Status of non-native freshwater fishes in tropical northern Queensland, including establishment success, rates of spread, range and introduction pathways

Abstract

At least 20 non-native fishes have been reported from northern Queensland fresh waters, a 75% increase since 1994. Eleven of these species have established breeding populations and some are locally abundant and highly invasive, such as the tilapiine cichlids (Oreochromis mossambicus and Tilapia mariae) and the poeciliids (Gambusia holbrooki and Poecilia reticulata). Besides the continued introduction of non-native species, of great concern is the further spread of the tilapias, especially Oreochromis mossambicus and its hybrid form, and of another invasive, the three-spot gourami, Trichopterus trichogaster. Initial introductions are most probably releases of unwanted aquarium fish directly into open waters, or indirectly from ornamental ponds by flood waters. While natural dispersal is occurring, most of the range expansion of the tilapiine cichlids, particularly into impoundments in flood-prone areas, has been as a result of human translocation, and possibly the use of live bait by anglers.