Orange roughy

The orange roughy, also known as the red roughy, slimehead and deep sea perch, is a relatively large deep-sea fish belonging to the slimehead family. It is bathypelagic, found in cold, deep waters of the Western Pacific Ocean, eastern Atlantic Ocean, Indo-Pacific, and in the eastern Pacific off Chile. The orange roughy is notable for its extraordinary lifespan, attaining over 200 years. The fish has a bright, brick red color, fading to a yellowish-orange after death.
Like other slimeheads, orange roughy is slow-growing and late to mature, resulting in a very low stock resilience, making them extremely susceptible to overfishing. Despite this, the species is important to commercial deep-trawl fisheries; many stocks became severely depleted within 3–20 years, but several have subsequently recovered to levels that fisheries management believe are sustainable, although substantially below unfished populations. The UK Marine Conservation Society has categorized orange roughy as "vulnerable to exploitation".

Description

The orange roughy is laterally compressed, typical for its family. Its rounded head is riddled with muciferous canals, also typical of slimeheads. The single dorsal fin contains four to six spines and 15 to 19 soft rays; the anal fin contains three spines and 10 to 12 soft rays. The 19 to 25 ventral scutes form a hard, bony median ridge between the pelvic fins and anus. The pectoral fins contain 15 to 18 soft rays each; the pelvic fins are thoracic and contain one spine and six soft rays; the caudal fin is forked. The interior of the mouth and gill cavity is a bluish black; the mouth itself is large and strongly oblique. The scales are ctenoid and adherent. The lateral line is uninterrupted, with 28 to 32 scales whose spinules or 'ctenii' largely obscure the lateral line's pores. The eyes are large.
The orange roughy is the largest known slimehead species at a maximum standard length of and a maximum weight of. The average commercial catch size is commonly between in length, again, varying by area.

Life history

Orange roughy are generally sluggish and demersal; they form aggregations with a natural population density of up to 2.5 fish per m², now reduced to about 1.0 per m². These aggregations form in and around geologic structures, such as undersea canyons and seamounts, where water movement and mixing is high, ensuring dense prey concentrations. The aggregations are not necessarily for spawning or feeding; the fish are thought to cycle through metabolic phases and seek areas with ideal hydrologic conditions to congregate during each phase. They lose almost all pigmentation while inactive, when they are very approachable. Predators include large, deep-roving sharks, cutthroat eels, merluccid hakes, and snake mackerels such as oilfish.
When active, juveniles feed primarily on zooplankton, such as mysid shrimp, euphausiids, mesopelagic and benthopelagic fish, amphipods, and other crustaceans; mature adults consume smaller fish, predominantly of the Butterflyfish and Lanternfish families, and squid, which make up to 20% of their diet. The diet of the orange roughy is depth-related, with adult diets inversely related to that of juveniles. For example, juvenile consumption of crustaceans is lowest at but increases with depth, while crustaceans in the adult diet peak at and decrease with depth. The consumption of fish is the opposite: juvenile consumption decreases with depth while adult consumption increases. This inverse feeding pattern may be an example of resource-partitioning to avoid intraspecific competition for the available food at depths where prey is less abundant. The orange roughy's metabolic phases are thought to be related to seasonal variations in prey concentrations. The inactive phase conserves energy during lean periods. Orange roughy can live for over 200 years.

Reproduction

Orange roughy are oceanodromous, pelagic spawners: that is, they migrate several hundred kilometers between localized spawning and feeding areas each year and form large spawning aggregations and sperm en masse directly into the water. The fertilized eggs, are planktonic, rising to around to develop, with the young fish eventually descending to deeper waters as they mature. Orange roughy are also synchronous, shedding sperm and eggs at the same time. The time between fertilization and hatching is thought to be 10 to 20 days; fecundity is low, with each female producing only 22,000 eggs per kg of body weight, less than 10% of the average for other species of fish. Females rarely produce more than 90,000 eggs in a single spawning event. Spawning may last up to three weeks and starts around June or July. Orange roughy are very slow-growing and do not begin to breed until they are at least 20 years old, when they are around in length.
The maturation age used in stock assessments ranges from 23 to 40 years, which limits population growth/recovery, because each new generation takes so long to start spawning.

