Modeling deterministic effects of age-structure, density-dependence, environmental forcing and fishing on the population dynamics of Sardinops sagax caerulens in the Gulf of California

摘要: We used an age-structured deterministic model to investigate how population dynamics of Pacific sardine, Savdinops sagax caevuleus, in the Gulf California are affected by age structure, density-dependent recruitment, environmental forcing, and fishing. Density-dependent recruitment had a very strong effect; it stabilized caused mesoscale (4-5 year) cycles abundance. A sinusoidal function was vary survival rates with constant period 60 years various amplitudes. This representation environn~ental forcing long-term abundance similar pattern observed real stocks. linearly increasing fishing schedule over 25 on stock reductions that extended for up 20 years, oscillations 40 after harvest period. The negative impact longer if started when were at their maxima, but biomass decreased most descending node rates. stability analysis indicated sardine is unstable; however, structure included simulations resilient can recover from low levels biomass. theoretical result probably due partly absence stochastic effects our model.