A biological basis for the Tasmanian freshwater eel fishery

This thesis reports a five year investigation into various aspects of the biology of the freshwater eels Anguilla australis australis and Anguilla reinhardtii in Tasmania, from the tine of first entry of glass-eels into fresh water to the returning migration of adult eels to the sea. The invasion of fresh water by glass-eels of both species was studied in streams on the east coast of Tasmania. A. reinhardtii glass-eels were found to enter fresh water mainly during February, March and April whereas A. a. australis glass-eels exhibited a more extensive influx from March through to November. For both species the stage of pigmentation of glass-eels was found to advance as the season progressed and length, weight and condition showed an initial decline with advancing pigmentation. The otoliths of invading glass-eels of both species appeared similar with a single summer growth ring indicating a larval life of between 12 and 18 months.