Scientists in Australia have warned that fish piracy is damaging the Southern Ocean to such an extent that time is running out to save it.
Rewards for fish pirates far outweigh the risk of fines
Illegal fishermen, primarily on the hunt for the prized Patagonian toothfish (Dissostichus eleginoides), are wiping out both fish stocks and bird species that live in the ocean.
Species numbers are said to have dropped so acutely that Australia has called for global help to tackle the pirates.
"It is probably the last chance for us to get it right," Dr Adel Pile, of Sydney University, told BBC World Service's One Planet programme.
"The Southern ocean, this continuous mass of water, is really important, and [is] regulating globally things like our climate - El Nino starts in the Southern Ocean.
"If we mess around with the ecosystem enough that we can throw it out of balance, it's not just going to be limited to those of us who live in the Southern Hemisphere - it's going to have global ramifications."
Scientists say they know more about the surface of Mars than they do about the Southern Ocean.
Australia recently deployed an armed surveillance ship to protect fish stocks, but campaigners already fear the Patagonian toothfish has been hunted to near extinction.
Known as the "white gold" of Antarctica, the toothfish's flaky flesh is a delicacy in Japan and the US, and the strong demand for it in these countries has fuelled the illegal trade.
Demand from the US and Japan means the Patagonian toothfish is highly prized (Image by Caroline Raymakers)
Indeed, there are fears that many fish pirates operate with the corrupt support of governments in many countries.
As a result, Australia's fisheries minister Ian McDonald has said a unified international response is only way to combat the pirates.
"They are very active," he said. "We will be able to work more co-operatively with the British and the South Africans and New Zealanders.
"Together, I think we can form some sort of Southern Ocean coalition that jointly will embark on a major attack on this illegal fishing problem - and all of the consequences that come out of this illegal fishing."
There is so much concern because scientists believe that overfishing could have devastating environmental consequences.
The toothfish plays an important role in the Antarctic's marine ecosystem. It is part of the diet of the sperm whale and the elephant seal.
"They're all important, all the steps [in the food chain] - we can't afford to lose any of them," Matt Jacobs, of the Sydney Aquarium, told One Planet.
"If we lost a species, it could have repercussions on another species."
Mr Jacobs warned that the knock-on effect of destroying any one species would be felt by all, including humans.
"If you take out an apex predator like the great white shark, you'll end up with a larger seal population, which could in turn mean less fish," he said. "Professional fishermen then get affected, as well as everyone else."
Destruction is not only below the ocean's surface, it is also above it.
It is estimated 100,000 seabirds breeding on the sub-Antarctic islands are killed every year as a result of feeding on the long-line hooks used by illegal trawlers.
The seabirds are attracted to the baited hooks, strung out for kilometres across the ocean.
Fish pirates are also placing the albatross at grave risk
The birds get caught on the hooks, which are subsequently sunk. When this happens, the birds are pulled down and drown.
Nicola Bynin, of Humane Society International, said she believed some species were being slowly wiped out.
"The great albatross and petrels are probably the most endangered set of birds on the planet," she said.
"The reason they are going extinct is because of illegal poaching of the Patagonian toothfish."