Portuguese (Madeira) line fishery for black scabbardfish
Traditional deep-sea fisheries such as the Portuguese (Madeira) line fishery for black scabbardfish (Aphanopus carbo) is a rare example of a deep-sea fishery that, because it has traditionally used hook-and line-gear, has proved sustainable over a period of about 150 years (Martins and Fereira, 1995). Adults of this species are benthopelagic living in the depth range 400–1 600 m. It is a fast growing species with a life span of about 12– 14 years (Morales-Nin et al., 2002; Figueiredo et al., 2003). Landings in Madeira reached a maximum value of around 4 400 tonnes in 1998 and since then has steadily decreased to just below 3 000 tonnes in 2007 (Bordalo-Machado et al., 2009). The number of vessels active in this fishery has progressively decreased over time. However gear efficiency has increased mainly though an increase in the number of hooks per line set.
Hooks and lines

Trawling fisheries
The most commercially important deep-sea fisheries are those that are harvested by trawling. Many of these occur in association with seamount and seafloor ridges. Trawl fisheries using factory freezer trawlers started in the mid-1950s, primarily based on exploratory fishing conducted by large fishing fleet of the then Soviet Union. However, it was only later on, starting in the mid-1970s and further developing into the 1990s, that widespread exploitation of deep-sea regions began. This development was triggered by several factors including, among others, the introduction of EEZs. The establishment of EEZs excluded fleets that in the past had fished these waters and led some of them to look for new fishing grounds. Technological advances made fishing in the deep sea possible and commercially viable. Changes in the consumer perception of seafood, including the more widespread marketing of frozen products, also contributed to improved prices for deep-sea fishes.
Trawls

Orange roughy
The fishery for orange roughy is well known among recently developed deepsea fisheries. In New Zealand and southeast Australia, commercial fisheries began in the 1970s and 1980s; however, orange roughy was first described from the Azores. Fisheries later developed in the North Atlantic, on the Walvis Ridge in the Southeast Atlantic (Namibia) in the mid-1990s, off Chile also in the 1990s and in the Southwest Indian Ocean in 1999. A small fishery also exists in the Bay of Biscay. Specialized aimed-trawling techniques have developed. At first, massive catches from spawning aggregations could be taken in minutes, resulting in split codends and lost catches. Maximum sustainable levels of exploitation of orange roughy may be as low as or lower than 5 percent of unfished biomass, i.e. M ~ 0.04. Accumulating evidence indicates that few of these fisheries have been exploited sustainably, and it remains uncertain what ongoing yields will be. Smaller stocks usually do not escape depletion once they become targeted. However, there is conflicting evidence as to whether other stocks have proved more resilient to overexploitation, possibly because fishing disperses the fish before the stock is depleted, and because of episodic spawning. In this case, where fishing depends on spawning aggregations, not all of the stock may be vulnerable to capture in any one year as not all spawn each year (Butterworth and Brandão, 2005).

Macrouridae
The Macrouridae are another group whose members are widespread and abundant in particular locations. They are typical pelagic “cruisers” and inhabit the mid-to-upper continental slope. In the North Atlantic, fisheries that use bottom trawls exist for roughhead grenadier (Macrourus berglax) and roundnose grenadier. These fisheries initially fished in depths of 600–800 m, and more recently to 1 500 m. However, experience in these fisheries off Newfoundland shows the all-too-familiar pattern of TACs tracking declining trends in reported landings. The roundnose grenadier has a potential longevity of 70 years, although in the Northeast Atlantic, fish ages are usually of 20–30 years (Valerie and Pascal, 2000). Thus, as for other deep-sea species, Macrourids exhibit the characteristics of many deep-sea fisheries that render them particularly susceptible to overfishing.
Bottom trawls

Plaeuronectidae
The Pleuronectidae are a highly evolved group that is not usually associated with deep-sea fisheries. However, they constitute important fisheries as members of this group occur in both the North Atlantic and North Pacific Oceans. In the Atlantic, the best known has been that for Greenland halibut on the continental slopes and high seas. This fish had an average size in commercial catches of about 1 kg up until the mid- 1980s, but then declined to about 200 g in the early 1990s (Koslow et al., 2000).

