Research Document 2021/057
Specification of Precautionary Approach Reference Points and Harvest Control Rules in Domestically Managed and Assessed Key Harvested Stocks In Canada
By Marentette, J.R., Kronlund, A.R., Cogliati, K.M.
Abstract
Canada’s Fisheries Act was revised in 2019 to include new Fish Stocks provisions. Updated science guidelines to support the Sustainable Fisheries Framework policies, in particular the Fishery Decision-Making Framework Incorporating the Precautionary Approach (PA Policy), and legal and regulatory requirements are also under development. To inform the development of science guidelines, we reviewed the technical specifications of reference points and harvest control rules for a subset of key harvested stocks, focusing primarily on those domestically managed and subject to the PA Policy.
The adoption of default guidance values of the limit reference point (LRP) and upper stock reference (USR) provided in the PA Policy (0.4 and 0.8 BMSY) is not required, but these values appear to have been widely embraced (43% and 65% of cases, respectively). The USR by definition serves a number of functions, including an operational control point (trigger for management action) to control the risk of approaching the LRP, Healthy-Cautious zone boundary, and target. Science guidelines can provide support for identifying alternative USRs by noting proxies for BMSY (enabling use of proxies for 0.8 BMSY) and by addressing various functions attributed to the USR separately.
Removal References (RRs), like USRs, may serve multiple purposes across the stocks in this review. We found that RR values are consistent with indicating whether harvests are at “approved [target] levels” in a wide range of stocks, and sometimes with limits to be either avoided or with which to characterize acceptable stock status in terms of overfishing on the fishing mortality (F)-axis of the PA Policy. Science guidelines could provide support for identifying RRs by highlighting FMSY proxies and characterization of stock states on the F-axis.
Four broad types of harvest control rules (HCRs) appear to be implemented in Canada: feedback status-based rules, mixed feedback/feed-forward risk-based rules, “constant” rules with no operational control points and feedforward-only objective-based “rules.” The provisional HCR suggested in the PA Policy guidance is not often used although three-part rules with control points at the LRP and USR are common (38% of HCRs). Rules varied widely, although the vast majority are targeted toward informing quantitative output controls (catch limits).
To support the new provisions, the development of updated science guidelines should aim to support easier identification of PA components and more consistent use of terminology for key aspects of the PA Policy, including reference points, operational control points for HCRs, and measurable objectives. The HCR types and other measures will vary widely for fisheries that represent a spectrum of data and assessment model availability for key harvested stocks. As science support may be requested for developing and evaluating a wide range of HCRs, science guidelines will need to address both prospective and retrospective evaluation for an array of possible rules that reflect input and output controls and interact with other management measures.
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