Maternal size, not age, influences egg quality of a wild, protogynous coral reef fish Plectropomus leopardus

Abstract

Maternal effects are widely known to influence early life-history traits of offspring, including egg and larval quality. We studied the relationships between maternal length, weight, age and hepatosomatic index, with indicators of egg quality (egg size, oil droplet size, total lipid content and lipid classes) of a wild, protogynous reef fish, the common coral trout Plectropomus leopardus. Of the egg wet weight, 3% was lipids, with the neutral lipids, triacylglycerol (34% of total lipids) and wax esters (40%), being the main source of lipid energy within the egg. Polar lipids comprised 24% of total lipid content. Egg size and oil droplet size increased positively with maternal weight, and egg size increased positively with maternal length (p < 0.05). None of the variation in total lipid or triacylglycerol content was explained by the maternal traits we examined, but the proportion of long-term storage lipid wax esters increased with maternal length and weight (p < 0.05). Maternal age had no effect on any indicators of egg quality. Hepatosomatic index influenced sterols, although only with fish weight (p < 0.01). Our study highlights the variability in egg characteristics of a protogynous fish in the wild, and provides a greater understanding of variation in maternal traits as indicators of egg quality for teleost fishes. Our results suggest that offspring from larger females may have an advantage during the critical transition to successful exogenous feeding through enhanced provisioning, and that size-truncation through fishing may have negative consequences for recruitment and replenishment of P. leopardus populations.