Antarctic and Patagonian toothfish are large, demersal predators belonging to the cod icefish family (Nototheniidae). They are distinctive in that they live in southerly waters influenced by the Antarctic Circumpolar Current, reaching depths between 300 and 2,500 meters; the coldest waters on Earth. As a result of this freezing habitat Antarctic toothfish have evolved antifreeze-like proteins in their tissue, which along with their life cycle and distribution, we know very little about. Living up to 48 years, they can grow as long as two meters and weigh up to150 kilograms. It is believed they reach sexual maturity between 13 and 17 years of age.
During the late eighties/early nineties the market for toothfish, better known by its market name of Chilean Sea Bass, exploded as fisheries sought alternatives for dwindling cod populations. With its flaky, white flesh and high oil content, toothfish are near impossible to overcook, making them highly prized in restaurants and high-end markets around the world. Like the Atlantic Cod, the culinary popularity of the Antarctic and Patagonian toothfish led to a serious decline in toothfish stock in waters surrounding Chile and Argentina.
In 1993 official records report a 30,000 ton catch increase over the previous year, which stood at just under 1,000 ton. With little toothfish left in localised waters, fishermen with bigger ships and better machinery were sent further afield to wipe out greater numbers.
Toothfish are vulnerable to overfishing, not only because they're long-lived and slow to mature, but also because they tend to stay in one place. The fishing industry targets large, old fish and researchers are mostly reliant on legal toothfish operators for data, which is alarmingly limited.
Poaching of Patagonian and Antarctic toothfish is so lucrative that illegal fishermen call it "white gold". The Thunder alone is estimated to have made profits in excess of $US 60 million during its operations in Antarctica.
Three years of Illegal, Unreported, Unregulated (IUU) fishing led to the collapse of the toothfish populations and subsequent closure of fisheries around Prince Edward and Marion Islands. Populations around Crozet Island were reduced by 45% during a similar time period. Although increased enforcement efforts have resulted in the recovery of some fish populations, IUU fishing has shifted to new populations that aren’t afforded the protection of surveillance and patrolling.
Illegal toothfish operators use a number of prohibited fishing methods, including gillnets. The use of gillnets is forbidden due to the high risk of incidental catch of sea birds and marine mammals, as well as the risk that lost or abandoned gillnets will become "ghost nets" that continue to kill fish indefinitely.