Fish Future’s Finnbar Lee, Nixi Boddy and Prof Angus McIntosh explore how research on six Southern Hemisphere fish species has evolved over the past 50 years.
Amphidromy is a unique life-cycle strategy in some fish species, where they spawn in freshwater or brackish water, and their larvae then move to the sea. After developing in the ocean, the juveniles return to freshwater to feed and grow before maturing and spawning. Six species from the Southern Hemisphere genus Galaxias (G. truttaceus, G. fasciatus, G. argenteus, G. postvectis, G. brevipinnis, G. maculatus) are important for recreation, culture, and economics, as juveniles are harvested. However, concerns about their declining populations have grown due to a lack of key demographic data.
In this review, we analysed 295 research studies on these species over the last 50 years to identify how research focus has changed and pinpoint gaps in knowledge. We found that 40% of studies focused on small areas (less than 10 km) and 87% were short-term (under 2 years), which doesn’t match the wide distribution and long lifespan of these species. Research on climate change, disturbances, and the marine phase of these species is particularly limited. We also found that quantitative models have been underused, but could help answer important questions. To properly manage these species, a better understanding of their population dynamics over time and space is needed, and key research gaps must be filled.