RE: One great idea to follow another. Nothing could possibly go wrong.
It is only when people become aware of what is happening that we might affect change. Poisoning a system deliberately, for any reason, is immoral and ILLEGAL. What scope is there for taking them to court for environmental destruction? It affects not only the fish, but the birds, mammals that drink from the waterways, insects, invertebrates. plants surrounding the waterways and, in short, the whole ecosystem surrounding the poisoned area. This in turn has flow on effects as the food sources for many animals is reduced. It has to be stopped.
And, surprise, the only benefits are felt by the multinational corporations flogging off their poisons.
If you or I were to dump poison into a river system, we would be in court before the container was emptied. Yet these people seem to think they can do it with impunity. And because people are so ignorant, they can.
The poison they're using, rotenone, is more along the lines of an insecticide which kills fish, but is short lived. So thankfully, most other wildlife will survive it as long as they don't breathe under water. This is how they tend to get away with it. Frankly I'm amazed that Australian government hasn't been tried for environmental terrorism yet, but then how many more governments are at it too?
As you were saying to @realtreebivvy, most Aussies have been indoctrinated to hate carp (among other things) so anything from us probably comes in the region of conspiracy nuts.
They tell us it has no carry over effects. They said that about glyphosate and DDT also...
If nothing else, the inverts, insect larvae and crustaceans and the fish themselves are removed from the food chain.