Rewriting Murray History for a Fish

With the many problems besetting the Murray Darling Basin, the last thing a group of scientists was expecting to find was a new species of fish in the lower lakes.

Initially, the group from Adelaide University thought the small greenish perch was new to science, but on further examination realised it was the Yarra Pygmy Perch (Edelia obscura).

In fact, the species no longer occurs in the Yarra River in Victoria.  It was thought to be extinct there due to all the development associated with what is now the city of Melbourne.

The scientists who discovered the rare species in 2001 were quick to point out that the find had implications for the management of the Murray River.

The species prefers freshwater and the only way to ensure the lower lakes stays fresh is to keep the barrages in place on the Murray's mouth at Lake Alexandrina and Lake Albert below Wellington, South Australia.

The barrages were built 80 years ago to stop salt water from flowing in and freshwater from flowing out through the mouth of the river.

Because the barrages have changed the ecology of the region, I thought many of the Adelaide-based scientists would be pleased to see them go.  But local ecologists tell me they want the barrages to stay, including to protect the habitat of the Yarra Pygmy Perch.

European perceptions of the Murray River have changed with time.  Charles Sturt described the mouth of the Murray River as being at Wellington, upstream of the Lakes.  But try telling that to a South Australian now and they assume you are playing politics and trying to deprive the Lakes of a Murray water allocation.

Many South Australians also like to pretend that once the water from the Snowy Mountains flowed mostly to South Australia, but in reality before the dams and weirs, it would have gushed from the mountains and then spread across the central Murray Valley, regularly flooding what is now the rice growing region of Deniliquin.

I suspect the Yarra Pygmy Perch existed in Lake Alexandrina long before European settlement -- we just never noticed it.  Furthermore, I suspect that the removal of the barrages would not result in its extinction -- it might just be pushed further upstream back towards Victoria.

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