Delegates at the World Summit on Sustainable Development in Johannesburg have reached agreement on ways to tackle the world's fisheries crisis.

Summit facts

60,000 delegates from 140 countries Estimated spending on travel: $2.2m Estimated fuel used: 36 million litres Estimated waste for 10-day summit: 600-700 tonnes Estimated production of greenhouse gas CO2: 300,000 tonnes Source: World Conservation Union

The deal - the first substantial one reached at the summit - envisages restoring most of the major global fisheries to commercial health by 2015.

This is the first agreement reached which has a specific date for completion. It will be incorporated in the plan of action at the end of the summit.

The deal emerged on the second day of the summit, with agriculture heading the agenda.

The BBC's Alex Kirby in Johannesburg says the agreement has eased the dour mood that marked the opening of the World Summit.

Extinction

Too many nets, too few fish

The deal will entail reducing catches to a level where the maximum sustainable yield can be taken indefinitely.

At the insistence of the US, the agreement stipulates that replenishment should happen "where possible".

The Americans point out that some stocks, like the cod on the Grand Banks off Canada's eastern seaboard, appear to have been fished beyond recovery.

But the agreement is also seen as a defeat for the US because it does specify a target and a timetable.

The Americans had argued that, instead of new targets, countries should try to keep to existing commitments.

40,000 delegates are attending the 10-day summit

The over-fishing problem is huge. The UN says more than 25% of the world's fisheries are over-exploited, 50% are being fished to their full capacity and 75% need immediate action to freeze or reduce fishing to ensure future supplies.

Our correspondent says the agreement means there is now global support for action.

Another section of the agreement provides for the establishment of marine protected areas across the planet by 2012, something which should give many endangered marine species a better chance of recovery.

Public discussions on agriculture have begun on the second day of the summit.

The first two sessions - on health and biodiversity - were not overwhelming successes, BBC correspondents reported.

Contentious issues

Observers say agreement on agriculture will prove difficult, as developing countries say that both the Europeans and Americans are not prepared to discuss reform of the world trade system and the reduction of subsidies to agriculture.

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Intense negotiations are also continuing behind closed doors on several contentious issues - including the use of cleaner energy and access to clean water for the developing world.

Observers have said the broad agenda of this summit creates almost endless scope for disagreements and is making consensus very difficult to achieve.

Delegates from the European Union have complained that their American counterparts are not prepared to sign up to specific targets on issues such as energy and water.

At the summit opening on Monday, South African President Mbeki urged delegates to come up with practical ways of tackling poverty and ending a world order based on the "survival of the fittest".