Fish have been feasting on the copious amounts of mice swarming NSW, raising fears a new rodent poison could harm native wildlife as well. Recreational anglers have discovered first-hand just how widespread the mice are as snacks for the fish.
“It’s well-known native fish eat rats and mice, and we’re aware of reports of native fish having mice in their stomachs in parts of the Murray-Darling Basin,” OzFish project manager Braeden Lampard said.
A picture posted to Twitter by ABC reporter Lucy Thackray highlighted the phenomenon in a revolting fashion. It shows several partly decomposed mice that were discovered inside a Murray cod.
The fish consider the mice so tasty that some anglers have unique lures resembling rodents that they bring out during mouse plagues, Mr. Lampard said.
But wildlife advocates worry that appetite for mice could put the fish in danger if the state government succeeds in having a new, super-strong poison approved for use against the mice.
NSW Agriculture Minister Adam Marshall has advocated for the federal government to allow the use of bromadiolone to kill mice, a poison he has compared to “napalm”.
The anticoagulant agent kills the rodents by inhibiting the production of vitamin K, which is needed for blood to clot. After being exposed to bromadiolone, a mouse will bleed to death once its vitamin K reserves are exhausted, typically a few days after being poisoned.
“It would be catastrophic,” said Healthy Rivers Dubbo spokeswoman Mel Gray about the prospect of bromadiolone being approved. “With bromadiolone, it can take up for a week for a mouse to die, and in that time, they’re out there being prey. This stuff will pass along the food chain and cause our population of Murray cod to bleed to death en masse.
“There is a reason bromadiolone is banned.” Mr. Marshall has asked the Australian Pesticides and Veterinary Medicines Authority to approve the use of bromadiolone to stop the mouse plague.
It would be applied through a government-led program where farmers could have their grain treated with the poison. More than 400 farmers have already put their hand up to get access to the toxin once it’s approved, Mr. Marshall said on Sunday.
“Landholders will be able to surround their crops with bromadiolone-treated grain, which when used in combination with zinc phosphide to kill off mice already in the paddock, will give farmers a multi-layered defense,” Mr. Marshall said.
Zinc phosphide is the only poison currently registered for use in large-scale cropping systems. The ongoing rodent infestation across eastern Australia is on track to cause up to $100 million worth of damage and has already worsened a mental health crisis in the regions.
Some farmers have lost as much as $300,000 each in ruined crops as the mice chew through anything they can get their teeth in. The advocacy group NSW Farmers has also opposed the use of bromadiolone, echoing the concerns wildlife and livestock could be harmed.