Baffled and Standard Raceways: A Comparison of Juvenile Spring Chinook Salmon Performance and Smolt‐to‐Adult Survival

Abstract

AbstractWe compared on‐station mortality, growth (mm), feed conversion, health parameters, and smolt‐to‐adult survival rate of spring Chinook salmon Oncorhynchus tshawytscha reared in baffled and standard (unbaffled) raceways. Fish reared in baffled raceways survived from release to adulthood at a rate 0.85 times that of fish reared in unbaffled raceways. There was no difference in percent on‐station mortality (range, 0.00–0.001), health, or average length gained (1–12 mm) between fish reared in baffled and unbaffled raceways. Average feed conversion was constant (1.20–2.25) throughout the period of juvenile rearing and was similar between fish reared in baffled and unbaffled raceways, a finding supported by adiposomatic and hepatosomatic indices. Overall, we found similar on‐station performance between fish reared in baffled and unbaffled raceways. The difference between SARs of fish reared in baffled versus unbaffled raceways was not statistically significant (P = 0.08). However, it is suggestive of a biological difference between the two treatments. The self‐cleaning characteristics of baffled raceways free up a substantial amount of hatchery personnel time to attend to other duties, which ultimately reduces the annual operation budget for any facility. In the end, the self‐cleaning feature of baffled raceways needs to be weighed against any advantage in adult survival of fish reared in unbaffled raceways.