Darling River fishkill as floodplain drains

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Darling River fishkill as floodplain drains
It is estimated that millions of fish died in the Darling River around Brewarrina as deoxygenated water drained from upstream floodplains during March. The main species affected included common carp and bony bream, with spangled perch, golden perch, the common yabby and fresh water shrimp also present.
NSW DPI staff, using the NSW Fish Kill Protocol, inspected the Darling, Bogan and Macquarie Rivers. As well as the significant numbers of dead and dying fish, millions of fish were also observed schooling below the Brewarrina Weir trying to move upstream and possibly being attracted to the better water quality conditions due to mixing of water below the weir.
Laboratory testing confirmed what the on‐site tests suggested: the fish died of asphyxiation resulting from extremely low dissolved oxygen (DO) levels in the water.
Low DO events are a natural part of the ecology of lowland river systems following the rapid breakdown of organic matter on the floodplain. The unprecedented weather conditions of prolonged drought followed by rain and heavy flooding have contributed to the severity of the current event.

For more information contact Sarah Fairfull (NSW DPI) on 02 6626 1369


Source: NSW DPI
Photo: David Ward - A white ‘tide’ line of dead fish along the bank of the Barwon River.