South Fork Nooksack Spring Chinook Population Recovery Project: Seawater Rearing Component

The Manchester Research Station provides seawater rearing for approximately half the fish taken into the South Fork Nooksack Spring Chinook Salmon captive broodstock program.  When fish reared in freshwater at WDFW’s Kendall Creek Hatchery attain size, age, and seasonal criteria for proper smolt development, they are selected for seawater rearing.  Five hundred fish in each year class are transferred to Manchester Research Station, where they are reared in 5 and 6 meter circular tanks on filtered and UV treated seawater during the period they would naturally be at sea.  Each smolt is PIT tagged and fin clipped for DNA analysis for spawning purposes.  Rearing in seawater ranges from 1 - 6 years, depending on age at maturation, with the majority of fish maturing as 4 and 5 year old fish. Each summer maturing adults are identified, via ultrasound technology, and transferred to the Lummi Nation’s Skookum Creek Hatchery for spawning.  Survival in seawater has ranged from 35% - 79%, and growth has been greater than expected, reaching an unusually large size for Chinook salmon in captive culture (4.5 – 9 Kilogram).  The Manchester Research Station has contributed over 500 spawning adults to this recovery effort.