Out of the known deep-sea organisms one that is little known is Hoplostethus atlanticus, the orange roughy. This fish is commonly found between 500 and 1800m, and often stays close to the seafloor, and as a result are targeted by deep-sea trawlers. Orange roughy commonly vary from 35-50cm, with some individuals reaching 75cm and weighing 7kg. In recent years, the average size of the population is thought to have decreased as a result of low recruitment levels and overfishing.
Following the discovery of orange roughy stocks, many fisheries immediately started fishing without considering the life cycle and replacement level of the fish, resulting in a fairly swift decline in stocks, often below levels of long-term sustainable yield. The roughy fishery is still relatively young, opening in New Zealand in the late 1970’s. Since then, a number of other fisheries have been opened and swiftly closed due to poor stock management. However, in 2016 the New Zealand fishery was certified by the Marine Stewardship Council, becoming the first sustainably caught orange roughy, and creating a management plan others could follow in a bid to improve sustainability of these fisheries.
Rise of Roughy
Orange roughy have a wide, but scattered, global distribution, but are more common in the Southern Hemisphere (figure 1). The roughy are distributed in cold, deep waters of the Pacific, Atlantic and Indian oceans, with commercial fisheries established off New Zealand, Australia, Namibia, Ireland, Chile and the South Indian Ocean. They are found on steep continental shelfs and ocean rises, and aggregate around seamounts and canyons, such as the Graveyard seamounts on the Chatham Rise for feeding and spawning. Little is known about the environmental factors affecting spawning (which is not annual), and why it occurs at seamounts (though roughy are synchronised spawners). As it is a fairly meaty fish, orange roughy is popular for both local consumption and exports, particularly to the United States, where it is popular as an alternative to red meat (a healthier option).
Orange roughy off the coast of Canterbury, New Zealand have been found to be over 100 years old – with one individual estimated to be 149 years old (calculated from otolith ring counts and radio-isotope ratios). Longevity of orange roughy is thought to be affected by the environment (low temperatures, high pressure, limited oxygen levels and food). Studies on roughy have shown a low mortality rate (<5% per year), however recruitment appears to be variable, with low numbers of mature adults for extended periods. This discovery led to a hypothesis as to whether there is a link between longevity and recruitment variability.
Make the date before the plate
As a deep water fish, it is characteristically slow growing with a low fecundity, only reaching maturity after 20-30 years. The average age of roughy caught in trawls is 30-50 years old, making it particularly susceptible to overfishing; as is often the case, this issue was realised as populations crashed. Prior to any management strategies being implemented, a decline in roughy stocks was observed in roughy fisheries globally.
The roughy was first fished commercially off New Zealand (which contributes over 50% of the worlds orange roughy), where it quickly became the most important fin fish species. As the meat holds together well and is tolerant of most cooking methods it quickly became popular in both Australia and New Zealand (and can be used as a substitute for other commonly cooked fish like cod and haddock).
In Australia, roughy populations were heavily fished in the late 1980s, peaking in 1990 before a total ban on the fishery was enforced in 2006. Once the source of fish was found, figure 2 clearly shows that the resource was immediately exploited before populations rapidly depleted.
The Irish roughy fishery has a similar story. The North Atlantic commercial fishery opened in 2001, and started as a ‘non-quota’ and open access fishery. Landings peaked in 2002, but due to rapid stock declines, many fishing vessels had to drop out; by 2005 the fishery was more or less closed.
Future of fish?
In many cases to prevent a complete stock collapse orange roughy fisheries have been, at lest temporarily, closed (as seen in Australia and Ireland). As well as being the first country to commercially fish orange roughy, New Zealand currently boasts the worlds only sustainable orange roughy fishery, certified in December 2016. However it is only after 20 years of careful management and advances in scientific innovation that the fishery was able to receive MSC certification (accounting for 60% of New Zealand’s catch).
Getting the orange roughy fishery to a point where it can be both sustainable and economically viable has taken about 40 years of trial and error. Technological advances, allowing for visual and acoustic monitoring, has enable fisheries to monitor stocks.
Fisheries need to consider the socio-economic benefits of the stock. The North Atlantic fishery found that deep sea trawling for roughy had limited social benefits (profit and job production) and was not economically sustainable, and as a result, have placed temporary ban as a precautionary measure. The Australian Fisheries Management Authority has come up with a management strategy in preparation for re-opening their orange roughy fishery after more than 10 years. This strategy limits harvesting, only permitting fishing when stocks are >20% of un-fished levels, and restricting fishing to certain areas.
While off to a rough(y) start, the commercial orange roughy fisheries are looking at the future viability of stocks. In some cases, this resulted in a semi-permanent closure of the fishery, and in others it has led to the development of management strategies. In the future it is expected that further steps will be taken to improve the sustainability of orange roughy fisheries, following the lead of those in New Zealand and Australia.