Mind the gap: Estimating misreporting and unreported artisanal landings of the overexploited Chilean hake (Merluccius gayi gayi)

The Chilean hake ( Merluccius gayi gayi ) fishery is a socio-economically important component of the artisanal sector, yet the stock remains chronically depleted despite increasingly stringent management. A key obstacle to recovery is the pervasive uncertainty in fishing mortality, driven in part by Illegal, Unreported, and Unregulated (IUU) activity, specifically misreported and unreported landings. This study quantifies artisanal removals between 2014 and 2024 by integrating scientific observer data from the Fisheries Development Institute (IFOP) with official landing declarations from the National Fisheries and Aquaculture Service (SERNAPESCA) using a novel trip-by-trip matching protocol and non-parametric bootstrap resampling. Our results reveal systematic misreporting (discrepancies between observed and declared landings) and a high prevalence of unreporting (observed trips without a corresponding official record). Reconstructed artisanal landings consistently exceeded official records by a factor of 2.8–5.3, indicating that official systems captured at most one-third of the biomass removed. These findings suggest that historical fishing mortality has been substantially underestimated, and that scientific advice and legal quotas have likely been based on biased catch inputs. We conclude that formal stock assessments should explicitly incorporate the expansion factors estimated here to bring management targets closer to the operational reality of the fishery.