Sockeye Mitigation

Sockeye Broodstock Collection Practices

The current sockeye hatchery is designed to incubate 18 million eggs. The adult sockeye for the hatchery were collected at a weir at river mile 6.5 (Cavanaugh Pond) from 1992 to 2007 (inclusive). In 2008 the broodstock collection weir was relocated to river mile 1.7, just upstream of I-405.

Due to concerns about potential impacts to adult Chinook salmon moving up the Cedar River to spawn, the Cedar River sockeye broodstock weir is operated with a protocol to avoid impacts to Chinook salmon. Chinook that move upstream and enter the trap are passed upstream of the weir. Observations are made of fish in the river below the weir. If Chinook appear to be holding below the weir, the weir is opened to allow the Chinook salmon to freely pass upstream. When the Chinook have passed upstream the weir is closed. If sockeye salmon are not being collected for the hatchery, the weir and trap are opened up to allow all fish to freely pass upstream of the weir. During the Chinook migration the weir often remains open all night.

Largely due to the protective operation of the weir for Chinook, and recent high runs of Chinook salmon returning to the Cedar River, the collection of sockeye broodstock has fallen short of the 18 million egg collection goal. In 2007 and 2008 only 1.7 and 2.9 million sockeye eggs (respectively) were collected from the adult sockeye collected at the broodstock weir.  The sockeye return in 2008 was the lowest return since counts were started in 1972 at the Ballard Locks.  The new weir is of a different design, and located lower in the Cedar River. The new weir location addresses genetic concerns, in addition to improving the ability to collect sockeye broodstock. The new weir is operated in a similar manner, as the previous weir, to protect Chinook salmon.  Additional monitoring will be conducted to assess affects on Chinook salmon. Operation of the weir will be modified to avoid impacts to Chinook.

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