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Before the barrages, in the townships around the Lower Lakes there used to be a thriving mulloway fishery. Back in the 1930’s, fishing was the sole livelihood for approximately 100 men and their families around the Lower Lakes. Their main source of income, the mulloway, or as they are called in South Australia “butterfish”.
Mulloway travel between the ocean and freshwater as part of their lifecycle. They adults spawn in the marine waters then the juvenile mulloway grow up in the estuarine waters for about 3-4 years. A mature old mulloway can be 25 years old and weigh 40kg, but currently the sizes caught today are much smaller.
It is essential that mulloway have access to and from their estuary. And they don’t use fish ladders.
Prior to the barrages in 1938/1939, almost 600 tons of mulloway were caught in the Lower Lakes and Coorong. Reports from the period are sketchy, but the fishermen were routinely pulling in several hundred tons of Mulloway each year and sending them to Adelaide and Melbourne markets.
There are also reports of mulloway in the Finniss River pre-barrages, over 10km inland. In 1930 one ton of mulloway were caught by commercial fishermen at the mouth of the Finniss river.
Since the closing of the barrages in 1940, the mulloway catch has plummeted. In fact, the late Director of Fisheries A.M.. Olsen writes in his 1991 report, that while other fisheries may have been affected and survived, the “mulloway fishery was decimated by the barrages”.
In 2008/2009, the annual commercial catch of mulloway in the Lakes and Coorong Fishery was only 30 tonnes. For comparison the now freshwater Lakes commercial catch of European carp in 2008/2009 was 792 tonnes worth $863,000. Many of the Lower Lakes fishermen now catch carp, instead of mulloway, to earn a living.
Freshwater flows attract mature mulloway from the sea back to the estuary. A lack of freshwater flows and overfishing has been blamed for a diminished mulloway catch. However, when the barrages were closed in 1940, not only did they create a barrier for the mulloway, the barrages effectively took away 89% of the estuarine habitat used by juveniles.
How much blame for the demise of the mulloway goes to a lack of freshwater flows, and how much should go to habitat destruction?
Can we restore the estuary and bring back the Mulloway?
Sources:
"BARRAGES WOULD KILL BUTTERFISH". (1933, October 25).The Advertiser (Adelaide, SA : 1931 - 1954), p. 22. Retrieved August 16, 2011,
Economic Indicators for the Lakes and Coorong Fishery 2008/09
Report for PIRSA by Econsearch, pp. 6-7, 16 June 2010
Preliminary Economic Indicators for the Lakes and Coorong Fishery 2009/2010
Econsearch, January 2011
Olsen, A.M. 1991 The Coorong - A Multi-species Fishery. Part 1 – History and Development
Mulloway Fishery, Fishery Stock Assessment Report for PIRSA Fisheries and Aquaculture, Sept 2011
Historical photos pre-barrages of 91 pound Mulloway at Milang, c.1938
Historical photos of Mulloway catch at Goolwa, c 1921
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