The Patagonian toothfish, (Dissostichus eleginoides), and Antarctic toothfish (Dissostichus mawsoni) are deep sea species found throughout large areas of the sub-Antarctic oceans, but primarily in the Southern Ocean and adjacent southern parts of the Atlantic and Indian Oceans. In some markets it is also known as Mero, Chilean Sea Bass and Black Hake.
Toothfish are bottom dwelling, in depths of 300 metres to 3500 metres, but move off the bottom on occasion to feed. They are found primarily in easterly banks and appear to thrive best near land. Consequently, the fishing grounds are concentrated on continental shelves around the islands in the region.
This species can be fished to depths of 3,500 metres. However this varies with large fish of spawning age fished at a depth, generally between of 1,400 and 2,000 metres, while smaller toothfish are found in shallower waters.
The Patagonian toothfish grows slowly and reaches spawning age between 8 and 10 years, at which stage it is about 80cm long. The fish can reach an age of around 45 years, a maximum length of 2.2 metres and about 120 kg in weight. Its diet is mainly based on squid, fish, crabs and prawns. The Antarctic toothfish has very similar biological characteristics, but is thought to grow a bit slower than Patagonian toothfish, and has a smaller maximum length (estimated at around 1.8 metres). These differences in growth, and sexual maturity, as well as the lifespan of the fish, are all taken into account by scientists in the annual reassessment of population status, and the setting of allowable catches.
Commercial Patagonian toothfish fisheries began in the late 1980s off the coasts of Chile and Argentina, including the Falkland Islands. Over time, fisheries began further eastwards via South Georgia, Bouvet Island, Prince Edwards and Marion Islands, Crozet Island, Kerguelen Island, Heard Island and McDonald Islands, as well as Macquarie Island. There are also artisanal fisheries for Patagonian toothfish off the continental slopes of Chile, Argentina and Uruguay.
The Antarctic toothfish fishery began later, as the fish tend to be found only in very southern latitudes and alongside the Antarctica icepack. The main legal fishery for Antarctic toothfish is in the Ross Sea, in FAO Divisions 88.1 and 88.2. Click here to read a FAQ document regarding Antarctic toothfish and the Ross Sea
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 between 45 and 60 degrees South. 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, there are two main methods of fishing permitted. 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) and the second major method is 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:
- 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
- No fishing during periods when the birds are known to be feeding their chicks (seasonal closures)
- Boats must use weighted longlines so that the baits and hooks sink before the birds can grab them; and
- 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).
Fishing by trawling does not usually harm seabirds but does tend to catch 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.
By-catch species (fish caught incidentally to the ‘target’ species) when fishing for toothfish are also closely monitored by CCAMLR. There are catch limits imposed on all by-catch species to ensure that the levels of catch do not exceed biological or ecologically sustainable levels. Longline fishing methods catch low amounts of skates and rays, and trawl fishing methods also has a very low by-catch rate in the sub Antarctic, with the total by-catch of other species less than 2% by weight of the target species, toothfish. On all fishing boats for toothfish in CCAMLR waters there are at least one, and often two, government-approved observers monitoring all aspects of fishing operations.
From the mid 1990′s to the mid 2000′s, IUU fishing for toothfish was a very serious problem. In recent years, however, IUU fishing has been reduced to a fraction of its former levels due to a combination of increased surveillance, high-profile apprehensions and prosecutions and strict port and market regulations. Estimates of IUU catches are built into the toothfish stock assessment process, and allowable catches for legal boats have been reduced accordingly.
Illegal, unreported and unregulated (IUU) fishing of toothfish was originally undertaken by longline fishing boats, with serious consequences for seabirds. However, from the mid 2000′s onwards, the remaining IUU fleet switched to gillnet operations. Whilst this method is potentially destructive to other fish by-catch species, it poses less risk to seabirds. Equally, the reduction in numbers of IUU boats from a peak of 55 longliners (none applying any mitigation measures to avoid catching seabirds) in the late 1990′s, to the current day (2012) estimate of 4 IUU boats using gillnets, has dramatically reduced the estimated negative impacts on seabird populations.
A number of toothfish fisheries have received certification by the Marine Stewardship Council as sustainable and well-managed fisheries. These fisheries have the ability to use Chain of Custody certification, in addition to the CCAMLR Catch Documentation Scheme. In addition to the MSC, most toothfish is now rated as Best Choice or Good Alternative by the Monterey Bay Aquarium Seafood Watch program.
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