The Patagonian toothfish, Dissostichus eleginoides, marketed as Chilean sea bass in the United States and Canada, is a fish found in cold waters (1–4 °C or 34–39 °F) between depths of 45 m (148 ft) and 3,850 m (12,631 ft) in the southern Atlantic, Pacific and Indian Oceans and Southern Ocean on seamounts and continental shelves around most sub-Antarctic islands.
A close relative, the Antarctic toothfish (Dissostichus mawsoni), is found farther south around the edges of the Antarctic shelf; and a Marine Stewardship Council (MSC) certified fishery is active in the Ross Sea.
The average weight of a commercially caught Patagonian toothfish is 7–10 kg (15–22 lb), depending on the fishery, with large adults occasionally exceeding 100 kilograms (220 lb). They are thought to live up to fifty years and to reach a length up to 2.3 m (7.5 ft). Several commercial fisheries exist for Patagonian toothfish which are detailed below.
The Latin name for Patagonian toothfish is Dissostichus eleginoides. It is sold under the trade names Chilean sea bass in the USA; Merluza negra in Argentina, Peru and Uruguay; Legine australe in France; Mero, in Japan and Bacalao de profundidad in Chile.
The name "Chilean sea bass" was invented by a fish wholesaler named Lee Lantz in 1977. He was looking for a name that would make it attractive to the American market. He considered "Pacific sea bass" and "South American sea bass" before settling on "Chilean sea bass". In 1994, the U.S. Food and Drug Administration (FDA) accepted "Chilean sea bass" as an "alternative market name" for Patagonian toothfish.
In the UK, the approved commercial designations for D. eleginoides and D. mawsoni are 'icefish' and 'toothfish'. This has created some confusion as there is a genuine 'icefish' (Champsocephalus gunnari) caught in subantarctic waters, which does not resemble toothfish in any way.
Patagonian toothfish spawn in deep water (around 1,000m) during the austral winter, producing pelagic eggs and larvae. Larvae switch to a demersal habitat at around 100mm (1 year old) and inhabit relatively shallow water (<300m) until 6–7 years of age, when they begin a gradual migration into deeper water. As juveniles in shallow water, toothfish are primarily piscivorous, consuming the most abundant suitably sized local prey. With increasing size and habitat depth, the diet diversifies and includes more scavenging of squid, fish, and crustaceans. In turn, toothfish constitute a small part of the diets of sperm whales, southern elephant seals, and colossal squid.
As most toothfish fisheries are managed in accordance with CCAMLR regulations and conservation measures, it should be noted that CCAMLR adopts an “ecosystem approach” which requires that all other living resources of the Southern Ocean are treated as an integrated system where effects on predator, prey and related species are considered, and decisions on sustainable harvesting levels are made on the basis of sound, internationally peer reviewed scientific advice.
Commercial fishing of toothfish is managed by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) inside the CCAMLR Convention Area which spans the Antarctic continent and waters between 45°S and 60°S. Some fisheries inside territorial waters within the Convention Area (e.g. Crozet Island, Prince Edwards and Marion Islands) are managed separately by countries with territorial waters taking CCAMLR management practices into account. Toothfish fisheries outside the CCAMLR Convention Area in the coastal waters of Argentina, Chile and Uruguay are managed by the relevant coastal state. However, these fisheries are still subject to the CCAMLR Catch Documentation Scheme (CDS) which tracks the trade of toothfish from the point of unloading to the point of final consumption.
In the legal toothfish fisheries managed by CCAMLR and countries with territorial waters, the most common method is fishing by longlines (where a long ‘mainline’ is set in the water, with many baited hooks coming off that line). There is a small amount of toothfish caught by trawling (where a net is towed behind the boat for short periods of time). For all methods of legal fishing for toothfish, there are minimal interactions with seabirds these days. This is a result of requirements for legal operators to use mitigation devices or approaches such as:
- Seasonal fishery closures during the summer months due to increase in seabird abundance for chick rearing;
- No setting of hooks during the daytime;
- No fishing without having a bird-scaring line trailing out the back of the boat to keep birds away from the hooks;
- Bird Exclusion Devices (BED) or 'brickle curtain' to be used on 100% of hauls;
- Boats must use weighted longlines so that the baits and hooks sink before the birds can grab them;
- Limitations on release of offal overboard at the same time as the setting or hauling of lines (to avoid attracting seabirds when they may otherwise be vulnerable to the baits and hooks).
