Evaluation of a Revised Hatchery Method Tested on Pink and Chum Salmon Fry

An artificial incubation method employing filtered river water and a gravel substrate was compared with natural propagation in a test on pink (Oncorhynchus gorbuscha) and chum (O. keta) salmon, at Hooknose Creek, King Island, B.C. At time of migration, about 70% of the hatchery pink fry were similar to the wild fry in stage of development; the remainder were immature. A similar but less pronounced difference occurred in the chum. Average rates of development were the same in the hatchery and the creek for each species. These two phenomena combined resulted in the hatchery fry of both species migrating, on the average, from 1 to 2 weeks earlier than the wild fry.Growth during incubation was the same in hatchery and creek, i.e., no loss of potential size occurred in this hatchery environment. Survivals in the hatchery were higher than in the creek, but were less than expected on the basis of experiments carried out elsewhere. Hatchery pink fry showed a lower variability in mean lengths and weights than did creek fry, possibly in response to greater homogeneity of the incubational environment. Chum fry from the last part of the creek runs showed evidence of postemergent growth in fresh water.