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Reproductive Cycle of Golden Galaxias (Galaxias auratus)

Scott Hardie

Inland Fisheries Service, PO Box 288, Moonah, Tasmania 7009, Australia
University of Tasmania, School of Zoology, GPO Box 252-05, Hobart, Tasmania 7001, Australia
Email: Scott.Hardie@ifs.tas.gov.au

The golden galaxias (Galaxias auratus) is endemic to the interconnecting lakes Crescent and Sorell and their associated streams and wetlands on the south-eastern corner of the Tasmanian Central Plateau, in south-eastern Australia. G. auratus is one of the largest Galaxiidae species (growing to 240 mm) and is a typical example of an endemic Tasmanian galaxiid species, being confined to a relatively small geographical region and only a few water bodies. The evolution of the non-diadromous G. auratus is thought to have involved the land-locking and subsequent speciation of an ancestral version of the generally diadromous spotted galaxias (G. truttaceus). Work conducted between 2000-2003 examined the current status and ecology of G. auratus populations in lakes Crescent and Sorell and the Clyde River catchment. Prior to this work the ecology of G. auratus had not been formally investigated. The reproductive cycle of G. auratus was found to have several interesting characteristics that resemble the usual patterns of both diadromous and non-diadromous Galaxiidae species. G. auratus was found to have inter-population variability and tended to spawn in late autumn-early winter similar to diadromous species, however larval hatching and recruitment occurred in late winter – early summer similar to other non-diadromous species. The relatively small egg size (1.5 mm diameter) and high fecundity (up to 15, 000 eggs) is also similar to diadromous species. The evolutionary history of G. auratus appears to be reflected in the reproductive cycle of this non-diadromous species.