Eggs of Coho salmon (Oncorhynchus kisutch) were planted in gravel, and placed in open and in covered hatchery baskets in hatchery troughs to determine the possibility of the production of differences in eye diameter by incubation under the different conditions. No significant difference was found between any two of the three lots. In the gravel planting a number of eggs was unaccounted for, which fact may explain the high rates of efficiency obtained by basing estimates of losses in redds only upon the number of dead eggs remaining in the gravel.