A flexible decision support tool for MSY-based MPA design

Abstract

ICES WGEF recommends that demersal elasmobranchs be managed using spatial proxies 11 for Maximum Sustainable Yield. Here we combine escapement biomass – the percentage of the stock which must be retained each year to conserve it – with maps of predicted abundance of four ray species (cuckoo, thornback, blonde, and spotted), created using Boosted Regression Tree modelling. We then use a Decision Support Tool to generate location and size options for MPAs to protect these stocks, based on the priorities of the various stakeholders, notably the minimisation of fishing effort displacement. Variations of conservation/fishing priorities are simulated, as well as differential priorities for individual species, with a focus on protecting nursery grounds and spawning areas. The result is a complete software package that produces maps of predicted species abundance from limited survey data, allowing disparate stakeholders and policymakers to discuss management options within a mapping interface.