Freshwater Fisheries

One fish stands out among the species that inhabit Australia's inland rivers. The Murray Cod, which can grow to 180 centimetres and exceed 100 kilograms, was once abundant in the waterways of the Murray Darling Basin and was the dominant fish for both indigenous people and colonists alike.

Not surprisingly the Murray Cod was one of the most active and important Victorian commercial fisheries. Frederick McCoy was perplexed that the species did not occur in rivers flowing south from the Great Dividing Range, but as a man of action he sought to put right the situation.

Both McCoy and his counterpart at the Botanic Gardens, Ferdinand Von Mueller, were among the distinguished Victorian scientists of the day who belonged to the Acclimatisation Society of Victoria.

The Society sought to 'redress nature's imbalance' via selective introduction of various animals and plants, with rabbits, foxes and blackberries among the more notorious local examples of this misguided movement. Less known is the attempt to acclimatise a native Australian fish.

As the largest and potentially most lucrative local candidate, the Murray Cod was promptly introduced into rivers south of the Great Dividing Range. McCoy subsequently reported the species was established but 'does not thrive in the Yarra River, but through its voracity diminished the numbers of native fish in the river,' such as the 'Blackfish and Yarra Herring', particularly in the river's lower reaches.

In retrospect, it is likely that environmental degradation and pollution had more significant impact on native fish, rather than predation by Murray Cod.