Geez, they moved closer very quickly. They've been found on a couple of islands quite close to PNG. Apparently they make good bait for Niugini Black Bass. They have supposedly moved east from West Papua. The biggest threat would be locals catching them on the islands and transporting them closer. They can live for a fair while out of the water.
http://www.abc.net.au/news/2015-06-0...tralia/6512986