In 2011 the CCAMLR Scientific Committee Chair, David Agnew, was quoted as saying “levels of seabird mortality are negligible in most areas”, with the one region yet to achieve these ‘near zero’ results, having reduced seabird interactions by over 98% from their peak levels, and have continued to improve each year.
Trawling generally catches toothfish in the smaller size range, which requires calculations to be made at the annual stock assessment meetings of CCAMLR to take these catches of smaller sized fish into account, and lowers the overall available catch of toothfish by trawl. CCAMLR has prohibited all trawl fishing in high seas waters and exploratory fisheries.
To minimise the risk of long-term adverse effects on target species, by-catch species and marine ecosystems, CCAMLR uses a number of compliance systems to monitor fishing activities in the Convention Area. This includes:
- Vessel licensing;
- Monitoring of transhipments;
- Vessel and Port inspection systems;
- Automated satellite-linked Vessel Monitoring Systems (VMS);
- Catch Document Scheme:
The Catch Documentation Scheme (CDS) for Patagonian toothfish (Dissostichus eleginoides) and Antarctic toothfish (Dissostichus mawsoni) was one measure that ensured reductions in illegal fishing for toothfish and reduced the scope for trade in illegally caught fish. The CDS is an innovative online catch document information system (DCD: Dissostichus Catch Document) developed to identify legal toothfish harvested, which tracks toothfish from the point of landing throughout the trade cycle to point of sale. The CDS requires verification and authorisation by national authorities at regular intervals in the trade cycle. Identification of the origin of toothfish entering the ports and markets of CDS Parties is essential.
Legal fishing 
The Coalition of Legal Toothfish Operators, Inc. (COLTO) is a toothfish fishing industry body whose members represent over 84% of the legal toothfish catch worldwide. Four of the fisheries that are fished by COLTO members are now independently certified by the Marine Stewardship Council (MSC) as sustainable and well managed fisheries, and a further two fisheries are currently undergoing full assessment against the independent MSC standards. Commercial fishing of Patagonian and Antarctic toothfish is managed by CCAMLR around most of the sub-Antarctic and Antarctic regions, however the fisheries that lie within a nation’s Exclusive Economic Zones (EEZ) are managed by those nations, taking into account management recommendations and approaches by CCAMLR.
In 2004, the South Georgia toothfish fishery (CCAMLR Statistical Division 48.3) was the first toothfish fishery to be MSC certified, and was recertified in 2009, as all MSC certified fisheries must be audited annually, and fully reassessed every five years. Currently, the South Georgia Total Allowable Catch (TAC) is 3,000t, and there are 6 longline vessels being operated by 5 companies in this fishery, who are managed by the UK overseas territory of South Georgia and the South Sandwich Islands.
The Ross Sea fishery (CCAMLR Statistical Division 88.1 and 88.2) was the second toothfish fishery to be independently evaluated and certified by the MSC as sustainable and well managed (in 2010). This fishery catches mainly Antarctic toothfish, a close relative to the Patagonian toothfish.
The Heard Island & McDonald Islands fishery (CCAMLR Statistical Division 58.5.2) was certified as a sustainable and well managed fishery by the MSC in March 2012 and is operated under Australian jurisdiction in a manner consistent with CCAMLR regulations. There are 3 vessels operated by 2 Australian companies (Austral Fisheries and Australian Longline). The CCAMLR determined TAC is 2,730t of toothfish for the 2011/12 and 2012/13 seasons.
The Macquarie Island toothfish fishery is within the Australian EEZ, and is situated outside the CCAMLR Convention Area within FAO Statistical Area 81, though is managed in a complementary way with the conservation measures adopted by CCAMLR. In May 2012, this was the fourth toothfish fishery to gain MSC certification. There are 2 Australian companies that are allocated to catch 455t of toothfish in 2012/13.
