Environmental alterations in southeast Queensland endanger the Australian lungfish, Neoceratodus Forsteri (Osteichthyes: Dipnoi)

Abstract

Water impoundments across rivers in southeast Queensland have profound effects on the fish that live there, especially the lungfish that inhabit these reservoirs, most of which have no operating fish transfer devices that are suitable for lungfish, or no fishways at all, such as Enoggera Reservoir, Lakes Wivenhoe and Somerset in the Brisbane River system and Lake Samsonvale in the Pine River system. A population of the threatened Australian lungfish, Neoceratodus forsteri, lived in Enoggera Reservoir since they were first introduced there in 1896, but may now be extinct. Lungfish are endemic to the Brisbane River, and lungfish live in relatively unchanged reaches of this catchment. However, adult lungfish living in Lake Wivenhoe, and in Lake Samsonvale, have been trapped in these reservoirs since 1984 and 1976 respectively, and recruitment has ceased, perhaps because the population of fish in these reservoirs is ageing, or because the adults have poor food supplies and cannot lay viable eggs. Analysis of the gut contents and the dental structures of lungfish involved in the Lake Samsonvale and Lake Wivenhoe fish kills of 2009 and comparison with material collected between 1981 and 1990 from the Brisbane River below Lake Wivenhoe, and with specimens collected by electrofishing in Enoggera Reservoir in 1981, indicates that the adults in the fish kills of 2009 were not old, but had eaten nothing for a long time.