This week our foremost Australian Native fish expert Simon Kaminskas gives us the low down on the worlds biggest freshwater sport fish that is unique to Australia. Take it away Simon.
“Today, we are looking at Murray Cod. Murray Cod are a fish dear to the hearts of myself and many other anglers. Indeed, Murray Cod are not just a fish. They are one of the most unique and beautiful native Australian animals around, and until white man’s arrival, one of the most successful. They have evolved along with the Australian landscape and climate for a staggeringly long time - fossil records show that they evolved from their marine ancestors and into the freshwaters of the newly born Murray Darling System 60 million years ago.
Murray Cod are remarkable by any ecologist’s standards in how adaptable they are. They are found in a wide range of habitats, from the widest, slowest reaches of the lower Murray River to tiny rocky streams on the upper slopes of the Great Dividing Range. Murray Cod look like the groper-type fishes that it evolved from, with a big body, big mouth and wide paddle tail, and a beautiful mottled green colour that varies to suit the water they live in and helps make them invisible against the river bed as they rise up to eat unsuspecting prey.
They are the big boss fish, and they have real character. They are meant to out-compete all the other species of fish in the river and each other. They take the best snag or shelter in a stretch of river and thump anything that comes near. A fearsome predator, they will eat anything that will fit down their huge mouths. Murray Cod have been found with everything from shags, cormorants and ducks to 70cm water dragons (type of lizard) and turtles in their mouths. More regular food includes other fish, yabbies and Murray Crays. During the day, they are an ambush predator, lurking in a snag and flying out and hitting anything that swims past. With their big paddle tails, Murray Cod are truly fast from a standing start and over a short distance. This gives more than enough speed to catch the prey they want. At night, they will cruise around and deliberately hunt for things to chomp.
The thing that most people know about Murray Cod is their size. They are officially considered to be the 4th largest wholly freshwater fish in the world after three species of weird catfish found in the Amazon and in Europe. If you don’t count catfish as sport fish (most don’t), then the Murray Cod is the planets biggest freshwater sports fish, and whats more they respond to lures and fly with gusto. This is the reason why expert overseas anglers are amazed when they learn even a little about these huge predators.
Many fish ranging between 45 and 55 kilos have been reliably recorded over the years, while the largest was a staggering 113.5 kilogram fish caught by some bridge builders in the Barwon river in 1902. They regularly reach 15-20 kilos in weight. Murray Cod live for a long time too. One big old fellow of around 45kg, that was sadly killed by a speedboat, was found to be 47 years old. And it’s a fair bet that they live quite a bit longer than that.
When the Murray-Darling basin was settled in the 1830s and 1840s, the rivers and streams of the Murray-Darling were bursting with Murray Cod. Murray Cod were the dominant fish, and outnumbered other native fish by about 3 to 1. Early settlers wrote about how amazingly abundant Murray Cod were, and how they were found even in the smallest of streams.
Hundreds of thousands of tons of Murray Cod were taken every year by commercial fishermen with nets and by recreational fisherman. Black and white photos show fishermen with hundreds and hundreds of big dead Murray Cod, all caught in a single day. Old timers talk of how clear the rivers were, and how you could see the big cod swimming in the water. People today would have trouble imagining how common Murray Cod were then, and how different our rivers were then, flowing through uncleared forests and woodlands with crystal clear water.”
Amazing stuff Simon, next week ‘Simo’ looks why the worlds most amazing fresh water fish is in trouble, bad trouble.
Until then see you on the water.
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