An MPA Design Approach to Benefit Fisheries: Maximising Larval Export and Minimising Redundancy

Karlo Hock,Nils C Krueck,Colm Tong,Peter J Mumby,Vladimir Tyazhelnikov

doi:10.3390/d13110586

Karlo Hock, Nils C Krueck + Show 3 more

Open Access

https://doi.org/10.3390/d13110586

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Abstract

In the design of marine protected areas (MPAs), tailoring reserve placement to facilitate larval export beyond reserve boundaries may support fished populations and fisheries through recruitment subsidies. Intuitively, capturing such connectivity could be purely based on optimising larval dispersal metrics such as export strength. However, this can lead to inefficient or redundant larval connectivity, as the subset of sites with the best connectivity metrics might share many of the same connections, making them, collectively, poor MPA candidates to provide recruitment subsidies to unprotected sites. We propose a simple, dynamic algorithm for reserve placement optimisation designed to select MPAs sequentially, maximising larval export to the overall network, whilst accounting for redundancy in supply from multiple sources. When applied to four regions in the Caribbean, the algorithm consistently outperformed approaches that did not consider supply redundancy, leading to, on average, 20% greater fished biomass in a simulated model. Improvements were most apparent in dense, strongly connected systems such as the Bahamas. Here, MPA placement without redundancy considerations produced fishery benefits worse than random MPA design. Our findings highlight the importance of considering redundancy in MPA design, and offer a novel, simple approach to improving MPA design for achieving fishery objectives.

Highlights

Population connectivity typically plays a more prevalent role in marine environments than in terrestrial systems [1]
Diversity 2021, 13, 586 where eij is the strength of link from node i to node j, and Ei is the summed out-strength of the site, and move that site from F to R
Our methodology proposes for optimising connectivity in marine protected areas (MPAs)

Summary

Introduction

Population connectivity typically plays a more prevalent role in marine environments than in terrestrial systems [1]. Links between local populations form through the movement of individuals in their larval, juvenile and adult stages. Many organisms, including both habitat-forming corals and fishes, disperse widely during their larval stages in the open ocean. The primary opportunity for dispersal occurs during the larval phase [7,8]. Another key feature of marine environments is that they typically display asymmetric connectivity [9,10,11] because hydrodynamics drive larval movement, rather than pure diffusion [12]. Ocean currents, being highly variable across space, lead to regional larval connectivity patterns with variable strength and directionality [10,13,14]

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