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Rabbits of the river: Trout are not native to Australia

The World’s Largest Trout in Adaminaby pays homage to an introduced pest that harms native fish. Halans/flickr

Yesterday’s announcement of the removal of trout from a small creek in the Alpine National Park to protect a critically endangered native fish highlights the problem that is trout.

Trout have been so successfully and so pervasively introduced into Australian freshwater systems that most people now think that they are native. The truth is that trout have caused the extinction or demise of many freshwater fish and invertebrate species, including some excellent angling fish such as the Murray cod, Macquarie perch and trout cod.

The introduction of trout to Australia was supported by Acclimatisation Societies which supervised the hatching and release of introduced trout without any consideration of its impact on native fauna.

This does not surprise us because we know that these organisations deliberately introduced thistles, sparrows and rabbits, all of which are well known pests in an Australian context.

The surprising thing is that trout have evaded the pest label, and despite abundant evidence that they are causing the extinction of native fauna, their continued existence in Australian rivers is supported by government agencies that release millions of trout fry every year.

These same agencies are responsible for protecting the native species impacted by trout, and ironically breed and release trout’s victims at the same time. In 2012, Victorian Fisheries hatched and released Murray cod, golden perch, trout cod, silver perch, Australian bass and Macquarie perch, all of which are native fish struggling to compete with trout. At the same time they released brown trout and rainbow trout despite the fact that many trout populations are known to be self – sustaining (in other words, not at risk of extinction). To be fair, Victorian Fisheries now only releases troutinto lakes or impoundments, but the movement of these populations into nearby rivers is virtually guaranteed.

Trout have been removed from other small rivers and creeks in the past to protect the barred galaxias and the spotted tree frog. The responsible agencies are aware that trout are a serious threatening process, and yet they are unlikely to ever remove trout from a large river. This is because recreational fishers have come to believe that trout fishing is something which every Australian has a right to. Worse, many fishers think this is because trout are a natural part of the Australian environment and therefore deserving of our protection.

Obviously, trout fishing is an important part of the tourism industry and many rivers are so well stocked with trout that there is no point in trying to remove them. On the other hand, few Australians realise that we enjoy trout fishing at the cost of excellent native angling experiences.

Macquarie perch and trout cod (formerly known as blue-nose cod in Victoria) were excellent angling species before they became endangered. Murray cod are still highly prized where populations are not too vulnerable to be fished, but they no longer grow to the great sizes of the past.

People who fished the Murray River used to be called “whalers” because they came back with monster fish as large as themselves. Current regulations require anglers to throw fish back if they are above a certain size, so the thrill of fishing for something that could be larger than yourself is no longer available.

This is not due to trout alone, of course. River regulation, pollution and habitat alteration all play a role in declines of our native fish. But the reverence with which trout are held among fishers obviously plays a role.

The construction of a barrier to prevent trout from moving into a small stream and the removal of 700 trout by electro-fishing is an important and laudable step towards the protection of one species of upland native Australian fish. The Shaw galaxias is a critically endangered species that would not have survived without this intervention.

But let it also remind us that trout are threatening native fish in rivers, impoundments and lakes, and too few people are concerned because they think that trout belong here.

Unfortunately, trout are actually worse than rabbits, because they are both carnivorous and voracious. As a fisher said in 1905 in the Sydney Morning Herald: “Trout will eat anything but the log fences hereabout. They have cleared out the bream, the cod and the carp, but we will not mind that if they stay themselves.”

Some of us do mind.