Combined, over 30% of all legally harvested toothfish is independently assessed and certified by the MSC as being from sustainable and well managed fisheries. Currently, several other toothfish fisheries are in the process of independent review for MSC certification.
France regulates Patagonian toothfish in the waters surrounding the French islands in the South Indian Ocean. These are the Crozet Islands (CCAMLR Statistical Division 58.6) and Kerguelen Islands (CCAMLR Statistical Division 58.5.1), with scientific oversight from the National Museum of Natural History. Fishing authorizations have been granted to 6 fishing companies based out of Reunion Island (before 1998, there had been agreements with other countries authorizing their ships to fish in these waters). The current TAC for Crozet is 800t, while at Kerguelen the TAC is 5,000t. Both French fisheries are currently under full assessment by the MSC.
The Falkland Islands, a self-governing British Overseas Territory also has a toothfish fishery and is the most recent to have announced it is under full assessment by the MSC. The Falklands do not fall in the CCAMLR Convention area, though regulations on fishing methods, science and management mirror CCAMLR requirements. The TAC is currently 1,200t and is caught by a sole longline vessel.
The Chilean toothfish fishery is separated into two separate fleets. The artisanal fleet of small boats which operates in the region north of 47°S inside the Chilean EEZ and 11 vessels from the ‘industrial fleet’ who operate south of 47°S inside the Chilean EEZ as well as on the high seas both within and outside CCAMLR waters. The TAC for the industrial fleet is determined each year by the Chilean Government based on biological studies carried out by both public and private scientific bodies. The current Chilean TAC for the industrial fleet is 3,090t that is caught by 11 vessels from 4 companies. Since 2006, artisanal fleet catches have fluctuated between 2,091t and 1,558t per annum.
Argentina has a toothfish fishery off its coastline that is managed by the Argentine Federal Fisheries Council under recommendations from the National Fisheries Research Institute. This season the Argentine TAC is 3,500t that is caught by 7 vessels from 4 companies.
The Prince Edward and Marion Islands toothfish fishery is managed and regulated by Branch Fisheries, part of the South African Ministry of Agriculture, Forestry and Fishing. The South African Marine Resource Authorities fully supports and follows all CCAMLR Conservation Measures. The current TAC is 320t and is fished by 2 vessels belonging to 2 fishing companies/cooperatives, with catches restricted significantly following excessive illegal, unreported and unregulated (IUU) fishing in those waters in the late 1990s.
The total allowable catch of toothfish worldwide is around 23,500t in 2011/12, with 84% of this coming from COLTO members, and 31% of the total catch (7,272 tonnes) now being independently certified as coming from sustainable and well managed fisheries by the Marine Stewardship Council (with three other fisheries totalling 7,000 tonnes under full MSC assessment).
It is estimated by CCAMLR that around 6% of the worldwide toothfish catch is taken by IUU operators, and that product does not have the current Catch Documentation System evidence trail associated with it, so cannot be sold legally into major markets including USA, EU, and Japan.
Illegal fishing 
In the late 1990s to early 2000s, illegal, unreported and unregulated fishing (IUU) for toothfish nearly collapsed some fisheries in the Southern Ocean. Though, since 2005, thanks to CCAMLR Member nations, government patrol vessels, NGOs, media exposure and a trade and port state measures, IUU fishing has been all but eliminated from within countries' exclusive economic zones, though a relatively small portion of IUU fishing still occurs in high seas areas.
At the peak of IUU fishing, illegal catches were estimated to be 32,000 tonnes in 1997 with approximately 55 vessels believed to be active. By 2010, IUU catches had fallen to an estimated 1,615 tonnes, all taken in high seas areas, with just four IUU fishing vessels reported to be active. This is a decrease in IUU fishing by over 95% since the mid 1990s. CCAMLR estimates that 90% of IUU catches are now of Antarctic Toothfish, not Patagonian Toothfish.
