- Scientific name: Hoplostethus atlanticus
- Also known as: Slimehead, Deep Sea Perch, Redfish, Orangefish, Red Roughy
- Size: Up to 2ft in length and 10lbs
- UK minimum size: N/a
- UK shore caught record: N/a
- IUCN Status: VU (Vulnerable)
- Distribution: Very deep sea fish which is not widespread around the UK. Main populations are found in the deepwater Rockall Trough lying to the west of the British Isles. Also found in many other deep water environments around the world, although commercial pressure is seeing numbers and distribution of this species shrink.
- Feeds on: Mostly feeds on small fish and squid.
- Description: Deep bodied and laterally compressed fish. One dorsal fin, the first part of which has noticeable spines. The lateral line curves upwards and is made up of distinctive large scales. The head is contains mucus producing organs and the mouth is relatively large and upturned. Despite its name the orange roughy is actually more of a reddish colour when alive (as shown above), although this changes to orange when the fish is dead and removed from the water.
The orange roughy is a deep sea fish which was previously ignored by the commercial fishing industry. However, since the 1970s this species has been exploited heavily for human consumption and there has been a corresponding crash in both its numbers and distribution. The orange roughy is often used as a perfect example of how deep sea fish cannot be harvested sustainably, and the plight of this species has received considerable media and public attention.
Distribution and Habitat
Orange roughy live at depths down to several thousand metres, meaning that only deep sea areas can support this species. This means that their distribution around the British Isles is limited to the Rockall Trough to the west of Ireland and, to a lesser extent, the Faroe-Shetland Channel to the north of Scotland. They do, however, have a worldwide distribution. They are found throughout the north east Atlantic and along most of the western coast of Africa, although they are absent from the Mediterranean and the Black Sea. They are also found on parts of the eastern coast of the USA and Canada and in the waters around the South American Continent, particularly along the coastline of Chile. They are found in the Indian Ocean and in the waters around Australia and New Zealand. Orange roughy are known to congregate in large numbers on the seabed around seamounts (underwater mountains), ridges and other underwater features. Intensive commercial exploitation has led to aggregations of orange roughy becoming less dense, and there is concern that distribution of this species is receding as the numbers drop.
Feeding and Behaviour
Although they are relatively slow and sluggish they are still capable of catching small fish and squid, and will also feed on deep-water prawns, amphipods and other small crustaceans. Orange roughy are thought to go through phases when they are mostly inactive and do not feed. During this time the fish is slow and sluggish and their colour fades. This may be an adaptation to their deep sea environment and a way of coping when there is no food available.
Reproduction and Lifespan
Orange roughy gather on the seabed in large shoals to spawn, with small groups of fish making short local migrations to join the larger breeding shoals. Once gathered the females release eggs, but only tens of thousands, contrasting with most other marine fish species which release hundreds of thousands or even millions of eggs. Furthermore orange roughy are an extremely slow growing and late maturing fish. They are thought to be able to live for up to 150 years, and cannot reproduce until they are aged 20-30 years.
Orange roughy were ignored by the commercial fishing industry until the 1970s, when the decline in traditional whitefish stocks (cod, haddock) and the advances in trawling technology made it commercially viable to fish for deep sea species. The discovery of orange roughy, and the quick emergence of a market for this species, led to a ‘gold rush’ mentality – wherever orange roughy was found it was fished intensively. As orange roughy gather together in shoals on the sea bed large amounts of fish could be caught in a relatively short amount of time meaning that vast catches were made by commercial vessels. It was during this time that the name of this species changed from slimehead to the more appealing orange roughy or deep sea perch – a classic case of re-branding a fish to make it more appealing to consumers.
Australian and New Zealand stocks of orange roughy were intensively fished throughout the 1980s and 1990s, with New Zealand fishermen alone taking 100,000 tons of orange roughy every year. By the early 2000s it was clear that this intensity of fishing was unsustainable and the numbers of orange roughy were being decimated. By the mid-2000s the Australian Marine Conservation Society stated that stocks of orange roughy had been fished down to around 10% of their 1970s. The population of orange roughy in the Rockall Trough was also exploited commercially, with Charles Clover stating in his 2004 book The End of the Line that “Orange roughy populations [from the] Rockall Trough have been mined out within a few decades of being found.”
The extremely late age at which orange roughy mature, along with the low number of eggs produced by females mean that orange roughy will take an incredibly long time to repopulate stocks which have been reduced by commercial fishing. It is thought that in some areas where orange roughy have numbers have been reduced they will take many decades to return to their former numbers.
The Future for Orange Roughy
There is now much more awareness of the trouble that orange roughy stocks are in, and much more consumer awareness about the declining numbers of orange roughy. Many organisations such as Greenpeace and the Marine Conservation Society state that orange roughy should be avoided due to their endangered status and this has led to the Australian, New Zealand and American authorities imposing commercial fishing limits and restrictions in an attempt to allow orange roughy numbers to recover. There is evidence that orange roughy numbers do show improvement after long-term fishing restrictions have been imposed, and if fishing intensity permanently is reduced there may be a chance of recovery for the orange roughy.