Is there a relationship between fluctuating asymmetry and reproductive investment in perch (Perca fluviatilis)?

Fluctuating asymmetry (FA), or random deviation from perfect bilateral symmetry, is often used as an indicator of perturbed development. Several studies attempt to correlate FA with components of individual fitness or population viability. In this study we test for a correlation between FA and four fitness traits in female Eurasian perch (Perca fluviatilis) inhabiting acidified or non-acidified lakes. Three bilateral meristic characters were counted on each side of the fish: number of gill rakers on the lower first branchial arch, number of gill rakers on the upper first branchial arch, and number of pectoral-fin rays. An asymmetry index summarizing the numbers of asymmetric characters per fish was also calculated. Four traits related to fitness were measured: gonad dry mass, egg mass, gonadosomatic index, and fecundity. There were significant differences in FA among the five perch populations for the characters number of pectoral-fin rays and number of upper gill rakers, and also for the FA index. Asymmetry was generally greater in perch living in acidified lakes than in those in non-acidified lakes. However, there was no significant correlation between FA and any of the four fitness-related traits within populations. Therefore, asymmetry in the traits measured here may not be a good indicator of individual fitness in perch.