Gamete and Progeny Viability of Summer Steelhead (Oncorhynchus mykiss) Kelts Artificially Reconditioned in a Hatchery Setting

Collection of mature adult anadroumous female and male summer (O. mykiss) spawners from 2006-2010 at Powerdale Dam on the mainstem Hood River. Air spawning and artificial reconditioning was conducted upriver at the Parkdale Fish Facility. Male milt was collected and preserved via cryopreservation, females were air spawned and eggs fertilized with cryopreserved milt and retained for artificial reconditioning. Surviving females were respawned with the same cryopreserved milt. For the 12 individuals that repeat spawned, their performance metrics were compared between the two spawnings using paired t-tests.  Overall, performance metrics were not significantly different between the two spawnings.  Analysis of individual metrics revealed no significant differences among egg production; fertilization rates; fry starting weight; fry starting length; fry growth in terms of length change and weight change. Performance between the female fish that survived and successfully repeat spawned was compared with the total collection of 66 summer-run female steelhead using two sample t-tests.  Results indicated that repeat spawners had higher egg production at their first spawning, compared to the overall collection (p=0.005).  No other significant differences were found. These results suggest that artificial reconditioning likely imparts no negative impact to a repeat spawner's gametes or progeny.