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

We 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.