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Free keywords:
GADUS-MORHUA; RECRUITMENT MODELS; MARINE RESERVE; SEA; CLIMATE;
SURVIVAL; WATER; TEMPERATURE; CIRCULATION; MIGRATIONBaltic cod; climate change; environmental variability; reproductive
volume; population dynamics; management; policy; age-structured model;
temporal marine reserve;
Abstract:
The population dynamics of the Eastern Baltic cod (Gadus morhua callarias L.), unlike many other stocks, shows a strong dependency on environmental conditions. To test the implications of different management policies on the stock and the fishery in a system of global environmental change, we apply a spatially disaggregated, discrete time, age-structured model of the Eastern Baltic cod stock in 50 year simulation analyses. The simulation provides;in analysis of stock, yield, and revenue development under various management policies and environmental scenarios. The policy analysis, focusing oil different regulations of fishing mortality, is embedded into three environmental scenarios, assuming low, medium, or high climate and environmental change. The environmental assumptions are based on simulation results from a coupled atmosphere-ocean regional climate model, which project salinity in the Baltic Sea to decrease by 7-47% in the period 2071-2100 relative to the reference period 1961-1990. Our simulation results show that a significant reduction in fishing mortality is necessary for achieving high long-term economic yields. Moreover, under the environmental scenarios presented, a stock collapse cannot. be prevented. It. can, however, be. postponed by the establishment of a marine reserve in ICES subdivision 25.
