Tuna is an important commercial fish. Some varieties, such as bluefin and bigeye tuna, are threatened by overfishing, which dramatically affects Atlantic and northwestern Pacific Ocean populations. Other areas seem to support fairly healthy populations—for example, the central and western Pacific skipjack tuna—but there is mounting evidence that overexploitation threatens populations worldwide. The Australian government alleged in 2006 that Japan had illegally overfished southern bluefin by taking 12,000 to 20,000 tonnes per year instead of the their agreed 6,000 tonnes; the value of such overfishing would be as much as USD $2 billion. Such overfishing has severely damaged stocks. According to the WWF, "Japan's huge appetite for tuna will take the most sought-after stocks to the brink of commercial extinction unless fisheries agree on more rigid quotas".