Abstract
The monkfish (Lophius americanus) fishery is an economically important component of U.S. commercial fisheries, yet uncertainty persists in stock assessments due to uncertainty about the species’ biology and variability in fishery-independent surveys. This study develops standardized catch-per-unit-effort indices for the northern trawl and southern gillnet fleets using models designed to account for the strongly right-skewed distribution of monkfish catch data. Logbook and at-sea observer data were processed through detailed exploratory analyses and informed by insights from a series of industry workshops with monkfish fishermen, whose feedback guided data filtering decisions and standardization factors, clarified typical fishing practices, and helped interpret trends in catch rates. The models incorporated key factors such as year, month, depth, fishing area, and vessel characteristics to address non-linear patterns and reduce bias associated with changing fishing behavior. Diagnostic evaluations indicated that the final models adequately met statistical assumptions and effectively standardized relative abundance trends. Results demonstrate long-term declines from peak catch rates in the early 2000s followed by relative stability in recent years for both fleets, suggesting that observed declines in raw catch rates may be driven in part by variability in effort and distribution. These standardized indices provide updated and defensible fishery dependent findings that can be used to support monkfish stock assessment and management.