One third of each year's production was CWT'd. Otolith marks and scales were used to separate, untagged adult strays returning to the hatchery and separate returning year classes. Seven years of adult returns were monitored to obtain results. One CWT'd brood year at one hatchery showed a significant difference in lower survival from the control group. Recruitment success may be determined by a combination of factors operating at the earliest stages of a fish's life.
Reproductive output is likely to be timed to provide offspring the highest rates of survival.
Egg production was measured by repeated sampling of 150 artificial nest sites. Hydrographic measurements were taken with moored current meters. Spawning and recruitment showed distinct lunar periodicity. Peak spawning of S. partitus occurred after the full moon whereas S. diencaeus peaks after the new moon. Seasonal patterns in spawning output was similar for both species.