Walking fish on march to mainland
A WALKING fish that has invaded the Torres Strait could continue spreading towards Australia’s mainland.
The aggressive climbing perch has already overrun Australia’s two most northerly outposts, the islands of Boigu and Saibai, which are 4km and 6km south of the Papua New Guinea mainland.
The perch can live out of water for up to six days, and has the ability to crawl over dry land.
James Cook University scientists have been monitoring the invasive fish’s spread in partnership with Torres Strait communities.
The fish are proving very difficult to eradicate from the two islands, despite being first officially recorded there as far back as 2005.
Team member Dr Nathan Waltham said there was now evidence the freshwater species could tolerate exposure to salt water.
“It does seem to be able to handle a bit of salt,’’ he said.
“In our trip up there in December, we found it in some hyper-saline waterholes.’’
The fish drags itself from waterhole to waterhole and is very invasive, out-competing native species.
It can hibernate in the mud of dried-up creek beds for up to six months.
It swells up when swallowed by larger predators, blocking their throats so they either choke or starve.
Dr Waltham said the fear was it would arrive reach the mainland in the bottom of a fishing boat or as discarded live bait.