Purse seine fishery for Blue whiting
The blue whiting (Micromesistius poutassou) is also often classified as a deep-sea species, although this species has generally higher growth rates and is highly productive and supports large fisheries. The blue whiting is a bathypelagic species found from 150–3 000 m depth, and is caught mainly by pelagic gear types. This species is caught by purse seiners in the Northeast Atlantic. The species can attain a length of 40 cm with an average length of about 31 cm (Campos, Fonseca and Henriques, 2003). Blue whiting is a straddling stock occupying the EEZs of Faeroe Islands, Norway, the countries of the EU, and Iceland as well as the high seas. Exploitation started in the 1970s, but has become increasingly important. However, since the record catch of this species of 2.4 million tonnes in 2004, the catches have decreased drastically and catches in 2009 were only about 640 000 tonnes. The decrease has been attributed to a fall in recruitment in 2006, declining spawning stock and reduction of quotas. For 2012, the ICES recommends an allowable catch of 391 000 tonnes. Recruitment remains low and is forecast to decline (ICES, 2011).
Purse seines

As for most of the other sections in the source volume the catch descriptions are based on FAO catch statistics – these are species reported to FAO by Member Countries. As mentioned above, there is no exact “definition” of what are regarded as “deep-sea fishes” and the type of fishes referred to may vary between different sources. Figure C4.1 shows the trend in catch of the deep-sea species listed in Table C4.1.. Unlike in the previous edition of this report (FAO, 2005), reported catches of largehead hairtail (Trichiurus lepturus) and Bombay-duck (Harpadon nehereus) have not been included as these two species have a wide distribution range. Much of the catch is taken in relatively shallow waters (Sissenwine and Mace, 2007), and it is difficult to determine which portion comes from deep-sea fishing. Moreover, in the catch reports to FAO, there is often no indication of the proportion caught in the high seas. The catches increased from the 1950s, and this occurred most rapidly between the mid- 1970s and the end of the 1990s. This pattern was particularly obvious in the Pacific and Indian Oceans. However, no information is available to attribute the changes between 1979 and 1998 to an increase in actual catches or better reporting. Peak catches were observed in 2003 and 2004, when catches of about 3.7 million tonnes were reported. Since then, reported catches have declined, and in 2009 total catches were about 1.8 million tonnes. This decreasing trend can in large part be attributed to the decrease in reported catches of blue whiting in the Atlantic Ocean that decreased from 2.4 million tonnes in 2004 to about 640 000 tonnes in 2009. Other species in the Atlantic Ocean with high average catch in the last five years (2005–09) include Patagonian grenadier (Macruronus magellanicus), Greenland halibut, southern blue whiting (Micromesistius australis) and ling (Molva molva). In the Indian Ocean, reported catches have generally been higher since 1997 compared with earlier years. They have been fluctuating between 125 000 and 195 000 tonnes, with the highest catch being observed in 1997. The hairtails and scabbardfishes (not identified) are the species group with the highest average reported catches in the Indian Ocean in the last five years. Other important species include Patagonian toothfish (Dissostichus eleginoides), blue grenadier (Macruronus novaezelandiae) and orange roughy (Hoplostethus atlanticus). With the exception of the Patagonian toothfish, reported catches have decreased for these species in recent years in this region. In the Pacific Ocean, catches increased until 1992, after which they began to fluctuate until 1998–99 (peak just below 1 million tonnes in 1998). Since then, catches in the Pacific have begun to decrease. Since 2004, reported catches in the Pacific have been in the range between 500 000 tonnes and 550 000 tonnes. Species with the highest average catches in this ocean in the last five years include the grenadiers (blue grenadier, Patagonian grenadier and grenadiers and rattails [not identified]), southern blue whiting and the groups tilefishes (Branchiostegidae) and hairtails and scabbardfishes.

