingly evident as these models extend from young of the year to transgenerational configurations. The use of estimates of traits and processes derived from population- and species-level data in individual-based models is also considered. It is concluded that estimates from aggregated data cannot be assumed to represent individual-level processes. From these consid...