Effects of Marine Protected Areas on Overfished Fishing Stocks with Multiple Stable States

TL;DR

This paper uses a mathematical model to explore how marine protected areas influence overfished stocks, revealing that their effectiveness depends on species migration and management policies, with potential for positive, negligible, or negative impacts.

Contribution

It introduces a model demonstrating that MPAs can have varied effects on fish stock recovery, emphasizing the importance of species behavior and planning in MPA effectiveness.

Findings

MPAs can either aid or hinder stock recovery depending on migration patterns.

MPAs reinforce resilience for migratory species.

Poorly planned MPAs may reduce fish stock recovery or worsen conditions.

Abstract

Marine protected areas (MPAs) have attracted much attention as a tool for sustainable fisheries management, restoring depleted fisheries stocks and maintaining ecosystems. However, even with total exclusion of fishing effort, depleted stocks sometimes show little or no recovery over a long time period. Here, using a mathematical model, we show that multiple stable states may hold the key to understanding the tendency for fisheries stocks to recover because of MPAs. We find that MPAs can have either a positive effect or almost no effect on the recovery of depleted fishing stocks, depending on the fish migration patterns and the fishing policies. MPAs also reinforce ecological resilience, particularly for migratory species. In contrast to previous reports, our results show that MPAs have small or sometimes negative effects on the recovery of sedentary species. Unsuitable MPA planning might result in low effectiveness or even deterioration of the existing condition.