Modelling growth and ingestion processes in herring Clupea harengus larvae

We present an individual-based model of growth processes (encounter rates, ingestion, assimilation and metabolism) in herring larvae. The model consolidates existing models on single processes and new experimental results on how temperature and food supply influence growth and survival (starvation) in this species. Environmental forces, such as wind (small-scale turbulence), light, turbidity, temperature, prey-density and -size structure, and intrinsic biological variables, such as larval size, ontogeny (prey-capture and visual capabilities) and starvation (point of no return), are all included in the model. A period just after yolk absorption is recognised when the larvae are particularly vulnerable to reduced food concentrations. Lack of food during this period may limit the development of the visual system and thereby the ability to detect and catch prey. Both experimental results and the simulations demonstrate the integrated effects of prey density, larval development and seasonal progresslon on growth processes. The growth ddference between spring-and autumn-spawned larvae is suggested to be a result of seasonal variations in irradiance. Sensitivity analyses of parameters and submodels are performed.