As the international agency controlling fishing for 30 migratory species in the Atlantic Ocean, the International Commission for the Conservation of Atlantic Tunas (ICCAT) has a vital ecological role. From the spawning waters of the Gulf of Mexico, up across the feeding grounds of the North Atlantic and into stock-rich regions of the Mediterranean, ICCAT decisions on allowable commercial catches can have a huge environmental impact. They affect target species, such as bluefin tuna or swordfish, creatures ensnared as bycatch — notably sharks or dolphins — and their food webs.

Timely, proper assessments of the stocks of specific species, analysis of the age and size of captured fish, and understanding of the effect of years of overfishing should be integral components of ICCAT deliberations. These should lead to science-based management decisions on the economically important and culturally rich resources under the stewardship of the Madrid-based agency. They don't.

Disturbingly, the media and the public are blocked from observing ICCAT discussions. Only in recent years did ICCAT allow some non-governmental organizations to attend its conferences, but even they must pay an ‘observer fee’ of at least US$500, a move clearly designed to limit access.

Officials at the US National Marine Fisheries estimate that US taxpayers contributed some $250,000 to host ICCAT's meeting in New Orleans last month, which included representatives of 23 non-member fishing nations. Deliberations — funded by the taxpayers of the respective nations — affect the international public's resources. Given this public funding, such meetings should be open, but, apart from a press conference at the start, reporters were barred.

What do ICCAT members have to hide? Shamefully, representatives of the major markets in Asia and the heaviest fishing nations in Europe choose to meet in private and put their economic interests ahead of science-based management. This is what happened in New Orleans (see Nature 432, 539; 2004doi:10.1038/432539a).

One ICCAT delegate suggested that the reason the press was not allowed in was because this would disturb developing nations. Excuses like this show the lengths to which officials will go to keep proceedings under wraps.

Transparency is essential if we are to understand what is happening to ocean resources. The Convention on Biological Diversity operates in such a manner. ICCAT should follow its example, starting by opening up its next meeting in Japan in April.