Frank Thrower
Auke Bay Laboratories
Alaska Fisheries Science Center, NOAA Fisheries

Ted Stevens Marine Research Institute
17109 Pt Lena Loop Rd
Juneau AK 99801
(907) 789-6055
Frank.Thrower@noaa.gov

Research on population structure and genetics of steelhead populations began at Little Port Walter (LPW) in 1996 with a project funded by the NOAA Fisheries Office of Protected Resources. This project focuses on the effects of inbreeding and outbreeding depression on important life history characteristics such as: survival during various stages from embryo to adult, growth rate, age at maturation, and proportion of juveniles that migrate to sea (smolts).

Another important aspect of this research is to determine the suitability of maintaining endangered populations of steelhead in a wild state but completely in a freshwater environment for decades until their natural habitat with seawater access can be restored.

Several genetic tools are currently being used to describe the genetic composition of the wild steelhead population in Sashin Creek at Little Port Walter and the rainbow trout population in Sashin Lake which was established by a transplant of fish from the anadromous part of the creek to the lake in 1926. The lake had been barren of fish to that time and blocked from anadromous migration by two large waterfalls. Genetic profiles have been developed using allozyme markers, mitochondrial DNA markers, and microsatellite markers. Inheritance research has been done on many newly developed microsatellite markers to determine their utility for genetic profiling. This new genetic information, coupled with the adult weir on Sashin Creek and a new trap for the collection of downstream migrant smolts and adults, will provide more information useful in the determination of Endangered Species Units and the ecological risk of extinction of small steelhead populations. No other wild steelhead system in the United States has this complete capability.