The USFWS contract supports two biological objectives for Project 1993-056-00 (Advance Hatchery Reform Science): 1) Improve survival and reduce fitness loss in Columbia River steelhead smolts by minimizing unnatural selection on body size and other smolt characteristics, and  2) Identify behavioral and physiological traits under selection through laboratory-scale research. Objective 1 has been greatly informed by the complementary results of our hatchery and laboratory scale research.  We have demonstrated that the S2 rearing methodologies for steelhead at Winthrop National Fish Hatchery (WNFH) produce smolts with equal or greater survival and faster rates of outmigration than a yearling smolt program.  This has enabled the use of natural origin broodstock at WNFH to reduce genetic impacts of hatchery steelhead on natural origin steelhead.  However, some problems remain, including higher rates of precocious male maturation at WNFH when using S2 rearing than when using S1 rearing.  Project 1993-056-00 has come to the point where we can offer adaptive management solutions for culture regimes that increase the proportion of smolts produced by reducing the number of steelhead that residualize as parr due to insufficient growth and as precociously mature males. In FY 23, Objective 1 will continue an experiment initiated in FY19 with the BY18 year class that compares a new rearing regime for steelhead to the standard S2 rearing regime at WNFH, and will replicate the experiment with the BY 20 and 21 year classes. The new rearing method sorts juvenile steelhead produced from natural-origin broodstock according to their growth rate approximately 8 weeks after ponding to hatchery tanks. The fast growing fish were be raised as yearling (S1) smolts with higher feed rates, while the slow growing fish will be raised using the age-2 (S2) protocols established at WNFH. The split study S1 portion of the experiment has concluded, but the split study S2 component will extend into FY23.  In addition, another study group of BY22 yearling (S1) smolts not sorted according to growth rate will be raised following split study (S1) group feeding regime. We will assess the proportion of smolts and precocious males produced under the new culture method and estimate their survival and travel rate of PIT-tagged fish during outmigration. Results will be compared to the BY20 and BY21 S2 production group (control) at WNFH.  USFWS will support Objective 1 by providing staff and expertise to sort, PIT-tag, mark, and collect pre-release size and smolt assessment data.  USFWS will support Objective 2 by providing steelhead fry from natural origin broodstock to produce the juvenile steelhead required for the laboratory experiments at the NWFSC, Manchester Research Station.