Integrating the US Caribbean Reef Fish Visual Census into fishery stock assessments

Abstract

The United States Caribbean Reef Fish Visual Census (RVC) is a fishery-independent survey of the coral reef fish community, comprised of hundreds of species, designed to provide quantitative information for data-poor fisheries to support regional stock assessments. The Caribbean RVC, implemented in 2014 as part of the National Coral Reef Monitoring Program (NCRMP), uses a probabilistic stratified random sampling design capitalizing on the strong mean-variance relationship of population abundance dependent on hardbottom habitats and depths. Here we highlight RVC data for queen triggerfish in Puerto Rico, where survey precision improved from CVs of 20.6% in 2014 to 12.6% in 2021, which produced accurate and cost-effective estimates of key assessment metrics like size- structured relative population abundance and biomass. We estimated a relatively stable exploited-phase average population abundance for 2014–2021 at 2.3 million queen triggerfish with a biomass of 1246 metric tons. To support stock assessments using "statistical catch at age" models, we generated a 2001–2021 time series of several population metrics by a statistical conversion of spatially-restricted, pre- NCRMP data to the RVC frame. To cross-check assessment modeling, we combined 2014–2021 RVC results with life history demographics in an alternative length-based risk analysis (LBRA) model to evaluate stock sustainability consequences using two lifetime growth scenarios. LBRA models indicated low overfishing risks. We concluded that only a few quality fishery-independent surveys are needed to obtain understanding of stock sustainability status, and that RVC not only provides reliable data for single-species stock assessments, but also for design evaluation of marine protected areas and ecosystem-based fishery management.