Species including tuna and the orange roughy are among those under threat by illegal fishing and the notorious practice of bottom-trawling, by which heavy rollers are dragged over the ocean floor, trapping fish and mammals and destroying entire ecosystems.
The most imperilled species are within international waters, which account for more than half the world's surface. Many governments are ignoring controls on them and allowing pirate fishing vessels to operate unchecked, said Simon Cripps of WWF's marine programme.
Countries such as Australia, Britain and Canada should be taking more responsibility, setting examples and putting pressure on other states, he said.
The WWF report, co-written with the wildlife trade monitoring network Traffic, was released before a meeting next week in New York in which governments will review the UN Fish Stocks Agreement, the legal framework for managing fish populations in the high seas.
The environmental devastation being caused by a global fishing industry whose catch has risen from 18 million tons to 95 million tons over the past half-century, has left 25 per cent of commercial species over-exploited and depleted, compared with 10 per cent in the mid-1970s, according to the UN's Food and Agriculture Organisation.
The WWF, based in Switzerland, found that some of the regional fisheries management organisations (RFMOs), whose task it is to ensure waters are not overfished, lacked the "political will and commercial motivation" to enforce fishing limits.
Some regional agreements, such as the Antarctic Convention, do protect fish stocks, concluded the WWF. But some signatories to a North Atlantic agreement are ignoring fishing quotas altogether.
Canada, for example, is committed to protecting stocks in its own national waters but allows over-fishing on the Grand Banks, off its east coast, because they fall within international waters where vessels from other nations are at work. This is causing huge declines in cod stocks, devastating the income of coastal communities.
Some countries seem oblivious to the environmental damage being caused. The coastal states of East Africa are not part of their own region's RFMO - the Indian Ocean Tuna Commission - despite catching large amounts of tuna. Several East African states are being used as trans-shipment ports for illegally-caught toothfish, but do not seem aware of the illegality.
Graphic evidence of the consequences of such systemic failures arrived from Rome yesterday where, at the start of the commercial fishing season for the Mediterranean bluefin tuna, the Tuna Trap Producers Association (TTPA) said that their industry was on the verge of collapse.
Catches by the traditional tuna-trap fishermen in southern Spain are down 80 per cent on this time last year, according to the TTPA.
The WWF said the root of this crisis lay with one of the RFMOs whose role is examined in the report - the International Commission for the Conservation of Atlantic Tunas (ICCAT), which was allowing an increase in the Mediterranean tuna farming capacity, taking the total authorised capacity to 51,012 tons, some 20,000 tons higher than a previously imposed limit.
The report's authors called on the UN to review fishing on the high seas, and strengthen the resolve of RFMOs to deal with states that flout agreements.
"It's got to stop, we've got to do it quickly," Mr Cripps said. "There is hope, if we can get management put in place."