Spatial conservation priorities for marine megafaunal predators: Multi-taxon versus taxon-specific approaches

Abstract

Marine megafaunal predators are globally threatened by anthropogenic stressors, but are key for ecosystem functioning. Their worsening conservation statuses indicate that current management is failing, requiring us to urgently reassess their conservation needs to ensure their survival. Their life histories, threats, and resource needs are diverse. Consequently, spatial conservation areas targeting all species will likely overlook such heterogeneity, contributing to the problem. Here, we model 42 marine megafaunal predator species distributions (marine mammals, elasmobranchs, teleost fishes) in the Mediterranean Sea using available biodiversity data to highlight diversity among species richness gradients for separate taxonomic groups. Secondly, we employ the Marxan spatial planning decision-making tool to identify priority conservation areas for the different taxonomic groups and quantify overlap with the current marine protected area (MPA) system. Different marine megafaunal predator taxonomic groups had heterogeneous distributions, resulting in drastically different spatial conservation priority areas. None of the marine megafaunal predators are sufficiently covered by Mediterranean MPAs (<30% coverage), with marine mammals being the least protected despite having the greatest designated MPA extent, highlighting disconnects between conservation goals and current management outcomes. To conserve marine megafaunal predators, taxon-specific ecological requirements and resulting spatial heterogeneity need to be accounted for in marine spatial planning.