Reproductive biology of the threatened golden galaxias Galaxias auratus Johnston and the influence of lake hydrology

Golden galaxias Galaxias auratus (31-235 mm fork length, LF) were collected monthly from littoral habitats in Lakes Crescent and Sorell, Tasmania, Australia, between July 2000 and December 2002. Spawning habitats were identified and monitored in both lakes, and surveyed in Lake Crescent. Trends in gonado-somatic indices and reproductive stages of development indicated that gonad development in both sexes begins in midsummer and peaks in late autumn to early winter. Males mature at smaller sizes (50% at 52 mm LF) than females (50% at 76 mm LF), larger individuals are predominately females (95% of fish ≥138 mm LF), and overall male to female ratios are female biased (c. 1:2). Spawning occurs late autumn to early spring (water temperatures = 1.4-9.7°C) with peaks in spawning activity in winter (mean water temperatures