Fishing, reproductive volume and regulation: population dynamics and exploitation of the eastern Baltic cod

摘要: The relative importance of exploitation rate and environmental variability in generating fluctuations harvested populations is a key issue academic ecology as well population management. We studied how the eastern Baltic cod (Gadus morhua) affected by fishing variation using newly developed single species state-space model. Survey data auxiliary were used to estimate model parameters. was then predict future development under different mortalities abiotic conditions. Abiotic condition represented an index: reproductive volume which water suitable (in terms salinity oxygen content) for successful early life stages cod. included direct density dependence, fishing, lagged effect volume. Our analysis showed that approximately three times more important than explaining dynamics. Furthermore, our suggests either under- or over-compensatory dynamics depending on long term catch levels. It follows can reduce increase temporal oscillations stock whether over- undercompensatory, respectively. sustainable level however dependent predicts dual role rate, stabilizing when high destabilizing it low. Exploitation may therefore decrease risk dropping below given biomass reference point conditions, has practical implications fisheries