Northland's marine reserves, wrecks and reefs are increasingly becoming home to fish species from sub-tropical waters.
Five new or rarely seen species have been spotted at east coast dive spots during the past two months but the latest has scientists differing on whether it's a scribbled leatherjacket or a unicorn triggerfish.
The
rare fish was captured on film last week at the Canterbury wreck near Deep Water Cove, Bay of Islands.
It joins a list of recently seen yellow boxfish, black-spot goatfish, eyestripe surgeon fish, two-tone wrasse and damsel fish.
Northland Dive partner Julia Riddle posted the photo taken by Charlie McVicar on Wade Doak's website discussion forum to try to find out whether the 50cm fish was a triggerfish or leatherjacket.
Te Papa marine biologist Andrew Stewart thought the long dorsal spine on the fish pins it as an Aluterus scriptus, or juvenile scrawled (scribbled) leatherjacket. Those spines become smaller as the fish grows, he said.
"I have also seen a photograph of another one, caught in the Northland area by a commercial vessel.
"It is a relatively rare find, and is only known in the New Zealand region from photographs," Dr Stewart said.
The species, found in tropical and subtropical inshore areas worldwide, usually around reefs, grows to a metre long.
Malcolm Francis of Niwa thinks it's a close relative of the leatherjacket - the unicorn triggerfish or Aluterus monoceros.
"Both species have been recorded before in northern New Zealand waters but are very rare. They are semi-pelagic and associate with drifting seaweed and logs, hence can travel long distances on ocean currents," Dr Francis said. The artificial reef created by the Canterbury wreck at Deep Water Cove has become a magnet for warmer water species. Last Saturday, divers spotted a small turtle.
Mr Doak said a valuable amount of information was being collected by recreational divers coming across new and rare species in Northland dive spots.
"Wrecks provide a huge range of habitats within a short range. So do offshore islands, even if close inshore," Mr Doak said.
Some experts are putting the increase in warm water marine life down to the La Nina weather pattern which has heated the ocean around New Zealand by up to one degree.
Te Papa's Dr Stewart said records and species which have either been photographed or collected this year indicate there has been a "pulse" of warmer water species into New Zealand's northern waters.
