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Australian Environmental Issues

A true-blue battler

Box jellyfish
How to avoid the stings and what to do if stung

So you wrestle crocs...

Unfairly judged in killing off the thylacine?

The wise little gnomes of Australia

Victors of the great Emu war

Shaping everything from how Australians speak to how they salute

Funnel Web spider
Yyou'll never leave your ugg boots outside

Most herbivores don't grow a spine until they are the size of an elephant. Not so the roo.

Kill less people than cows

Shark attack Australia
How to ensure you don't go by the name of Bob

Tasmanian Devil
The solution to mainland extinctions?

Tasmanian Tiger
A sad tale

Keg of muscle

The mainland's largest marsupial carnevore

Mythical creatures
Yowies and dropbears; some say they are myths but those who are not afraid to talk have shared their stories






cdead carp

Carp and Trout

Why carp are hated but trout loved

Trout and carp are two introduced species that have fared vastly differently in Australia’s hot climates and in the court of public opinion. Whereas trout need are continually re-stocked to keep the anglers happy, carp were introduced to Australia in the 1860s and were so good at surviving that they now constitute around 80% of the fish biomass in south east river systems (1). Although the sheer number of carp offers great eating and fishing opportunities, it is fair to say that they evoke emotions that are somewhat akin to anal warts.

Such is the dislike of the fish, laws exist that prohibit the return live carp to the water ways. Although the laws have failed to eliminate carp and would make almost no difference to carp numbers, it could be argued that the laws exist more for a symbolic purpose. Specifically, they aim to communicate that carp are a pest to be disliked and should be treated accordingly. Some anglers take the symbolism further by torturing them or smashing their bodies before throwing into the bush. Some even defy the law by cutting out their eyes and cutting off their fins but then throwing them back alive where they see the carp swim in circles or into banks before eventually dying. Admittedly, while the torture is outside the literal wording of the law, it is within the spirit of it.

There are a number of explanations for why carp evoke so many negative emotions that trout do not. The aesthetic explanation is that the carp muddy up the water as part of their feeding technique and this looks a bit unappealing. Admittedly, many rivers and lakes are muddy regardless, especially after floods. Nevertheless, it can't be disputed that the carp deny the nature lover the view that would look more appealing if carp weren’t in it. Although killing the carp in these water bodies might not be justifiable on environmental grounds, it could be justified on Instagram grounds. That said, the smell of dead carp thrown to the side of the banks by fisherman is pretty horrendous and muddy water might be preferable by comparison.

Darling River in Flood

Carp are often blamed for making water muddy. Although it is true, muddy is the default state for many Australian bodies of water.

A cultural explanation for the hatred is that carp are often found in polluted water ways and suffer from the association. (This is a marked contrast to trout that prefer the crystal clear streams associated with cleanness.) The psychology can perhaps be compared to the negative emotions surrounding India’s Dalits (untouchables). In past generations, the Dalits performed dirty activities such as cleaning, fishing, leatherwork and sweeping which caused an unclean stereotype to be applied to them. In the same way, seeing carp swim among plastic bags and polluted stormwater creeks makes people think of carp as a dirty fish.

Carp in rubbish water

Carp are often found in polluted waterways and perhaps suffer form the association. Instead of picking up the rubbish, people express their emotional dislike of rubbish by killing the carp.

The sporting explanation is that carp are ranked at the bottom of the fishing hierarchy. The Australian government publication, National Carp Control Plan (1), defines them as a “trash fish” that get in the way of catching natives. This is not really true because carp need to be targeted to be caught. Natives are best caught with lures while carp go for corn or dough. A yabby used to fish for cod might be taken by a carp but it is unlikely. Nevertheless, defining carp as a trash fish is probably correct as because buying a can of corn from the supermarket, pulling up a chair, casting a line and waiting is a trash form of fishing. Such fishing doesn’t lend itself to the feats of endurance that are required to trudge up and down the streams in search of trout or cod using a lure or fly. Nor does it lend it campfire discussions involving plotting strategies to outwit an animal with a brain less than the size of a pea. Finally, it doesn’t justify buying the expensive polaroid sunglasses, the box with a thousand different types of flies, the wading tights and the perfectly waited rod that is the envy of all. No, carp fishing is cheap, easy and not story worthy. It is akin to fishing in a fish farm. Admittedly, carp can be hooked with a fly and thus give the Australian fly fisherman the chance to experience something larger than 10 inches on the line; however, carp prefer still water while the pinnacle of fly fishing has flowing water that tests the fisherman’s control of line.


Fishing is a sport and good sports require exercise and strategy to ponder and outwit one's foe. Buying a can of corn and sitting on a chair ranks poorly in the sporting sense.

The culinary explanation is that carp eats mud which gives it a muddy taste only liked by Asians. Such claims reflect the way that taste is wrapped up with a psychology of cultural perception. In the same way, lobsters in 18th century America were defined as “cockroaches of the sea” because of their scavenging nature. They were given to slaves and convicts to eat or just used as fertiliser. It was only when lobster numbers declined and they were served in expensive restaurants that their image as a delicacy was forged. The claim of carp's muddy taste is misplaced.  If carp are killed with minimal stress and a vein on the shoulder quickly removed, they have a flavour that is quite palatable and not muddy at all. Due to their abundance, it is unlikely they will be seen as a delicacy any time soon. Nevertheless, with a bit of care in preparation and the ability to supress the negative messages of popular culture, carp can make a tasty meal.

