An infestation of crabs in the Ngunguru estuary looks set to be permanent and may already be impacting on the local ecology.
The unwanted and aggres-sive Asian paddle crab species (Charybdis japonica) appears to have made itself at home in the estuary, said Don McKenzie, Northland Regional Council biosecurity manager.
More than a dozen crabs have been caught by council staff or members of the public since the invader was first noticed there in late 2014.
The species is widespread in the Hauraki Gulf and has been detected in small numbers in Whangarei Harbour and Opua/Waitangi.
"We're unsure how these paddle crabs have ended up in Northland, although the most likely scenario is probably that they have arrived as an unwanted hitchhiker on a fouled boat hull or in ballast water from other parts of New Zealand," Mr McKenzie said.