Figure C4.1 - Annual nominal catches of deep-sea species

Orange roughy
The orange roughy (Hoplostethus atlanticus) of the family Trachichthyidae is a species with a wide distribution range that is found in the North and South Atlantic, the Southern Indian Ocean, the Tasman Sea, and the South Pacific. It inhabits continental slopes, seamounts and other bottom features and is commonly found at depths of 500–1 500 m. It is a slow-growing species, with a high age of first maturity and relatively low fecundity (Bell et al., 1992). This species exists as national, transboundary, straddling and high seas stocks. It is caught at depths over 800 m by fisheries that often target spawning aggregations associated with seamounts.
Figure C4.2 shows the catches of orange roughy reported to the FAO. Catches from the Pacific Ocean dominate, with only limited catches from the Atlantic and Indian Oceans in recent years. Catches for this species are decreasing, and catches in 2009 were about 13 000 tonnes compared with more than 91 000 tonnes in 1990.
The biological characteristics of this species (slow growth and exceptional longevity) and its aggregating behaviour make it vulnerable to overfishing. As such, many smaller fisheries for this species have been closed down as the stocks have been overexploited and the fishery has become commercially unviable. Stock assessments for this species are often uncertain, and lack of knowledge of recruitment is a main issue of concern for the management of this fishery (Dunn, 2007).

Figure C4.2 - Annual nominal catches of orange roughy

Oreo dories
The oreo dories (Allocystus spp., Neocystus spp. and Pseudocustus spp.) (Figure C4.3) are Oreostomadids that aggregate close to the sea bed in the deep-sea and form large shoals over seamounts and canyons. Similar to orange roughy, these species are also long-lived and slow-growing. The juveniles are pelagic and inhabit oceanic waters. They tend to be dispersed over smooth grounds. Their eggs float near the sea surface, and the larvae also inhabit surface waters. The species are caught both within national jurisdictions and on the high seas.
In Australian waters, spiky oreo (Neocyttus rhomboidalis) are more abundant at intermediate depths (600–800 m) and warty oreo (Alocyttes verrucosus) in deeper waters (900–1 200 m). Both species are benthopelagic feeders feeding on salps, crustaceans, fish and squid.
Figure C4.3 shows the reported catches of oreo dories NEI (not identified to species level), the black oreo (Alocyttes niger), smooth oreo dory (Pseudocyttus maculates) and spiky oreo indicating catches between 15 000 and 20 000 tonnes in the Pacific in the last five years. Up to 2001, species were recorded at an aggregated level, and since then catches have been reported for the species listed above.
As for many other species, management of these fisheries on the high seas is challenging because of a lack of data. Ageing data from Australia and New Zealand indicate that the maximum age for smooth is around 86 years, and 153 years for black oreo (Stewart et al., 1995; McMillan, 2008). Natural mortality for smooth oreo has been estimated at 0.063 per year, and 0.044 per year for black oreo. Estimates from New Zealand indicates the MSY to be of the order of 1.6 percent of B0 if the population is not to be reduced to a biomass of less than 0.2 B0 (probability < 0.2) (Doonan and McMillan, 2006). For operational reasons, where they are managed at all, smooth, black and spiky oreos have been managed as a single stock with the associate dangers this implies (Annala, Sullivan and O’Brien, 1999).

Figure C4.3 - Annual nominal catches of Oreo dories

Alfonsinos
The alfonsinos (Beryx sp., Bericidae) have a circumglobal distribution although they are generally not present in the northeast Pacific. They inhabit the outer shelf (180 m) and slope to at least 1 300 m depth, probably rising from the bottom at night. Reported catches of this genus are mainly B. splendens and B. decadactylus. Beryx splendens are caught in midwater trawls over shallower seamounts, underwater ridges and on the slope edge between 300 and 500 m. The juveniles are pelagic. There is no common agreement on the stock structure for alfonsino and contradictory information is available supporting different hypothesis (ICES WGDEEP, 2010). Alfonsino are caught both within national jurisdictions and on the high-seas.
Figure C4.4 shows that catches of alfonsinos have fluctuated widely, with high catches at the end of the 1990s and the first decade of 2000. The highest catch was in 2003 (just over 14 000 tonnes). Since then, catches have generally decreased and, in 2009, catches of about 5 000 tonnes were reported. Highest catches are reported from the Pacific, where this species constitutes one of the main target species in the trawl and gillnet fisheries in the high seas areas of the Northwest Pacific (Bensch et al., 2009). Catches are also reported from the Atlantic and Indian Oceans, although almost no catches have been reported from the Indian Ocean in recent years. This low level of catch may also be linked to national reporting restrictions which apply to fisheries operating with a limited number of vessels.
The maximum recorded age for this species range from 9 years (Krug et al., 2011) to 23 years (Adachi et al., 2000; Froese and Pauly, 2011) and become sexually mature at about 4 years of age. Natural mortality is estimated to be about 0.23. Thus, they offer a greater prospect of sustaining the deep-sea fisheries that target them. Little is known about the local area stock structure of these species, and it is for example believed that the New Zealand fishery may be exploiting a wider South Pacific stock (Annala, Sullivan and O’Brien, 1999).

