Project to unveil stingray secrets

A manta ray

A university marine scientist is hoping to unlock many of the secrets surrounding the large migratory fish species that cruise the New Zealand coastline.

"There's a dearth of information on these species. We have very little idea of numbers, where they come from, where they congregate or where they go after leaving our waters," says Dr Steve Cook of AUT, co-researcher of the Bigfish project.

The Bigfish team are working with boaties and commercial fishing vessels to record sightings of ocean-going plankton feeders, which include devil and manta rays.

Dr Cook says these large fish species can be individually identified by their unique colour patterns and scars. The data collected from sightings and photos will be used to create an "image bank" to help scientists better understand the animals' distribution and behaviour.

"Over time, we should be able to find out where these species come from, where they spend most of their time in New Zealand, and whether the same individuals are visiting each year."

The Bigfish project is an independent project set up by Dr Cook; DOC Marine Conservation Officer, Clinton Duffy; and AUT PhD candidate and Sealab community environmental advisor, Dan Godoy. The team are also intending to observe the habits of whale and basking sharks.

Depending on the level of public support and funding, the team hope to put satellite tags on some of these big fish to track their movements after leaving New Zealand waters.

The manta ray can grow up to eight metres and Dr Cook says boaties and divers should observe a few key rules when approaching these large ocean dwellers. These include keeping boat speed well below six knots and maintaining a distance of at least 3 metres in the water.

"Rays are benign gentle giants, but they are big animals and capable of defending themselves, should they be startled or feel threatened."

Dr Cook, who has dived with a school of 50 stingrays at the Poor Knights Islands, describes Steve Irwin's fatal attack as "seriously bad luck".

"From all accounts it seems Irwin wasn't doing anything to disturb the ray, so perhaps it just got startled."

- AUT UNIVERSITY