Sustainability in single-species population models

Area of Science:

• Ecology
• Fisheries Science
• Population Dynamics

Background:

• The concept of sustainability in fisheries has evolved significantly over decades.
• Early models focused on single-species dynamics and fishing mortality control.
• Contemporary approaches increasingly integrate ecological and socio-economic considerations.

Purpose of the Study:

• To review the historical development of sustainability concepts in age-structured fish populations.
• To analyze the shift from classical to modern and post-modern views of fisheries sustainability.
• To highlight the need for operationalizing new definitions incorporating ecosystem and economic factors.

Main Methods:

• Literature review of fisheries sustainability concepts across four distinct periods: classical, neoclassical, modern, and post-modern.
• Analysis of population models, including deterministic and stochastic approaches with density dependence and depensation.
• Examination of the evolution of management tools, from fishing mortality control to precautionary limits and ecosystem-based objectives.

Main Results:

• Classical sustainability relied on controlling fishing mortality to maintain equilibrium biomass.
• Neoclassical and modern views introduced abundance thresholds and precautionary fishing limits, emphasizing spawning biomass.
• Post-modern sustainability seeks to integrate economic, social, and ecosystem requirements, requiring trade-offs and operational definitions.

Conclusions:

• Fisheries sustainability concepts have progressively incorporated greater ecological and socio-economic complexity.
• Future sustainability definitions must become operational, balancing multiple, potentially conflicting objectives.
• Advances in single-species approaches should be enhanced and combined with multi-species and economic perspectives.