Does otolith chemistry indicate diadromous lifecycles for five Australian riverine fishes?

Abstract

Diadromy is an important characteristic of the lifecycle of many Australian coastal fishes, but many of these species remain poorly studied. The migratory patterns of five riverine fish species from south-eastern Australia were examined using otolith chemistry. Analyses of individual otoliths from wild-caught fishes revealed distinctive lateral variation in otolith Sr : Ca values that provide good evidence for an amphidromous lifecycle for two species: Myxus petardi and Gobiomorphus australis. Gobiomorphus coxii, Potamalosa richmondia and Notesthes robusta displayed Sr : Ca patterns that indicated that these species may have more complex movements between marine and fresh water. Overall, these results provided quantitative data that supported the lifecycles previously hypothesised for most of the studied fish species. However, M. petardi, which was thought to be catadromous, displayed Sr : Ca variations that suggested an amphidromous lifecycle, at least for the specimens examined. These results also provided further evidence to demonstrate that otolith chemistry is a useful tool for studying the movement patterns of diadromous species and this technique will be especially valuable in identifying species that are most at risk from river regulation and barriers to migration. Show more