Variation in the effectiveness of alternative broodstock, rearing, and release practices
among three supplemented steelhead populations - Hood Canal, WA
Barry A. Berejikian and Megan E. Moore.
NOAA Fisheries, Northwest Fisheries Science Center, Manchester Research Station, P. O. Box
130 Manchester, WA 98353
Ph: 360-871-8301
Email:barry.berejikian @noaa.gov
ABSTRACT
The Hood Canal Steelhead Project is a replicated before-after-control-impact experiment testing
the effects of hatchery supplementation on natural population abundance, productivity and
diversity. The project incorporates two fairly unique practices, hydraulic embryo sampling and
age-2 smolt rearing and release, to minimize hatchery-induced selection on the three
supplemented populations (Dewatto, Duckabush, South Fork Skokomish Rivers). Hydraulic
embryo sampling obviates the need for artificial spawning and associated selection by removing
eggs from natural redds in each river. Embryo collection goals have consistently been met in
two of the three rivers (Dewatto and South Fork Skokomish), and have fallen short each year in
the Duckabush River, largely as a result of high spring flows, which make hydraulic removal
difficult. Survival of natural-origin embryos has consistently averaged above 90% from
collection at the eyed stage to emergence, indicating little damage caused by the hydraulic
sampling method. Control of feed rations and growth rates to produce age-2 smolts has resulted
in a more natural age-at-smoltification than is common for steelhead hatcheries, which nearly all
release fish steelhead at age-1. Size-at-release targets have been consistently met. However,
hatchery-raised steelhead from the South Fork Skokomish River have experienced higher male
maturation rates (approximately 40% of males mature) and greater size variation than the other
two populations (maturation rates typically less than 5%). Three years of acoustic telemetrybased early marine survival estimates indicated that steelhead smolts from one hatchery
(Dewatto and Duckabush populations) survived at rates (freshwater: 88.9%, early marine:
27.4%) similar to the two natural-origin smolts (freshwater: 88.9-97.7%, early marine: 5.714.7%), while smolts from the other hatchery (Skokomish population) exhibited much lower
freshwater survival (43.1-60.2%) and early marine survival (1.9-7.4%). Between-hatchery
differences in rearing density and vessel geometry likely affected survival and behavior after
release and contributed to greater variation between hatcheries than between wild populations.
The effectiveness of ‘progressive’ hatchery techniques should be expected to vary among
populations and hatcheries, especially during initial development.