Even though there are strong voices to eradicate carp, there is little whole ecosystem research as to they have become dominant in the waters ways and even if they really are much of a problem. In popular culture, there are suggestions that carp are an ecological disaster that are pushing other fish to extinction but this is debateable. Specifically, carp are the bottom feeders of the fish world and largely survive on insects in mud. They don’t eat other fish and would even struggle to eat the eggs of fish like cod that usually have the father protecting them. Instead of eating other fish, carp are the ones being eaten. Small carp are an easy meal for cod, yellow belly, red fin and trout. Additionally, cormorants and turtles munch them down. To say it’s their fault other fish are low in numbers is a bit like saying it’s the cow’s fault that tigers or lions are declining.

As for why they have become so dominant, the most likely reason for their success is that they have an ecological niche in artificial water bodies such as dams for stock, dammed rivers and storm water creeks which are depleted of oxygen and reach high temperatures. Native fish wont breed in the water ways if they are not connected to running flowing water and/or will die at temperatures lower than will kill carp. This niche alongside humans extends into the semi-modified waterways that suffer massive kills black water, blue-green algae and bushfires. (These kills may or may not be related to human activity.)

Blackwater Murray

Native fish killed by red gums in a 2011 blackwater event. Floods wash eucalypt leaves that build up over the years into waterways. When they decay, they suck oxygen out of the water.

Native fish killed by blue-green algae in 2018. Increased agriculture along water courses increases nutrient flow into the water that leads to algae blooms. When the algae dies, it sucks oxygen out of the water. This is particularly severe in Australia as native plants are poor at biofiltration. The problem has been compounded by the removal of willows that are very good at biofiltration.

Not only does the carp's superior ability to survive hot temperature and low oxygen allow them to survive in the semi-artificial waterways where other fish might die, but their ability to survive in the human constructed water ways allow huge fish to recolonise the semi-artificial waterways when all the native fish are tiny. In regards to dominating biomass, obviously if a 20kg carp escapes a dam or stormwater creek to a water body that has recently suffered a fish kill, any sampling of weight will be biased in its favour. There will also be a bias for decades to come as it produces thousands of eggs each year while others get up to breeding size.

An additional reason for why carp dominate biomass is that humans have made conditions more difficult for native fish by damming streams causing migration to stifled, regulating stream flow to stop flooding the triggers breeding, pulling out snags used for spawning sites, using fertilises that contribute to algae blooms and using more water for agriculture that would otherwise be available for fish. In other words, carp are not out competing native fish but native fish are just declining due to human activity whereas carp are benefitting from human activity. In a way, carp are victims of a perverse form of survivor blaming. Humans just want them to die like all the other fish.

As of 2019, the CSIRO has imported a species-specific virus (cyprinid herpesvirus 3) which it hopes will kill up to 70 per cent of the carp. Releasing the virus will probably give the CSIRO the same kind of emotional satisfaction felt by some fisherman who torture carp but otherwise fail to remove them from the ecosystem. The 30 per cent that survive will pass their immunity onto their offspring. As for the effect on other species, the virus itself is unlikely to mutate or jump but the water birds, predator fish and turtles that eat carp will have to find alternative prey or just die. Meanwhile, the virus will do nothing to remove rubbish from waterways, decrease fish deaths from blackwater and algae blooms, create spawning sites for native fish, facilitate fish migration in dammed streams or increase the amount of water flowing into the river system. Instead of carp comprising up to 80 % of the fish biomass in many systems, there just won’t be any fish at all...then the carp will return. It’s a plan that seems bout as desirable as contracting anal warts.

1) http://www.carp.gov.au/en/the-carp-problem

Invasive ferals


Carp and Trout
A tale of two ferals

New hope for Cane Toads
The many unknown predators of the toad

A fence almost 2,000 km long to keep rabbits out of WA? Sounds like a great idea! If it doesn't work, we'll build another one!

The Willow
How a change in its status from asset to weed led to fish kills with blackwater and blue-green algae outbreaks

To bait dingos?
Should the health of the ecosystem be considered or just the kennel club registration?

Koala control
What to do about the "koala plague" on Kangaroo Island

Apex predator in Australia. Confined to urban areas in America.

Environmental values

Environmental problems
How money and ideology shapes environmental "science."

Australia's Stockholm Syndrome with gum trees.

The Kangaroo industry
Should we eat skippy?

Climate change in Australia
Australia was once covered in rainforest. Could it be again?

The dark side of sustainable environmental policies

Native pets
Why no pet wombats?




Australian environmental science is defined by an ideology that is not unlike a prison warden. There, the scientists are not seeing themselves as part of the ecosystem, but as masters over it; protecting the rights of the species that they say have rights and killing those that they say do not…but inevitably killing both.

"It was always seen as desirable to remove or cull the introduced species. We also need to ask whether it was possible to do so, how it should be done, whether it could have unintended consequences and what it would cost? I don't think anyone really asked those questions." Physicist John Reid - 2012