Spatial and temporal effects on the efficacy of marine protected areas: implications from an individual based model

Authored by Aristides Moustakas, William Silvert

Date Published: 2011

DOI: 10.1007/s00477-010-0411-2

Sponsors: United Kingdom Natural Environment Research Council (NERC)

Platforms: C++

Model Documentation: Other Narrative Flow charts Ontologies

Model Code URLs: Model code not found

Abstract

We have developed a spatially explicit model that simulates the interaction between fish and fishers based on past fish location, abundance and fish dispersal. We have examined four scenarios for the design and management of Marine Protected Areas (MPA) and for each we simulated fish biomass and fish catches: (1) No MPA. (2) A single MPA located at a feeding area. (3) A single MPA designed to maximise its overlap with the predominant route of fish dispersal. (4) The use of two MPAs. Each scenario was replicated with two scenarios regarding the time that fish remains within the MPA and two grid map scenarios to account for time-space effects and map/coastline characteristics. Results showed that overall closing an area increased fish biomass. However, an MPA located in the open sea for a limited time may have adverse effects on fish biomass. MPAs increased fish catches when a single large MPA or two small MPAs were located in the open sea for a limited time. The effects of time that fish remains protected in closed areas vary in combination with the spatial design: When examining time effects on the efficacy of MPAs within each scenario with an MPA located in the open sea, fish biomass was always higher in the case where fish was protected for more calendar days during each year. When comparing between different spatial designs, proximity to the coast was a more predominant factor in the efficacy of MPAs rather than time that fish was protected. The scenario that gave the highest total fish biomass was the one that covered the largest part of the migration route, despite increased edge effects. Our results suggest that it is not per se the perimeter to surface ratio that matters, but the trade-off between edge effects and maximised MPA surface in the predominant dispersal direction. Our results also have implications for the design of terrestrial reserves.

Tags

behavior Design Movement patterns Simulation-model Fish Fisheries management Closed areas Reserve networks Hunting disturbance Snow geese