Identifying covariates for CPUE standardization in data-limited recreational fisheries: commercial passenger fishing vessel fisheries for largehead hairtail Trichiurus japonicus in Tokyo Bay

Abstract Recreational fishing is a major user of fishery resources alongside commercial fisheries. However, its operational characteristics remain poorly understood, and quantitative analyses have been limited. In Japan, recent amendments to fisheries legislation have promoted science-based resource management, highlighting the urgent need to improve data availability for recreational fisheries, particularly for catch and effort. In this study, we analyzed commercial passenger fishing vessel fisheries (CPFVFs) targeting Trichiurus japonicus in Tokyo Bay, where catches by commercial and recreational sectors have increased. To identify covariates relevant to catch per unit effort (CPUE) standardization, we analyzed SNS catch reports and constructed models to explain per-angler catch variation. The selected model retained environmental and operational covariates. Some covariates, such as month and water temperature, may contain abundance-related signals; whereas others, such as day of the week, seating position, angler density, fishing gear, and vessel-related effects, probably represent non-abundance-related variation to be controlled for in standardization. Mean tidal range, moon phase, and rain were interpreted as ambiguous covariates that may reflect both abundance-related and non-abundance-related processes. These results indicate that recreational catch rates should be interpreted within a CPUE standardization framework and provide a basis for incorporating CPFVFs into science-based stock assessment and management in data-limited coastal systems.