Fish Passage above the Dam Title

Sockeye Mitigation

Hatchery Results

The operation of the interim sockeye hatchery at Landsburg since 1991 has provided opportunity to evaluate culture methods that are unique to sockeye culture and test their effectiveness.

Methods that were developed in Alaska to control a viral disease (IHN virus) common to all sockeye populations have proven effective at the Landsburg site. In addition, useful information on incubator performance, water supply, incidence of virus, development rates, emergence timing and other parameters has been generated through the operation of the interim hatchery. This experience is valuable in guiding design and program decisions for the replacement hatchery.

All sockeye fry released from the Landsburg hatchery have been marked since the program began in 1991. These marked fish have provided the opportunity to identify hatchery-produced fish as they grow and ultimately return as adults.

Recovery of the adult carcasses and removal of the marked bone (otolith) in the fish's head provides the basis for determining the origin of the fish through banding patterns that are established during incubation. Otolith marking and sampling have allowed the following analyses to be initiated:

Estimates of annual wild and hatchery sockeye fry production from the Cedar River. WDFW has completed estimates of outmigrants through 1999 and have preliminary estimates for 2000.

Surveys of Bear Creek, a northern tributary to Lake Washington, were done in three years (1998-2000) to determine to what extent hatchery-produced sockeye were straying into that system. The concern is that if the level of straying is too great, that the genetic composition of the Bear Creek sockeye population could be altered. WDFW issued a paper in January, 2001, entitled "Straying by Cedar River Hatchery-Produced Sockeye Salmon to Big Bear Creek, WA" by Kurt Fresh, Steve Schroder, Eric Volk and Jeff Grimm. No Cedar River hatchery marked fish were found among the 1,251 fish that were sampled during the three-year study period.

U. of Washington investigators, using microsatellite loci, have examined the genetic relationships of sockeye and kokanee from the Lake Washington basin and from potential founder populations.

  • Otoliths have been collected from carcasses in the Cedar River each year since 1995. Recent funding to the Washington Department of Fish and Wildlife permitted the otoliths to be read and analyzed. Results from the following analyses are expected to be released soon.
  • Effects on timing and release location of fry on spawning location of adult returns.
  • Survival estimates of wild and hatchery fry
  • Size of adults by sex and by origin
  • Proportion of adult return to the Cedar River originating from hatchery releases
  • Proportion of broodstock that was of hatchery origin

Landsburg Mitigation Contacts

Rand Little, Senior Fisheries Biologist
Seattle Public Utilities
Phone: (206) 684-5925
Email: rand.little@seattle.gov

Paul Faulds, Senior Environmental Analyst
Seattle Public Utilities
Phone: (206) 615-0021
Email: paul.faulds@seattle.gov