CCAMLR annually reviews information on IUU fishing activities in the Convention Area and has established a Contracting Party and a Non-Contracting Party IUU Vessel List (CCAMLR Conservation Measure 10-06 and Conservation Measure 10-07). Vessels included on the IUU Vessel Lists have engaged in IUU activities in the Convention Area and undermined the effectiveness of conservation measures, thereby threatening toothfish stocks, marine habitats and by-catch species. Vessels are included on the IUU Vessel Lists after a consensus decision from the Commission based on set criteria. This measure, combined with additional surveillance by member nations, catch documentation schemes has played a significant part in the reduction of IUU fishing for toothfish.
In the past, France sold some fishing rights to Japanese and other foreign fisheries, but because of IUU fishing, rights are now reserved for French fishers based at Réunion Island. Because of poaching, the French Navy and Australian Customs vessels work in tangent, patrolling both French and Australian EEZs and made numerous arrests and seizures in the late 1990s to early 2000s. An Australian Customs vessel, the Southern Supporter, was involved in the renowned chase and apprehension of an IUU vessel in the 2003 Viarsa incident that stretched over 7,200 kilometers.
TACs for legal operators in CCAMLR are set, taking into account the estimated IUU catches from past years, and any current IUU activity that may be occurring in the different fisheries. In some fisheries this has meant a considerable reduction in legal catches – an example of this is the Australian Heard Island and McDonald Islands fishery, where the legal TAC peaked in 1996/97 at 3,800t. This was dropped to a minimum of 2,427t by 2006/07 with a substantial portion of that decline attributed to the IUU catches taken from the fishery between 1996 and 2002. Since then there has been zero IUU fishing in that fishery, and the legal TAC is currently 2,730t for the 2011/12 season.
In addition to the Catch Documentation System mentioned above, USA regulations do not allow toothfish imports without valid Dissostichus Catch Documents; and dealer permit and pre-approval certificates issued in advance by NOAA. In addition, toothfish must be caught from vessels equipped with satellite-linked automated VMS that track vessel movements from port-to-port to ensure compliance with set quotas and boundaries. All vessel VMS data must be reported to the centralized CCAMLR system, with confirmation to USA required that it has occurred, in order for any products from those boats to be imported into the United States.
The EU has also imposed requirements against IUU fishing that include:
- Only marine fisheries products validated as legal by the relevant flag state or exporting state can be imported to or exported from the EU.
- A European black list having been drawn up covering both IUU vessels and states that turn a blind eye to illegal fishing activities.
- EU operators who fish illegally anywhere in the world, under any flag, face substantial penalties proportionate to the economic value of their catch, which deprive them of any profit.
Seafood Chooser Organisations 
Chilean Seabass (Patagonian toothfish)is currently listed by the Monterey Bay Aquarium on its Seafood Watch list and pocket guides. In April 2013, Seafood Watch produced an updated report, indicating new ratings for some fisheries, which allocates approximately 78% of toothfish caught worldwide, which are as follows:
Best Choice - Heard Island and McDonald Islands Fishery (Australia), Macquarie Island Fishery (Australia), Falkland Islands Fishery
Good Alternative - South Georgia Fishery, Kerguelen Islands Fishery (France), Ross Sea Antarctic toothfish Fishery
Avoid - Prince Edward & Marion Island Fishery (South Africa), Chile, Crozet Islands Fishery (France)
Not Rated - Argentina
In 2010, Greenpeace International added the Patagonian toothfish to its seafood red list. "The Greenpeace International seafood red list is a list of fish that are commonly sold in supermarkets around the world, and which have a very high risk of being sourced from unsustainable fisheries."
In light of numerous recent MSC certifications for toothfish fisheries, some 'seafood chooser' organisations are currently reviewing their previous rankings on this species. For example, the Australian Marine Conservation Society website states:
"CURRENTLY UNDER REVIEW: Toothfish (Patagonian & Antarctic) Wild.
Due to improvements in Australian management of the Macquarie Island and Heard and MacDonald Island toothfish fisheries, AMCS is currently undertaking a review of the ranking for toothfish. There has been significant effort and progress to reduce the impact of the fishery on seabirds and the reduction of Illegal, Unregulated and Unreported fishing in the Australian fishing zone."
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