Assessing Environmental Impact on Mass Balance, Carrying Capacity and Growth of Exploited Populations

Population models that have been applied.for assessment o.f exploited populations are also useful for assessment of environmental impacts. Surplus production models have been applied.for both fishery and environmental impact assessment; environmental impacts with three different modes ofaction can be incorporated into the surplus production model. For each of these possible modes of action the equilibrium relations among biomass, yieM, level o.f.[ishing and level of environmental stress are developed. The resulting equations are applied to describe the results of laboratory experiments in which exploited populations were manipulated to alter the growth coej~'cient, carrying capacity, or mass balance. The models describe the experimental results. INTRODUCTI ON Surplus production models have been widely applied for assessing the impact of fishing on fish populations and to determine optimum levels o