One Rule to Rule them All: Hybrid Harvest Control Rules Improve Bio-Economic Outcomes in an MSE Framework

Abstract

Ramped threshold harvest control rules (HCRs), which reduce fishing pressure as a stock declines, are generally resilient to environmental stochasticity, but can struggle to provide good management advice when confronted with abrupt shifts in productivity. For instance, long-lived species with spasmodic recruitment present management dilemmas due to long periods of low recruitment followed by short bursts of extreme productivity, potentially causing market saturation and poor economic conditions. Using management strategy evaluation, we evaluate the performance of a “hybrid” HCR that couples ramped threshold HCRs with stability constraints to limit quota variability and harvest caps to mitigate excessive quota increases, with the goal of identifying whether multiple simple modifications can improve HCR performance for spasmodic species. For long-lived species like Alaskan sablefish, we demonstrate that the hybrid HCR can improve economic value, stabilize catches, and increase population size and resilience compared to a ramped threshold HCR or application of either constraint in isolation. Thus, the hybrid HCR exhibits potential to improve population resilience and harvest opportunity for species with environmentally-driven dynamic recruitment.