Sockeye salmon fry were collected from the Fulton River spawning channel at Babine Lake, British Columbia [Canada], in May 1978. The fish were reared for 26 d [day] in enclosures in the spawning channel and were sampled every 7-10 d. The sagittae were removed from 25 fish from each sample, and the growth rings in 1 otolith from each fish were counted. A regression of the number of rings on the number of days since capture showed that these rings are, on average, formed daily beginning at the time of emergence. A number of possible technical and biological causes of variation in ring counts within and between samples are considered.