Lifespan

When commercial fishing of orange roughy began in the 1970s, they were thought to live for only 30 years. Since the 1990s, however, there is clear evidence that this species lives to an exceptional age. Early estimates of 149 years were determined via radiometric dating of trace isotopes found in an orange roughy's otolith ; counting by the growth rings of orange roughy otoliths gave estimated ages of 125 to 156 years. One specimen caught 1500 km east of Wellington in 2015 was estimated to be over 230 years old. Orange roughy caught near Tasmania have been aged at 250 years. The orange roughy is the longest-lived commercial fish species, and does not breed every year, which has important implications for its conservation status.

Consumption

The flesh is firm with a mild flavour; it is sold skinned and filleted, fresh or frozen. This species was first given the common name "Orange Roughy" by scientists in New Zealand in 1975 following the discovery of large aggregations during a deep-water research cruise. A large-scale fishery for orange roughy subsequently developed around New Zealand, and imports into the United States increased where it was renamed from the less gastronomically appealing "slimehead" through a U.S. National Marine Fisheries Service program during the late 1970s that identified underused species that should be renamed to make them more marketable.
Historically, the United States has been the largest consumer of orange roughy; however, in recent years, the market for orange roughy in China has increased significantly. In 2014, the U.S. imported around 1,455 tonnes from New Zealand, China, Peru and Indonesia. In 2015, China imported at least 4,000 tonnes .
A number of major food retailers have established seafood sustainability policies to reassure customers that they are stocking sustainable seafood. These policies often involve partnering with non-governmental organizations to define criteria for seafood that may be stocked. In addition, a number of ecolabels exist to help retailers and consumers identify seafood that has been independently assessed against a robust, scientific standard. One of the best known such programmes is that of the Marine Stewardship Council.
In 2010, Greenpeace International added orange roughy to its seafood red list, which contains fish generally sourced from unsustainable fisheries.
A 2003 joint report by the TRAFFIC Oceania and World Wildlife Foundation Endangered Seas Program argues that "probably no such thing as an economically viable deep-water fishery that is also sustainable." However, others have argued that deepwater fisheries can be managed sustainably provided that it is recognized that sustainable yields are low and catches are set accordingly.
Because of its longevity, the orange roughy accumulates large amounts of mercury in its tissues, having a range of 0.30–0.86 ppm compared with an average mercury level of 0.086 ppm for other edible fish. Based on average consumption and the recommendations of a National Marine Fisheries Service study, in 1976 the FDA set the maximum safe mercury level for fish at 1 ppm. Regular consumption of orange roughy can have adverse effects on health. Compared to most edible fish, orange roughy is a very poor source of omega-3 fatty acids, averaging less than 3.5 g/kg.

Fisheries

Orange roughy fisheries exist primarily in New Zealand, Australia and Namibia. Annual global catches began in 1979 and increased significantly to a high of over 90,000 tonnes in 1990. These high catch levels quickly decreased as stocks were fished down. For many stocks, the lack of understanding of the biological characteristics meant that they were overfished. By the end of the 1990s, three of the eight New Zealand orange roughy fisheries had collapsed and were closed. Because of its longevity, late maturation and relatively low fecundity, orange roughy stocks tend to recover more slowly than most other species.
A number of orange roughy stocks live outside the jurisdiction of any particular nation, making it more challenging to limit overall catches. The South Pacific Regional Fisheries Management Organisation and the South Indian Ocean Fisheries Agreement have orange roughy stocks that are managed within their jurisdictions. These organizations have made progress toward collecting better information on total orange roughy catches and also with setting catch limits for fisheries on the high seas. For example, SPRFMO limited orange roughy catches and effort from 2007.
Orange roughy is fished almost exclusively by bottom trawling. This fishing method has been heavily criticized by environmentalists for its destructive nature. This, combined with heavy commercial demand, has focused criticism from both environmentalists and media.

New Zealand fisheries

New Zealand currently operates the largest orange roughy fisheries in the world, with a total catch of over 8,500 tonnes in the 2014 calendar year. This accounts for 95% of the total estimated catch of orange roughy. Exports of orange roughy provided an estimated revenue to New Zealand of NZ$53 million in 2015.
Fisheries in New Zealand are managed through the Quota Management System, under which individuals or companies own quota shares for a stock of a particular species or species group. For each stock, a Total Allowable Catch is set that maintains the stock at or above a level that can produce the maximum sustainable yield or that will move the stock toward that level. Orange roughy has been managed within the QMS since 1986.
The Ministry for Primary Industries is responsible for the implementation of the QMS and its enabling legislation, the Fisheries Act 1996.