Migration to freshwater increases growth rates in a facultatively catadromous tropical fish

• Published in: Oecologia 2019-10, Vol.191 (2), p.253-260
• Main Authors: Roberts, Brien H., Morrongiello, John R., King, Alison J., Morgan, David L., Saunders, Thor M., Woodhead, Jon, Crook, David A.
• Format: Article
• Language: English
• Subjects: Aquatic crustaceans; Aquatic habitats; Aquatic organisms; Barramundi; Biomedical and Life Sciences; Brackishwater environment; Breeding success; Catadromous fishes; Crustaceans; Diadromous fishes; Diadromous migrations; Diadromy; Ecology; Estuaries; Estuarine environments; Fish reproduction; Fitness; Fresh water; Freshwater; Freshwater environments; Growth rate; HIGHLIGHTED STUDENT RESEARCH; Hydrology/Water Resources; Hypotheses; Inland water environment; Life history; Life prediction; Life Sciences; Marine fishes; Marine molluscs; Migration; Migrations; Mollusks; Organic chemistry; Plant Sciences; Primary production; Productivity; Reproduction; Reproductive fitness; River discharge; River flow; Rivers; Shellfish; Statistics; Tropical climate; Tropical fish; Tropical fishes
• ISSN: 0029-8549; 1432-1939
• DOI: 10.1007/s00442-019-04460-7

Diadromy is a form of migration where aquatic organisms undergo regular movements between fresh and marine waters for the purposes of feeding and reproduction. Despite having arisen in independent lineages of fish, gastropod molluscs and crustaceans, the evolutionary drivers of diadromous migration remain contentious. We test a key aspect of the ‘productivity hypothesis’, which proposes that diadromy arises in response to primary productivity differentials between marine and freshwater habitats. Otolith chemistry and biochronology data are analysed in a facultatively catadromous tropical fish (barramundi, Lates calcarifer) to determine the effect of freshwater residence on growth rates. Individuals that accessed freshwater grew ~ 25% faster on average than estuarine residents in the year following migration, suggesting that catadromy provides a potential fitness advantage over non-catadromous (marine/estuarine) life histories, as predicted by the productivity hypothesis. Although diadromous barramundi exhibited faster growth than non-diadromous fish, we suggest that the relative reproductive success of diadromous and non-diadromous contingents is likely to be strongly influenced by local environmental variability such as temporal differences in river discharge, and that this may facilitate the persistence of diverse life history strategies within populations.