Lack of oxygen kills fish
Posted Wed Mar 31, 2010 9:49am AEDT
MAP: Pinjarra 6208
Authorities are blaming last week's storm for the deaths of about 1,000 fish near Pinjarra, south of Perth.
The bream were found along the Murray River near the Dandalup River mouth.
The Department of Water says there was a lack of oxygen in the water after fresh water was flushed into the river by the storm.
The Department's Leon Brouwer says the fish would have suffocated as a result.
"The rainfall event causes a lot of organic matter and other things to flow down through the water column, so the oxygen demand in the water column is very high and it essentially just strips out what available oxygen there is in the water column in a very quick time.
"Some species have been seen, like mullet and herring, swimming upstream from the areas we located the fish kill but others that do get caught out in those pockets where there's no oxygen can suffocate."
Fish kills have also been reported in the Swan and Canning rivers over the past week.