The USFWS contract supports two 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.

In the FY24 performance period, staff of the USFWS will collaborate with NOAA on the following activities in support of the two project objectives.

Objective 1:
During the FY23 performance period data collection for a four broodyear hatchery-scale experiment of split-age rearing was completed at the USFWS WNFH.  In FY24 the USFWS will support the collaboration with NOAA by providing assistance in consolidating PIT tag detections and covariates for all PIT tagged fish by broodyear and rearing group to be used in survival and travel time analyses.  The USFWS will construct an additional data set of gonado-somatic index (GSI) for the maturation assessments conducted at the beginning and end of volitional release.  These two data sets will be analyzed to compare the efficacy of split-age and fixed age rearing methods for increasing survival, promoting smoltification and decreasing the rate of precocious male maturation.  Finding an effective rearing method that maximizes smoltification without accelerating maturation is key to reducing domestication which is strongly associated with fitness loss of hatchery reared steelhead.  The USFW service will collaborate in the production of manuscripts once the data analysis is completed.

Objective 2:
Initial results from the recently completed split-age rearing experiment at WNFH indicate that precocious male maturation in age-2 rearing treatments remains elevated even after splitting juvenile fish according to their growth rate.  Overall, the split-age rearing method did reduce the total rate of male maturation for a given broodyear because precocious male maturation was virtually non-existent in the half of the broodyear reared to smolt at age-1.  However the half reared as age-2 smolts had similar rates of male maturation as the fixed age-2 rearing group.  Interestingly, in the companion laboratory studies at the Manchester Research Station the rates of smoltification were greater and rates of male maturation were much lower than in the hatchery-scale study at the WNFH; both studies were conducted on the same natural-origin steelhead broodstock,  A major difference in rearing conditions between studies was rearing vessel geometry; the laboratory studies were conducted in circular rearing vessels, and the hatchery-scale studies were conducted in rectangular concrete raceways.  
Infrastructure upgrades are scheduled for the WNFH and include replacement of some aging concrete raceways with large circular rearing vessels. If rearing in circular tanks improves smoltification and reduces maturation, as seen at the laboratory scale, the new circular tanks at WNFH may also improve survival and reduce fitness loss in these populations of summer steelhead. The USFWS will support Objective 2 by providing insight and technical assistance in determining the feasibility of installing temporary circular tanks within the existing infrastructure of WNFH to support a pilot-scale circular tank experiment at WNFH.  Beyond identifying a suitable location at the WNFH and required materials, The feasibility study will include what changes need to be made to rearing conditions and protocols including: tank size, flow rates, stocking density, cleaning methods, freeze protection, and feeding regimens.  In FY24, the USFWS will continue to provide summer steelhead for laboratory research efforts conducted at the NOAA Manchester Research Station.