Scientists are using new technology to determine the number of orange roughy in New Zealand waters.
A team of scientists from the Commonwealth Science and Industrial Research Organisation has been aboard fishing company Sealord's vessel Otakou.
The scientists have been using state of the art acoustic equipment to determine fish numbers in areas such as the Northwest Chatham region, east of the South Island.
One of the scientists, Tim Ryan, says they've been attaching equipment to the fishing vessel's trawl net rather than mounting it on a boat, so they get a much more accurate count of orange roughy.
The Forest and Bird Best Fish Guide rates orange roughy as red or unsustainable.
Last month, the Ministry for Primary Industries discovered a new and substantial group of orange roughy in the Chatham Rise area.