By Richard Black
Environment correspondent, BBC News website
Turtles are among the creatures put at risk through fishing and habitat loss
Governments are being urged to agree measures for protecting open ocean and sea floor habitats at a major United Nations conservation meeting in Bonn.
Argentina and Brazil are among the countries objecting to proposals put forward at the Convention on Biological Diversity (CBD) meeting.
Scientists advising the CBD believe more protection is vital for marine areas outside national jurisdiction.
The CBD is the UN agreement intended to slow the loss of the Earth's species.
Its key target is to halt and begin to reverse the global decline by 2010, a target that many observers believe cannot be met.
The rate of species extinctions is estimated to be between 100 and 1,000 times the rate it would be without human impacts such as loss of habitat, climate change and overfishing, and some marine ecosystems remote from land are showing signs of degradation.
"Increasing attention has been brought to the fact that many marine species including commercially important ones have been brought to the edge of collapse," said Jacqueline McGlade, executive director of the European Environment Agency (EEA), the EU's environmental research and advisory body.
"The last 18 months have brought a huge body of evidence showing how vulnerable the ocean is to depletion and climate change," she told BBC News from the meeting in Germany.
Among that evidence is a major recent study concluding that if current trends continue, there will be no commercially viable marine fisheries by 2050.
Against this background, the CBD's advisors proposed a raft of measures aimed at researching and protecting the oceans and the life within them.
They include taking a series of steps towards establishing marine reserves in international waters.
These areas, which make up the vast majority of the oceans, are partly regulated by Regional Fisheries Management Organisations (RFMOs).
But these are basically there to manage fishing, not to pursue a wider conservation agenda - and the environmental record of some is so poor that critics have labelled them "mis-management organisations".
Bottom trawlers rip coral from the ocean floor, which is discarded
The EEA says nations' objections to the measures do not mean they are opposed in principle to greater open ocean protection.
Rather, it says, they question whether the CBD is the right organisation to make decisions in this field, preferring to work through the UN Convention on the Law of the Sea (Unclos).
Such a dispute may appear arcane, but can have important consequences.
Last year, Japan objected to plans to protect fish species under the Convention on International Trade in Endangered Species (Cites), arguing that the Food and Agriculture Organization (FAO) is the more appropriate body.
Governments generally send environment officials to Cites, but farming and fisheries officials to the FAO; and different priorities may be displayed by the two groups.
Professor McGlade is anxious that if the root of the current dispute is procedural, it should not prevent the adoption of measures that could prove vital to the long-term health of ocean ecosystems and the food that flows from them.
"It would be pitiful if we lost this opportunity for procedural reasons," she said.
The Brazilian and Argentinian delegations at the CBD could not be reached for comment.