Correspondence among multiple methods provides confidence when measuring marine protected area effects for species and assemblages

Abstract

Abstract Marine protected areas (MPAs) have become a popular tool utilised across global oceans to achieve a variety of conservation goals. Because the reasons for MPA implementation can differ, it is imperative that resource managers design and execute management strategies that allow them to effectively assess MPA performance relative to the goals they set. We compared three MPA monitoring techniques commonly utilised to survey groundfish populations across different depth strata of temperate rocky reef habitat: underwater visual census (0–20 m), scientific hook and line fishing (10–50 m) and baited remote underwater video (30–100 m). We compared the strength and direction of standardised metrics, including response ratios, diversity indices and community structure, examining results through the lens of MPA performance. While each of our monitoring techniques detected similar MPA effects on groundfish biomass and density aggregated across species, MPA effects for individual species varied across methods. Each technique was shown to survey distinct groundfish community assemblages with varying levels of species diversity and richness. Synthesis and applications. While each technique was found to measure similar general trends in marine protected area (MPA) performance over time, we found compelling evidence that the utilization of multiple techniques allows managers to create the most comprehensive, effective and inclusive MPA monitoring regimes.