Species Focus - Orange Roughy (Hoplostethus atlanticus)
Orange roughy is a valuable commercial species. These fish are slow-growing, and long-lived. They are caught throughout the year, but the best catch rates are from June-early August, when they gather in dense groups to spawn (often over seamounts).
Orange roughy are caught from deep waters (800-1200 metres) by bottom trawling, with most catch being taken during the winter spawning season.
The main orange roughy fisheries are on the Chatham Rise, and off the southeast North Island/northern South Island. Most of New Zealand's orange roughy fisheries have had large reductions in catch over the years. They are now protected by low catch limits.
Status of the fish stocks
It is not easy to manage orange roughy fisheries sustainably. Because these fish live in such deep water, they are difficult and expensive to research. We have made mistakes with this species, but we also have successes.
The Soviets and Japanese began commercially fishing orange roughy in the late 1970s. New Zealand companies joined in shortly after, as orange roughy became a "boom" fishery. Total catches peaked at 54,000 tonnes in 1989. These fishers targeted dense spawning groups of fish. Initially, it was thought orange roughy would have similar growth rates and breeding success as other commercial species around the world.
However, by the late 1980s, scientists had discovered this was not the case. Orange roughy were found to be very long-lived (over 100 years) and slow growing. Unfortunately this came too late to save the Challenger (ORH7A) fishery, which has been effectively closed since 2000.
Today, we know more about these valuable fisheries and have become better at managing them. But there are still some big holes in our knowledge: we know little about how many young fish are out there, or the age structure of our fish stocks.
New Zealand's main orange roughy fisheries are on the Chatham Rise (ORH3B), and off the southeast North Island/northern South Island (ORH2A, 2B, 3A). All our orange roughy fisheries are managed towards producing the Maximum Sustainable Yield (MSY) of fish.
Assessments of fish stocks in these areas are done regularly, using a range of information. This includes trawl and acoustic surveys, information on the size of fish caught, and commercial catch / effort data.
The orange roughy stock on the northeast Chatham Rise appears to be in good shape, and is currently above management targets. This is the biggest orange roughy fishery in the world.
The southeast North Island/northern South Island roughy stocks also seem to be in good shape.
They appear to be rebuilding, and catch levels have been set in line with this.
Of our 11 roughy stocks, scientists think six are probably near or above the government's target level.
Three stocks are below the target (two of which have been closed), and the state of two exploratory fisheries is unknown.
Current management issues
The environmental damage caused by bottom trawling is an issue in this fishery, particularly as past fishing has damaged sensitive seamount habitats in a number of areas.
The government and industry are working together to limit further habitat damage in orange roughy fisheries.
During 2006, assessments are being done for orange roughy stocks around the Subantarctic Auckland Islands, the East Cape, Northeast Chatham Rise, and Northwest Chatham Rise.
Orange roughy catch limits and allowances
The catch limits and allowances for orange roughy have been set at 16,704 tonnes for the 2005/06 fishing year. Of this, the government has allocated 15,921 tonnes to commercial fishers. It has also allowed 793 tonnes to cover issues like illegal fishing (eg mis-reporting), and wastage or injury of fish.
Orange roughy fisheries are managed using a range of restrictions. Some of these protect the fish stocks (eg catch limits and voluntary industry restrictions within management areas). Others protect deep water habitats by closing some seamount areas to trawling.