Mulloway in the Lower Lakes and Coorong


The Mulloway Fishery 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 livlihood 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 fresh water 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 90 lbs, 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 butterfish (mulloway) were caught in the Lower Lakes and Coorong. That is nearly twice the usual previous annual catch. 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 reports of Mulloway in the Finniss River pre-barrages. 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 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 over-fishing 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 Mulloway's demise 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,

"NETS AS EVIDENCE, Part 3"

Economic Indicators for the Lakes and Coorong Fishery 2008/09
Report for PIRSA by Econsearch, pp. 6-7, 16 June 2010 

Econsearch, January 2011

Olsen, A.M. 1991 The Coorong - A Multi-species Fishery. Part 1 – History and Development