Stochastic Dynamics of Dual-Prey–Predator Interactions under Harvesting Pressure: Insights from the California Current Ecosystem

This study presents a stochastic predator-prey model involving two harvested prey species—sardines and anchovies—and a common predator, the blacktip shark, under the influence of environmental noise. The model incorporates Holling type-II functional responses, harvesting efforts, and white noise perturbations representing environmental variability. Analytical investigations determine the boundedness and stability conditions of equilibria. Numerical simulations reveal that the predator population is highly sensitive to stochastic perturbations, particularly the noise intensity associated with predator mortality. Notably, a sufficiently large noise intensity in anchovy dynamics (α₂ > 72.06) can stabilize the coexistence equilibrium, where higher values of α₁ and α₂ tend to destabilize the system. Phase portraits and bifurcation analyses illustrate the effects of harvesting rates and noise intensities on species persistence and extinction. These findings highlight critical thresholds for sustainable harvesting and noise tolerance, offering ecological insights into species coexistence within the California Current ecosystem.