Quantifying the effect of vessel interference on catch rates: A theoretical approach

•We hypothesise that vessel interference makes catch-per-unit-effort (CPUE) a nonlinear function of effort.•We define an interference term, whose magnitude affects trajectories of abundance and CPUE under a simulated buyback.•Our simple model of the vessel interference effect holds across a range of biological and operational parameter values.•Interference appears to be independent of stock carrying capacity, vessel numbers, and relative reduction in vessel number.•Our model provides a promising approach to estimating relative abundance under sudden changes in fishing effort.