Figure C4.4 - Annual nominal catches of alfonsino

Toothfish
Toothfish (Dissostichus spp.) of the family Notothenidae, have a circumpolar distribution within Southern Ocean waters. Patagonian toothfish (D. eleginoides) are found around southern South America, and Antarctic toothfish (D. mawsoni) occur in high latitudes south of the Pacific region. The two species overlap between 60°S and 65°S, and both occur to depths of 3 000 m. The northern limit for most populations of Patagonian toothfish is 45°S, except along the coasts of Chile and Argentina where they may extend north in deeper colder water. Significant populations of Patagonian toothfish exist in the waters of, and adjacent to, the various sub-Antarctic islands and in the waters of Chile, Argentina, Uruguay and Peru. Figure C4.5 indicates that most catches of toothfish have been reported in the Atlantic and Pacific Oceans in recent years, with total reported catches of about 10 000–12 000 tonnes since 2004.
The problem of IUU has been considerably reduced in recent years. However, it still remains a major concern in many regions. Toothfish mainly fall under the management responsibility of the CCAMLR (see Chapter B16 for further information on toothfish).

Figure C4.5 - Annual nominal catches of toothfish

Pelagic armourhead
The armourheads belong to the family Pentacerotidae and inhabit seamounts, especially in the North Pacific but also in other oceans. There are three species of armourhead, the pelagic armourhead (Pseudopentaceros richardsoni), the slender armourhead (P. wheeleri) and longfin (P. pectoralis), but only the pelagic armourhead is currently reported in FAO catch data.
Figure C4.6 shows that reported catches of pelagic armourhead have stayed quite low, with a peak of reported catches in the Atlantic in 1991 of about 1 200 tonnes. However, historically, substantial catches of pelagic armourheads NEI (Pseudopentaceros spp.) were reported in the late 1960s and early 1970s, reaching almost 1.8 million tonnes in 1973. The slender armourhead – often also referred to as pelagic armourhead was the target of a large fishery in the high seas of the North Pacific starting in the late 1960s. At this time, vessels from Japan and the then Soviet Union began trawling on the Emperor Seamount chain and the Northern Hawaiian Ridge. The total catch for the Soviet vessels was unknown but was estimated to be more than 133 400 tonnes in the period 1967– 1977. Between 1969 and 1977, the Japanese sent from two to five trawlers a year to this area and catches ranged from 22 800 to 35 100 tonnes a year. Ninety percent of the catch was of pelagic armourhead. Catches then fell to 5 800– 9 900 tonnes between 1977 and 1982.

Figure C4.6 - Annual nominal catches of pelagic armourhead

Blue grenadier (hoki)
Blue grenadier or hoki (Macruronus novaezelandiae) is a benthopelagic macruronid that usually lives near the bottom but forms midwater aggregations for spawning. Large adult fish generally occur deeper than 400 m, while juveniles may be found in shallower water. Midwater trawl fisheries target aggregations near canyons that are often close to coasts in areas of narrow continental shelves. Figure C4.7 shows the reported catches of these species, which are mainly caught in the Pacific. Reported catches decreased from more than 300 000 tonnes in 1998 to about 100 000 tonnes in 2009.
Knowledge of the stock structure for this species is often uncertain. Management experience in at least some jurisdictions indicates that this resource can be sustainably managed. In the major global fishery for this species, in New Zealand, the TAC has changed from time to time as the size of the hoki stocks varied. The TAC in New Zealand has fluctuated between 200 000 and 250 000 tonnes in earlier years, being reduced gradually from the year 2000, down to 90 000 tonnes in 2007 and 2008 as the spawning stock declined. This decline is also believed to have been influenced by ENSO-related oceanographic events. Subsequent to this, the TAC has again increased to 130 000 tonnes for the coming season as a result of the rebuilding of stocks in recent times.

Figure C4.7 - Annual nominal catches of blue grenadier