Spatiotemporal patterns of research on Southern Hemisphere amphidromous galaxiids: A semi–quantitative review

Abstract

Amphidromy is a distinctive life‐history strategy of some fish species that involves spawning in fresh or brackish water followed by dispersal to sea by newly hatched larvae, where they develop for a short period. Individuals then return to freshwater as juveniles, where they feed and grow, before maturing and spawning. Six amphidromous species from the Southern Hemisphere genus Galaxias (G. truttaceus, G. fasciatus, G. argenteus, G. postvectis, G. brevipinnis, G. maculatus) are recreationally, culturally, and economically important as the juveniles are harvested. Due to ongoing population declines and a lack of critical demographic information, there is growing concern about the management of the species. Here, we used semi‐quantitative review, culturomics, and bibliometric tools to analyse peer‐reviewed research conducted on the six amphidromous species of Galaxias to: (i) understand how spatiotemporal patterns of research have shifted over the last five decades, and (ii) identify critical research gaps. Forty percent of studies (n = 295) covered a spatial extent of 10 km or less and 87% of studies lasted less than 2 years – studies were largely small and short relative to the species' ranges and their longevity. Additionally, we found important research gaps; for example, studies on the effects of climate change and the associated effects of disturbance, and the marine phase are scarce in the peer‐reviewed literature. Finally, we suggest that quantitative models have been underutilized as tools for studying amphidromous galaxiids and should be embraced to answer questions not readily addressed with field and laboratory‐based techniques. If these species are to be effectively managed, their population dynamics across spatiotemporal scales must be understood and critical and long‐standing gaps in research knowledge addressed.