Individual variability in growth rate and the timing of metamorphosis in yellowtail flounder Pleuronectes ferrugineus

We studied individual variability in growth and development rates of yellowtail flounder Pleuronectes ferrugineus larvae, and its impact on age and size at metamorphosis. Larvae were reared from hatch to metamorphosis in 3 separate temperature treatments. Temperature influenced the location and distribution of individual transition ages and lengths of larvae reared in separate aquaria, mainly due to its role in determining the mean and range of individual growth rates. Individual metamorphic ages were negatively correlated with the average growth rate of larvae. Individual metamorphic lengths generally increased as mean individual growth rates increased, but higher mean growth also resulted in a wider diversity of lengths. In one of the treatments, the otoliths of the larvae were stained 3 times during the larval period using alizarin complexone, allowing us to reconstruct the growth history of individuals once they had metamorphosed. The body length that larvae had achieved by 2 wk after hatch correlated negatively with the eventual age at metamorphosis. This relationship strengthened the nearer larvae were to metamorphosis. These results were attributed to serial autocorrelations in body length, and to a lesser extent growth rate,or individuals during the larval period. Overall these results suggest that events occurring early during ontogeny that affect the size and growth rates of larvae can impact life history transitions occurring several weeks or months later. As a result, variance in the timing of metamorphosis, which has been suggested as an important determinant of recruitment variability, may become established soon after hatching, and individual probabilities of survival to the juvenile stage may also be determined early on.