Implications for current management advice for North Sea plaice ( Pleuronectes platessa L.): Part II. Increased biological realism in recruitment, growth, density-dependent sexual maturation and the impact of sexual dimorphism and fishery discards

Abstract

Since the early 20th century there have been many descriptions of variability in the growth and sexual maturation of North Sea plaice, both through time and between the sexes. There have also been large changes in plaice abundance and recruitment against a background of increasing fishing pressure and changing environmental conditions. This paper evaluates the importance of sexual dimorphism, trends in growth and recruitment, density-dependent sexual maturation and discarding and considers their implications for current stock assessment and management practice. Density-dependent sexual maturation may be important at low stock levels by providing resilience to stock collapse. The productivity of the stock varied over a time scale of 10–15 years. Discarding of small fish by the fishery can have a substantial influence on the productivity of the stock and bias our perception of both productivity and stock size, and has major implications for the management of North Sea plaice.