Enhancing cost-effectiveness in marine recreational fishing assessment: Flexible model-based estimation of participation rates and effort

Marine Recreational Fisheries (MRF) is a widespread leisure activity with significant ecological and economic implications in coastal regions worldwide. Obtaining accurate estimates of its size is hindered by the dispersed spatial and temporal scales at which recreational fishers operate. Conventional survey-based methods require significant time and financial resources, limiting their application. We provide a new approach for estimating the size of MRF, using a Generalized Additive Model (GAM) hurdle specification, which offers advantages over traditional methods, allowing both estimation in unsampled areas and a more refined spatial resolution. Leveraging a dataset comprising over 16,000 observations from a telephone survey representative of Italy, we find that in our application the GAM provides a better fit than parametric alternatives. Our analysis estimates that 1.5 million individuals engage in MRF in Italy, constituting approximately 2.6 % of the national population, generating 34 million annual fishing trips. Simulation results suggest that our proposed approach remains informative even with smaller sample sizes. We show that a model-based approach could alleviate constraints in MRF estimation, particularly where financial resources are limited. This represents a step forward for incorporating MRF into policies aimed at supporting the health of marine ecosystems.