On the interplay of environmental changes and fishing pressure in exploited fish stocks

Abstract

Fish in many exploited stocks grow faster and mature earlier at either larger or smaller sizes in comparison to pre-exploitation periods. These changes can be driven by both genetic and phenotypic responses. At the same time, these stocks may adjust to other changes of the environment such as increasing/ decreasing overall productivity or changes in temperature. Using a model of planktivorous fish with annual spawning and size- and density-dependent individual growth, we ask if the interplay of environmental change and fishing pressure could lead to stabilizing, disruptive or directional selection on age and size at maturation in the stock. This question is particularly relevant for habitats exposed to significant directional change in the environment, the prime example being many man-made inland reservoirs.