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

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.

Assessing the Conservation Value of Artificial and Natural Reefs via Ichthyoplankton Spatio-Temporal Dynamics

“…The differences suggest that the natural reefs in the ESA may serve as breeding grounds for species of the families Scaridae, Labridae, and Mugilidae, whereas the ARs may serve as breeding grounds for the families Lutjanidae, Synodontidae, Carangidae, Fistularidae, and Haemulidae, which indicates the potential of these novel habitats to expand spawning grounds and fish production in the Espiritu Santo Archipelago. This further contribution of the ARs could benefit adjacent fishing grounds through connectivity via the export of eggs and larvae (recruitment subsidies) [55,56], a phenomenon recorded in other artificial reefs around the world [23,57,58]. In addition, the present study highlights the potential attraction effect of artificial reefs on fish larvae, with special attention being paid to mesopelagic species like Benthosema panamense and pelagic species like Cetengraulis mysticetus and Hemiramphus saltator, which do not tend to naturally reside in reef areas.…”