Maternal contribution to spawning and early life-history strategies of the genus Lepidonotothen (Nototheniidae, Perciformes) along the southern Scotia Arc

Abstract

The coastal fish community of the southern Scotia Arc, including the South Shetland Islands and the Bransfield Strait, is composed of the genus Lepidonotothen, which consists of three widely overlapping species such as L. kempi, L. larseni and L. nudifrons. The life-history strategies of these species driven by environmental and inter-specific interactions remain poorly known. In this paper, we estimate the maternal contribution to spawning of adult females in terms of fecundity and egg size through macroscopic and histological analyses of gonads. We further investigate the size and timing of hatching, growth rate and duration of the larval stage through microstructure analysis of sagittal otoliths collected from larval samples. All three species produced eggs of relatively small size at hatching, showing a trade-off between egg size and fecundity. Total fecundity was positively related to fish size during growth, as well as to maximum size. Female gonad investment was comparable among the species, as they all start spawning at about 65% of their maximum size with a similar gonadosomatic index. All species generated small larvae (altricial) which hatched over widely different periods, resulting in a temporal succession of larval occurrence. Compared to L. kempi, the other two species had relatively slow-growing larvae. Only L. kempi and L. larseni produced overwintering larvae. Differences in maternal contribution to spawning and early life-history traits of these species contribute to reduce interspecific competition for food through ecological niche partitioning.