Intensive monitoring
of returning Snake River fall chinook salmon has been a coordinated
effort over the last several years. The cooperating entities were
the Washington Department of Fisheries (WDF), Oregon Department of
Fish and Wildlife, Sez Perce Tribe (NPT), Idaho Power Company (IPC),
U.S. Fish and Wildlife Service (USFWS), National Marine Fisheries
Service (NMFS), U.S. Army Corps of Engineers, and Columbia River Inter-Tribal
Fish Commission. Bonneville Power Administration (BPA) has provided
funds and coordination activities. In addition, the Lower Snake River
Fish and Wildlife Compensation Program (LSRCP) collected and analyzed
genetic data which described the genetic relationships of Lyons Ferry
Hatchery (LFH) fall chinook and mid-Columbia upriver bright fall chinook
through 1990 (Bugert et al. 1990).
When these fish
were petitioned for listing under the Endangered Species Act (ESA),
three major questions were left unanswered:
1. What is the
fate of 50 percent of the adults that have not been accounted for
each year between the counting windows at the first dam on the lower
Snake River, Ice Harbor Dam (IHR) and when they were counted as
they passed the fourth dam, Lower Granite (LGR)? Potential reasons
for this discrepancy include fallback at dams, spawning in the lower
Snake River, or pre-spawning mortality.
2. Why do redd
counts (observed by helicopter survey) on the spawning grounds above
LGR in recent years average only one redd per 8.5 adults passing
the dam? As with dam counts, questions remain regarding the accountability
of salmon upstream of LGR, and the possibility of deep-water spawning
and/or differential spatial spawning distribution between wild fish
and hatchery strays.
3. What is the
stock composition or genetic profile of returning adults and their
offspring above LGR, and how much hatchery straying is occurring?
A study was designed
in 1991 by WDF, in cooperation with the USFWS and Idaho Cooperative
Fish and Wildlife Research Unit (ICFWRU) to answer these questions.
Funding was provided that year by the NMFS, LSRCP, and WDF. Bonneville
Power Administration provided funding the second year. This report
describes the activities and results obtained during 1992.
Two separate but
coordinated methodologies were used in this study. These methodologies
included radio telemetry to address the questions (one and two) of
salmon disposition and accountability while stock identification techniques
were used to address the question regarding stock composition.
We arranged this
annual report into two self-contained chapters entitled:
- Upstream
Passage and Spawning of Fall Chinook Salmon in the Snake River
- Stock Identification
of Snake River Fall Chinook Salmon
