Out of the well known deep sea organisms, this one is unlikely to be on your list! Hoplostethus atlanticus, or orange roughy (so called for it’s bright colour) is commonly found between 500 and 1800m. The fish are not thought to undergo any migration (vertical or otherwise), and often stay only 10-50m from the seafloor. The size of the fish commonly varies from 35-50cm (ranges of size differ with location), 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.
Although they tend to be found in large aggregations, this fishery is still relatively young, opening in New Zealand in the late 1970’s. Following the discovery of the orange roughy stocks, many fisheries immediately started fishing without considering the life cycle and replacement level of the stocks, which resulted in a fairly swift decline in stocks, often to levels below long-term sustainable yield.
Rise of Roughy
Orange roughy have a global distribution, but are more common in the Southern Hemisphere (as seen in figure 1). The roughy are distributed in the cold, deep waters of the Pacific, Atlantic and Indian oceans, with commercial fisheries established off the coast of 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. Roughy are often found to feed and spawn in aggregations around these seamounts. Little is known about what environmental factors affect spawning (which does not occur annually for all adults), and why it occurs at seamounts (though it is known that roughy are synchronised spawners). As it is a fairly meaty fish, orange roughy is a popular fish for both local consumption and for exports, particularly to the United States, where it is popular as an alternative to red meat (for those trying to be healthier).
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). The longevity of this deep sea fish is thought to be a result of the environment (low in temperature, high pressure and limited oxygen levels and food). The current growth rate of these fish is under scientific debate, but some aged juveniles have been sized between 3cm and 9cm during the first 4 years. Studies on roughy have shown them to have a low mortality rate (<5% per year). Recruitment appears to be variable, with low numbers of mature adults for extended periods of time. This discovery has 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, while the average age of roughy caught in trawls is 30-50 years old. This makes it particularly susceptible to overfishing, and as is often the case, we only realised this issue as populations crashed. Prior to any management strategies being put in place, a decline in roughy stocks was observed in all roughy fisheries.
The roughy was first fished commercially off New Zealand (which contributes over 50% of the worlds orange roughy), and quickly became the most valuable fin fish species in the country. As the fish has a meat that holds together well, is tolerant of most cooking methods and retains moisture while cooking 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, the 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, it is clearly seen in figure 2 that the resource was immediately exploited before populations were 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 a rapid decline in stocks, many fishing vessels had to drop out, and by 2005 the fishery had largely been closed.
Future of fish?
In many places where roughy has been fished (for example Australia and Ireland) in order to prevent a complete collapse of the fish stocks the orange roughy fishery has had to be, at lest temporarily, closed. As well as being the first country to commercially fish orange roughy, New Zealand currently boasts the worlds only sustainable orange roughy fishery (certified by the Marine Stewardship Council in December 2016), however it is only after 20 years of management that the fishery was able to receive MSC certification.
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 improved the ability of the fishery to monitor stocks. The current sustainable stock is the result of 20 years carefully managing fish stocks and advances in scientific innovation. The MSC certified orange roughy now accounts for 60% of New Zealand’s catch.
When considering fishing orange roughy, the fishery needs 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. For the sack of the future of this particular stock, a temporary ban has been put in place as a precautionary measure until more evidence is gathered. 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 includes harvest control rules, only allowing fishing when stocks are >20% of unfished biomass. Only restricted areas are allowed to be harvested.
While off to a rough(y) start, the commercial orange roughy fisheries are looking at the future viability of the fish stocks. In some cases, this has resulted in a semi-permanent closure of the fishery, and in others it has led to the development of management strategies. It is expected that in future there will be more steps taken to improve the sustainability of orange roughy fisheries, following the lead of the New Zealand and Australian fisheries.