4 Natural flows drive the boom and bust’ ecology of fish in Cooper Creek 49 Although their spawning strategies vary, most native species in Cooper Creek benefit from rising channel flows and floods by moving into backwater habitats, flooded channels and floodplains to feed and grow in shallow, food-rich, warm-water habitats (Balcombe et al. 2007). Fish use backwaters and flooded areas as larvae, juveniles and adults. All native species other than Australian smelt and Cooper Creek catfish have been caught on the floodplain as adults, and nine species have been collected in the juvenile life stage. Sampling in floodplain habitats has also yielded the late stage larvae of six native species (bony bream, yellowbelly, Hyrtl’s tandan, silver tandan, smelt and spangled perch). The Cooper Creek catfish may be the only native species to spend its entire life history within waterholes and channels. Juveniles and mature individuals of the alien mosquitofish have also been recorded from floodplains however, goldfish captures have been confined to waterholes. Access to floodplains, feeding on diverse food items and high growth rates allow most Cooper Creek fish to build up large populations and significant biomass (Fig. 4.2). During the 2004 summer flood in Cooper Creek, shallow floodplain areas near Windorah supported high fish biomass in the range of 21–240 kg/ha. These biomass figures are comparable to production from important floodplain fisheries in Bangladesh (50–400 kg/ha), the Mekong (138–175 kg/ha) and the Amazon (24 kg/ha) (Balcombe et al. 2007). The global literature Fig. 4.3. In boom phases, the high productivity in waterholes and on floodplains provides opportunities for fish species such as these spangled perch, Cooper Creek tandan, Lake Eyre golden perch, Barcoo grunter, silver tandan, Hyrtl’s tandan to build up their populations. Fish catches were identified to species, counted, measured and weighed. Turtles and most fish were returned to the water alive (photo, S. Balcombe).
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