Adapting the sampling design of research surveys to improve the biomass estimation of secondary species—the case study of <i>Raja clavata</i>

Abstract Research surveys are important to evaluate fishery resources’ spatial distribution and abundance. Although the underlying sampling is usually conceived with a focus on specific species, efficient designs can also collect data secondary species. We present framework explore adequacy of alternative for research aiming maximize accuracy estimates species abundance while maintaining quality primary A geostatistical model-based approach was developed considering semi-continuous nature excess zero values commonly observed New were defined according optimization weights evaluated based resulting prediction exactness. The applied bottom trawl survey conducted along Portuguese continental coast European hake, Merluccius merluccius, as thornback ray, Raja clavata, design URSI provided best balance between both methodology be replicated other an extended set recommend that decision which adopt in future should consider cost-efficiency analysis.