Reading the footrope: Operational efficiency and handling time in the pelagic pollock trawl

On the eastern Bering Sea shelf, high-value pollock school near bottom, and captains track footrope height in real time to fish as close to them as substrate allows. Bycatch concern is seasonal: Chinook salmon in the A-season (January–April), chum salmon in the B-season (June–October). Eighteen years (January 2008 through the 2026 A-season) of NMFS observer records and VMS data quantify the operational cost of fouling events and characterize captains’ response. After “no problem”, the most frequent gear performance code is “caught crab pot”. Pot encounters are found within 87% of the trawl fishing grounds; encounter probability is mapped using a logistic generalized additive model. Hurdle generalized linear mixed models with management season as a fixed covariate are fit to nine co-occurring species, separating pot-encounter effects on bycatch encounter probability from catch intensity. Pot-encounter hauls are 39% less efficient at catching pollock per km² swept, the per-haul codend deficit is ~15%, and recovering that deficit requires ~17% additional towing effort. Bycatch responses split along a habitat-use axis: the three pelagic species (chum salmon, Chinook salmon, Pacific herring) are caught less on pot-encounter hauls (reduced gear efficiency signal), while demersal and benthic species (Pacific cod, Pacific halibut, three shelf sole species) are caught more (substrate-exposure signal). Results identify spatial avoidance, operational, and derelict-gear management levers that could reduce the frequency and per-event cost of trawl–pot interactions.