Fish stocks in international waters are being plundered to the point of extinction, a leading conservationist group has said.
Illegal fishing and bottom-trawling in deep waters are to blame, according to a report from WWF.
It says the current system of regional fishing regulation is failing to tackle the problem, with not enough being done to enforce quotas or replenish stocks.
It says species under severe threat include tuna and the orange roughy.
The orange roughy is targeted by bottom-trawlers, which drag heavy rollers over the ocean floor, destroying coral and other ecosystems.
"Given the perilous overall state of marine fisheries resources and the continuing threats posed to the marine environment from over-fishing and damaging fishing activity, the need for action is immediate," Simon Cripps, director of WWF's global marine programme, said.
Illegal fishing "by highly mobile fleets under the control of multinational companies" was identified as one of the worst threats to marine life.
But the report also attacked governments for over fishing.
"Vast over-capacity in authorised fleets, over-fishing of stocks... the virtual absence of robust rebuilding strategies... and a lack of precaution where information is lacking or uncertain are all characteristic of the management regimes currently in place," it said.
The report was released ahead of a New York meeting on the United Nations Fish Stocks Agreement, the legal framework for the management of fish stocks on the high seas, next week.
BBC science reporter Matt McGrath says that on the high seas - away from the protection of national quotas - fish stocks are at their most vulnerable.
The regulation of fishing in these international waters is the responsibility of regional fishing management organisations - made up of countries with a vested interest in the area.
According to WWF, most are failing to manage fish stocks in a sustainable way.
Decision-making is poor, it says, and the regional organisations are powerless to control the activities of countries who ignore regulations.
This backs up the conclusions of an analysis last year from the conservation group BirdLife International, which concluded that a majority of the regional fisheries organisations are failing to take their responsibilities seriously.
The authors are calling on the United Nations to review fishing on the high seas and strengthen the resolve of regional authorities 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."