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<p>Forage fish play a crucial role in aquatic food webs by transferring energy from lower trophic levels to piscivorous fish and supporting economically important fisheries. In this study, we develop an eco-epidemiological forage–piscivorous fishery model incorporating disease transmission, harvesting, schooling behavior, and a forage fish-induced variable carrying capacity. Our results show that disease prevalence, harvesting pressure, and environmental feedback jointly regulate species persistence, ecosystem stability, and the risk of population collapse. More specifically, whereas favorable environmental conditions support the long-term maintenance of both forage and piscivorous fish populations, excessive harvesting and unfavorable ecological conditions may cause sudden regime shifts, hysteresis, bistability, and loss of coexistence. Mathematical analysis reveals critical ecological thresholds through Hopf, saddle-node, and backward bifurcations, while numerical investigations uncover Neimark–Sacker, period-doubling, zero-Hopf, Bogdanov–Takens, and homoclinic bifurcations, highlighting the rich dynamical structure of the system. Furthermore, environmental stochasticity can substantially alter persistence and extinction outcomes and may facilitate disease eradication under suitable conditions. These findings demonstrate how disease, harvesting, and environmental variability interact to shape the long-term dynamics of aquatic fisheries and provide valuable insights for preventing undesirable regime shifts and supporting ecosystem-based fishery management.</p>

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Stochastic shift and dynamical complexities of a disease-induced forage and piscivore fishery model

  • 期刊论文

  • 发表日期：

    2026年7月21日

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  • Tanuja Begam,
  • Soumita Sen,
  • Samares Pal

摘要

Forage fish play a crucial role in aquatic food webs by transferring energy from lower trophic levels to piscivorous fish and supporting economically important fisheries. In this study, we develop an eco-epidemiological forage–piscivorous fishery model incorporating disease transmission, harvesting, schooling behavior, and a forage fish-induced variable carrying capacity. Our results show that disease prevalence, harvesting pressure, and environmental feedback jointly regulate species persistence, ecosystem stability, and the risk of population collapse. More specifically, whereas favorable environmental conditions support the long-term maintenance of both forage and piscivorous fish populations, excessive harvesting and unfavorable ecological conditions may cause sudden regime shifts, hysteresis, bistability, and loss of coexistence. Mathematical analysis reveals critical ecological thresholds through Hopf, saddle-node, and backward bifurcations, while numerical investigations uncover Neimark–Sacker, period-doubling, zero-Hopf, Bogdanov–Takens, and homoclinic bifurcations, highlighting the rich dynamical structure of the system. Furthermore, environmental stochasticity can substantially alter persistence and extinction outcomes and may facilitate disease eradication under suitable conditions. These findings demonstrate how disease, harvesting, and environmental variability interact to shape the long-term dynamics of aquatic fisheries and provide valuable insights for preventing undesirable regime shifts and supporting ecosystem-based fishery management.