Survey of orange roughy complete
NIWA and the Orange Roughy Management Company (ORMC) have just successfully completed their survey of the numbers of orange roughy on the eastern Chatham Rise.
The scientists used acoustic and trawling techniques to cover an area of 5100 square kilometres. The data will be used to estimate the numbers of orange roughy, for Ministry of Fisheries stock assessments which contribute to the setting of annual catch limits.
The survey picked up about 140 different fish species, and specimens of about 35 rare or unidentified species will be sent to Te Papa for further study.
The ORMC vessel San Waitaki conducted an acoustic survey of part of the area known as the Spawning Box on the northeast Chatham Rise, where the fish gather to reproduce (spawn) in July each year.
Two NIWA-operated vessels – NIWA’s deepsea research vessel Tangaroa, and a commercial vessel chartered from Endurance Fishing, Tasman Viking – surveyed orange roughy on selected flat areas of the seabed. NIWA also surveyed orange roughy which were spawning on two underwater seamounts, northeast of the Chatham Islands, about 250 kilometres from the Spawning Box.
In addition, Tangaroa returned to an area of the seabed where large numbers of juvenile orange roughy had been detected on previous research surveys in the 1980s.
Orange roughy don’t start reproducing until they are 30 cm long, or about 30 years old. The fish pictured below is just 5 cm long, making it between one and two years old. They live on the seafloor at a depth of between 750 and 950 metres.
The survey was funded by the Ministry of Fisheries and supported through industry levies.