A generalization of the three-stage model for advice using the precautionary approach in fisheries, to apply broadly to ecosystem properties and pressures

The six assumptions of the three-stage model for fisheries advice using a precautionary approach are itemized. The general applicability of each is considered for use with any indicator of ecosystem status, or human pressure on the ecosystem indicator, rather than just spawning-stock biomass (SSB) and fishing mortality. The framework is fully generalizable, at least conceptually, without requiring additional assumptions or extensions that are less plausible than the assumptions already made in fisheries applications. However, application of the three-stage framework in fisheries hinges on the existence of some relationship between stock productivity and SSB as the basis for selecting a limit reference point and positioning a precautionary reference point. Three types of relationship can exist in fisheries data, and the framework has strategies for dealing with each. In an ecosystem application, the notion of a relationship between productivity and the amount of an ecosystem feature is sometimes appropriate, but sometimes the response variable may be resilience of the feature to perturbation or tis ability to serve some ecosytem function as a function of the extent of the feature. The generalized framework accommodates all three types of response in five functional relationships, each of which can allow locating a candidate limit reference point.