Performance of Spring Chinook Salmon Reared in Standard Raceways and in Michigan Raceways with Oxygen Supplementation

Abstract

AbstractThe decreasing availability of freshwater means that fish culturists must seek ways to increase production efficiency, that is, the number of fish produced from a given volume of water. This paper summarizes a comparison of the performance of yearling spring Chinook salmon Oncorhynchus tshawytscha reared in standard raceways and those reared at higher densities in Michigan‐style raceways with oxygen supplementation (to conserve water). During rearing at the Umatilla Fish Hatchery in northeastern Oregon, water temperatures and pH were similar between the two raceway types, but dissolved oxygen was higher and un‐ionized ammonia levels were lower in the Michigan raceways. No disease outbreaks requiring medicine occurred in either raceway type. Before transfer to acclimation facilities on the Umatilla River, the average fish size differed by more than 3% between raceway groups and average Fulton's condition factor never differed by more than 3%. After fish were released into the river, we monitored out‐migration travel times and survival to John Day Dam on the Columbia River using implanted passive integrated transponder tags in a randomly subsampled group from each raceway. No significant difference in travel time was detected between the two raceway types; however, average survival probabilities to the dam favored the standard rearing strategy. We used recoveries of coded wire tags implanted into juvenile fish before river release to estimate smolt‐to‐adult survival rates, the numbers of adults produced annually, and adult production efficiency (adults produced · L−1 · h−1) between the two raceway types. Although survival rates were significantly higher for Chinook salmon reared in standard raceways, there was no significant difference in the average number of adults produced per raceway series, and production efficiency significantly favored the Michigan raceway group. These results indicate that limited water supplies can be used more efficiently by rearing spring Chinook salmon in Michigan raceways with oxygen supplementation rather than in standard raceways.