230 likes | 248 Views
Learn about the population trends and hatchery production of Snake River Fall Chinook Salmon, including management actions, uncertainties, and future goals. Explore the impact of hatchery releases on abundance and productivity, as well as the challenges and unknown factors affecting the population.
E N D
Snake River Fall Chinook Salmon Productivity and Hatchery Production
What do we mean by “Productivity” • Measure of a population’s ability to replace itself. • “Population growth rate” • “Trend in Abundance” is the manifestation of long-term population growth rate • Incorporates life stage specific survival, fecundity, age structure, and behavior
Presentation Outline • Trends in Abundance • Hatchery Production • Management Actions • Critical Uncertainties
Snake River Fall Chinook Salmon Population and ESU Structure One remaining population Lyons Ferry Hatchery genetics very similar to natural-origin (endemic brood program) Reduced distribution within assessable habitat Two extinct populations Marsing Reach Salmon Falls
Average Adult Returns to Snake River Basin by Decade = Natural/wild Origin = Hatchery Origin
Estimated Return of Fall Chinook Adult Returns to Lower Granite Dam, 1975-2007 Draft Escapement Goal = 39,110 = Natural Origin = Hatchery Origin = Out-of-Basin Hatchery Strays
Abundance and Productivity MetricsICTRT 12-21-06 Draft Assessment
Number of Fall Chinook Redds Counted above Lower Granite Dam, 1988-2007 First Adult Returns from Supplementation
Overall distribution of redds upstream of Lower Granite Reservoir (1988 – 2006 Average ) Imnaha 2.7% Salmon 0.7% Grande Ronde 8.0% Clearwater 24.3% Snake 64.3%
Snake River Fall Chinook Salmon Hatchery Production • Past • Egg bank program – Kalama/Hagerman 1976-1984 • Lyons Ferry releases below Granite 1984-1994 (LSRCP Mitigation) • Present • USvOR dispute, releases above Lower Granite Dam, FCAP acclimation 1995-present • NPTH 2003 – Present • IPC Mitigation • Future • US v OR Agreement TBD
Hatchery Facilities and Release Locations Nez Perce Tribal Hatchery Oxbow Hatchery
Estimated Return of Fall Chinook Adult Returns to Lower Granite Dam, 1975-2007 First Adult Returns from Supplementation ICTRT minimum viability threshold = 2,500
What We Do Know • Increases in abundance and productivity have occurred, but the extent to which those improvements in overall life-cycle survival effects on fall Chinook salmon will be maintained and can be attributed to recent changes in management vs merely reflective of improvements in ocean productivity is uncertain. • Hatchery releases upstream of Lower Granite Dam have increased the abundance of spawners in natal habitat, with assumed contribution to increased production.
What We Do Know (cont.) • Adult abundance via annual run-reconstruction of fish to Lower Granite Dam. • Natural-origin adult abundance near delisting criteria. • Total abundance is well below historic levels and current management goals. • Adult distribution via annual aerial redd counts. • 70/30 rule between Snake and Clearwater. • Mainstem state and tribal harvest via coded-wire tag recoveries and creel surveys.
Things We Don’t Know • Contribution/influence of hatchery fish on natural productivity. • Long-term viability of an ESU with only a single extant population spatial structure and diversity. • Extant and extirpated habitat carrying capacity. • Estimates of annual juvenile abundance / production. • Survival rates for hydrosystem passage routes or operational strategies. • Role of juvenile life history diversity.