Technical considerations for stock status and limit reference points under the fish stocks provisions

Abstract

Revisions to Canada’s Fisheries Act have resulted in a need for a single limit reference point (LRP) and metric of stock status for major fish stocks prescribed by regulation. The Science Sector has identified a need to provide guidance to estimate LRPs and stock status for scenarios that presently do not meet the “one stock, one LRP, one status” requirement, and a more general need for guidance on methods to estimate and report both LRP and stock status across a spectrum of data and knowledge availability and quality. To inform this guidance, we provide a review of literature and approaches to defining LRPs, describe technical considerations for choosing from various approaches for estimating LRPs and indicators of stock status across the data spectrum, and provide technical considerations and guidance for estimating a single LRP and metric of stock status in cases where either a single assessment model or multiple models are applied. We review methods to estimate BMSY and B0; theoretical, historical, and empirical proxies for these indicators; and some generic “rules of thumb” for other common LRPs used in Canada. We also provide examples of less common indicators, LRPs, and stock status estimation methods that may be applicable across the data spectrum, and review approaches with which to address volatility in stock status indicators. We provide operational and technical considerations as a basis from which to select or reject various candidate indicators and LRPs as well as options and considerations for reporting a single status per stock in an assessment or stock status update, and across advice and management frameworks.