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The Toothfishes of Antarctica: A Species of Special Concern

by Caitlyn Bishop Blog

Amongst the plethora of enigmatic species to find in the waters of Antarctica, the toothfishes is amongst the top of the list. You may know these species better by their supermarket alias, the Chilean Seabass, a name created by a fish wholesaler in the 1970s who was convinced the name ‘toothfish’ wasn’t attractive enough to buyers. Toothfishes come in two varieties.
Antarctic Peninsula

Regions: Antarctica

Destinations: Antarctic Peninsula, Ross Sea

The Toothfishes of Antarctica: A Species of Special Concern

Amongst the plethora of enigmatic species to find in the waters during an Antarctica cruise, the toothfishes is amongst the top of the list. You may know these species better by their supermarket alias, the Chilean Seabass, a name created by a fish wholesaler in the 1970s who was convinced the name ‘toothfish’ wasn’t attractive enough to buyers.

Toothfishes come in two varieties. The Antarctic toothfish (Dissostichus mawsoni) and Patagonian toothfish (Dissostichus eleginoides) both inhabit the coastal waters of Antarctica, are found in abundance around the Ross Sea at depths of up to 2,200 meters (7,218 feet), have cartilaginous skeletons instead of calcified bone, and can weigh up to 135 kilograms (300 lbs.)

Both are adapted to live in cold-water conditions, but unlike the Patagonian toothfish, the Antarctic toothfish’s blood contains antifreeze glycoproteins that allow them to survive in sub zero temperatures without freezing solid.

Mysterious Breeding Habits

Due to the inaccessibility of the toothfishes throughout their range and the length of time it takes for them to reach sexual maturity (typically 13 years for males and 17 years for females), scientists have had a difficult time understanding exactly how these fish breed. They are an exceptionally long-lived species, and have lived as long as 48 years. It is uncertain if they breed every year, or if they take time off from breeding every few years. Regardless, there are still many questions left for scientists to answer!

What Eats a Toothfish?

As one of the only major predators in this cold-water ecosystem, the Antarctic toothfish fills an ecological role that would normally be filled by sharks. The fish’s keen sense of smell and low light-adapted eyesight makes it a predator of almost every kind of small to medium sized fish in the Southern Ocean.

Oddly enough, they even lack a swim bladder, which allows them to stay neutrally buoyant at the bottom of the ocean without expending much energy. Thanks to neutral buoyancy, they can hunt and stalk prey for hours without having to move at all! Even the most fearsome of predators has to keep an eye out, however.

Other large, marine predators including sperm whales, killer whales, Weddell seals, and even the elusive colossal squid have been known to occasionally devour this tasty fish.

Overfishing and Conservation

During the 1980s and 1990s, global cod populations began to sharply decline. This drop in whitefish abundance encouraged commercial fisheries to focus their catch efforts in the Southern Ocean, where Antarctic and Patagonian toothfish are abundant. Unlike cod, their meat is high in fat and oils, making it impervious to even the worst cook in the kitchen. For the time being, the toothfishes were a viable alternative, and allowed cod populations to naturally reestablish themselves. However, this refocused pressure soon came with a cost.

By the mid 1990s, the Antarctic and Patagonian toothfishes were being caught in highly unsustainable and unregulated ways, which quickly led to their decline. Even today, over 3,000 tons of toothfishes are collected from the Ross Sea every year. In response to this noticeable population plummet, the Convention for Conservation of Antarctic Marine Living Resources (CCAMLR) established a fishery in 1997 in attempts to more staunchly regulate how and when these species were fished. As stipulated by CCAMLR, all fishing boats and ships were now legally required to take extra precautions when fishing to ensure bycatch of other marine species and seabirds did not occur, and were forbidden from dumping waste, including plastics, overboard at any time.

The establishment of this fishery was met with great opposition. Conservationists and biologists correctly pointed out that there wasn’t much known about these fish in the ways of basic ecology. How could anyone establish a fishery without knowing how or where the fish breed, how many eggs they lay, or how many young make it to maturity? It’s basic parameters such as these that need to be established in order to maintain a successful fishery. The reason why this data was missing, however, was due to the fact that these toothfishes are exceptionally elusive and live at extreme depths of the Southern Ocean, making them a difficult species to comprehensively study. Add to that the fact that they had been so heavily fished that there weren’t enough of them to study to yield a desirable amount of data to draw conclusions from. For now, research on these toothfishes has been at a standstill, as conservationists have focused more on keeping poachers away long enough to let the population revitalize itself. 

Poaching and Toothfishes

Poaching of toothfishes has unfortunately been a longstanding occurrence, despite the enforcement of regulations. Traditional methods of toothfish, and other marine fish poaching include dragging long line nets behind their vessel in order to catch as many fish as possible, or using gillnets. Both of these methods are extremely detrimental to the myriad of other sea creatures that accidently get swept up in these nets. Far too often, the net will be so filled with animals that the fishermen won’t even bother to pull them all out, and will simply drop the net back into the water, leaving them to die. This is commonly referred to as “bycatch”, and is one of the most detrimental aspects of poaching. After learning about the many atrocities committed on these fishing vessels, it’s easy to see why strict regulations need to be enforced.     

Considering the Southern Ocean is a difficult place for law enforcement to regularly patrol, many ships did not adopt CCAMLR’s code of conduct, and were quickly faced with heavy fines and even jail time if they were found to be fishing outside of regulations. Repeating offenders were subsequently blacklisted by CCAMLR, and their ship and captain’s name placed on a list monitored by Interpol. Vessels earning this level of international notoriety are commonly referred to as Illegal Unreported Unregulated or IUU vessels. Over the past several years, CCAMLR and even the famous Sea Shepherd have targeted and successfully captured six major vessels that have been responsible for a majority of toothfish poaching in the Southern Ocean. This was no small task, however, as the vessels frequently changed their name, crew, and location in attempts to hide out unscathed. Upon capture, the captains were faced with 32-36 months in prison and owed €15 million for environmental damage.

What Can You Do?

Unlike every other meat that is sold in the supermarket, it’s difficult to tell different species of fish apart just by looking at a few fillets on ice. This also makes lying about the type or quality of fish a lot easier for sellers as well. The best preventative measure is to ensure you’re eating sustainably caught and managed seafood is to check a seafood watch list before you head out to shop or to eat at a restaurant. Purchasing locally caught fish and other seafood, despite a hike in price, is another option, or you can buy a fishing license and catch it yourself!  

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