Climbing perch, an invasive freshwater fish that can crawl on land by its gills and live out of water for up to six days, would be a "major disaster" if they ever reached Australia, and they appear headed in that direction.
The aggressive climbing perch, known to choke birds and other fish when swallowed, are native to Southeast Asia and have spread south through Indonesia and Papua New Guinea in the past four decades, according to Australian Broadcasting Corporation and The Guardian.
Climbing perch have now populated the waterways of Boigu and Saibai, two Queensland islands situated less than seven miles off the southern coast of Papua New Guinea and 99 miles off the northernmost tip of mainland Australian.
Researchers and rangers are monitoring the climbing perch closely, worried they might somehow migrate to mainland Australia.
Nathan Waltham, a senior researcher at James Cook University, told The Guardian if the invasive fish did reach the mainland it would be a "major disaster" for certain native fish species and other wetland dwellers. In Papua New Guinea, Waltham discovered barramundi, catfish and some aquatic birds that died after ingesting climbing perch, also known as Anabas testudineus.
"Their gill covers, they can flex them out and get caught in the throats of fish and birds, so that leads to the animal dying," Waltham told ABC.
The climbing perch grow up to 9.8 inches and breathe on land through lungs that are next to their gills. They are known to hibernate in the mud of dried-up creek beds for up to six months.
Waltham said on a December trip to the two islands he observed climbing perch living in very salty waterholes, the equivalent of ocean water, but he doubts the fish could reach mainland Australia by swimming.
Of more concern is that they arrive in the bottom of a fishing boat or as discarded live-bait fish.
"Anecdotes are that they are carried between villages on various islands," Damien Burrows of James Cook University told ABC. "So a trip in a boat across the Torres Strait is not out of the question."
The research team is attempting to educate fishermen and residents to help them identify the fish and throw them out before venturing to mainland Australia.
"When they populate an area they're not commonly found in, they can disrupt the balance of that habitat," Waltham told The Guardian. "That's why we're working with Torres Strait authorities to make sure they don't spread further south…
"Only with ongoing education and surveillance are we going to prevent climbing perch from arriving in northern Australia."
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