Physical influences on the stock dynamics of plaice and sole in the North Sea

Abstract

A review of the literature on influences of physical factors on plaice and sole stresses the prominent role of water temperature in all life stages of the species. For plaice, e.g., water temperatures on the spawning grounds are inversely correlated with year-class strength, and growth depends primarily on temperatures. In many instances, however, direct and indirect effects are hard to disentangle and to quantify for use in models, e.g. for stock assessment and prediction (SAP). Hydrodynamic circulation influences the egg and larvae distributions. Existing models reveal the drift variability to be of the same magnitude as year to year variations of larval abundance just before immigration. An improved modelling of the processes could combine recent circulation and transport models incorporating physical/biological properties of the eggs and larvae. It is suggested that future research focuses on this approach. The course of irradiation during spring and its influence on mortality of the 0-groups of both species in the nursery deserves further studies if it is to be useful for SAP.