People love invasive species

What gives an animal the right to exist?

We often protect and value animals because they are native, they are part of the system, and they should be there because they have always been there.

Dingoes are considered native, but they haven’t been in Australia for very long (one estimate is less than 5000 years). What makes them different from domestic dogs that came to Australia with Europeans? Feral dogs and dingoes are genetically very similar, and they have interbred and hybridised with one another. This can make it difficult to decide what is considered a dingo.  Do you think that the small percent of genetic difference between a wild dog and a dingo is justification to protect one and mercilessly hunt the other?

It can be difficult to visually distinguish “pure” dingoes from hybrids. Photo by Andy McLemore via Flikr

Invasive fish

It is clear that “nativeness” is tricky. So, maybe we should think about the right to exist from another angle, using two non-native fish that Australians view very differently – carp and trout.

Both are recently imported species (within the last 150 years), both inhabit our freshwater systems, and both have adverse effects on the ecosystem. However, Australians love trout and hate carp.

We breed and introduce millions of trout into our rivers annually.  We divert taxpayers’ money to make our rivers more suitable for them and erect huge monuments to this revered invasive fish.

The Big Trout in Adaminaby, New South Wales. Photo by Robert Merkel via Wikimedia Commons


On the other hand, our government recently pledged $15 million to eradicate carp from our waters. The aim is to infect these “mud-sucking bottom feeders” with herpes. We haul them out the water and leave them to die on the bank or grind them up to be turned into fertiliser.

Why do we accept one non-native and not the other? Are carp more damaging than trout?

The answer is probably not.

In fact, it may be the other way around. Wherever trout are introduced, they have clearly, repeatedly been shown to directly eliminate many small, native fish. They compete for prime habitat and food, and prey upon many of our native fishes.

Carp too affect our waterways, mostly by dirtying the water and affect natural processes. However, their impacts on native species are less direct and the evidence of the impacts is a little muddy, especially in Australia.

Is environmental impact a good way to decide which alien species to accept? Cows are a non-native species and they are highly damaging to the environment, the land and the atmosphere. Despite this, cattle farming is an accepted, widespread industry and arguably a part of Australian settler identity.

Curious cows observe fish sampling in a degraded creek – their impacts on the bank and stream itself are clear. Photo by SiYing Chan used with permission.

It’s all about perception.
Maybe it’s because trout and cows have a “use”, but carp are just pests.

In parts of Europe where they are not native, carp are highly sought-after sport fish. People name individual carp (Stella and Dave are my favourites), they come from miles around to try and catch these fish and they hold funerals for them when they die. They are a prized fish for eating.

No such attitudes exist in Australia. However, when asked about why they hate carp, most people aren’t that sure, or they cite the environmental impacts of these fish – but what about the impacts of trout? Or cows? It appears that most Australian’s just don’t like carp.

Upfront about our prejudice

Who is to say that we can’t like one non-native animal and not the other? I guess that’s what we as a society get to say. Countries like some sports and not others, why not animals?

We should at least be upfront about this, because it can be problematic when dogma about an animal gets in the way of recognising and mitigating against its impacts. Just look at the comments of any online article that says anything remotely bad about trout and you’ll see what I mean.

Discussions online about the impacts of trout get rather heated.


Trout have real, damaging impacts on our environment. They heavily predate upon the small native fish species, yet they aren’t even listed as an invasive species in most states! We are allowed to like fishing for trout, but if they aren’t allowed to be acknowledged as damaging, how can we effectively manage their impacts? We can keep trout, but we need to be smart about it. We can’t be smart about it if we don’t even recognise that we need to be.

One Response to “People love invasive species”

  1. Teresa Hassett says:

    Such a frustrating issue. Invasive species can have severe negative effects on ecosystems, but given their association with humans, they are viewed differently. This is where social values come in and interfere. These values still need to be considered during management efforts though. For example, feral cats are a huge issue in Australia, but the best solution would be to remove all cats, or only only cats that are kept indoors at all times. This definitely wouldn’t go down well. It’s all about what is valued more – human interest or the environment. Unfortunately it reaches a point when the environment is so damaged that it negatively impacts humans too.