View uncertainty details

UncertaintyWhat is the spawning escapement or harvest rate (range), accounting for hatchery and natural fish and nutrient return, needed to sustain productive fish populations and fish harvests in the future? What is the biological goal for spawning escapement?
ThemeHarvest
SubthemeTarget reference points
Sources
Criticality Level Priority
Rationale This knowledge is needed to understand if escapements are sufficient to achieve the Fish and Wildlife Program's Appendix D Goal 13: "Achieve full mitigation for anadromous fish, native resident fish, and wildlife losses by restoring healthy, self-sustaining, and harvestable, natural-origin anadromous fish….and resident fish." A biologically based spawning escapement goal is the number of spawners required to potentially maximize the average harvest or return for a specific population in the foreseeable future. Knowledge and application of biologically based spawning escapement goals are fundamental to sound harvest and hatchery management. Where possible, biological escapement goals should be based on stock recruitment curves (i.e., the relationship between parent spawning escapement and the abundance of their progeny). These goals, which consider productivity and carrying capacity of the population (See Programmatic Comment 6; ISAB 2015-1), can be used to evaluate effects of harvests on fish populations (or stock management units) and to identify when observed spawning escapements are too low, adequate, or too high. The biological goals should also consider (1) pHOS guidelines developed by the Hatchery Scientific Review Group (HSRG) and (2) if spawner abundances in excess of carrying capacity are needed to support ecosystem function. Some biologically based goals already exist in the Basin, but many more could be developed.

last updated: Jan 27, 2016