The 175-nation Convention on International Trade in Endangered Species, or CITES, will be discussing new proposals to regulate the shark trade and a ban on the export of Atlantic bluefin, a tuna species prized by sushi lovers.
There are 42 proposals on the table at the conference, addressing a range of issues from combating elephant poaching for ivory in Africa to banning trade in polar bear skins. But those focusing on sharks and tuna are likely to be among the most contentious.
They pit the Europeans and Americans against fishing nations in North Africa and Asia, especially Japan, which has already vowed to ignore any bluefin ban. A bid to regulate the trade in red and pink corals - harvested to make expensive jewelry - could also divide the delegates.
CITES Secretary-General Willem Wijnstekers told The Associated Press this week that countries were turning to his organization because existing management tools were not working and that many of the ocean's commercially fished species were under threat. He also said there was much more support than two years ago for restricting or banning the trade of many marine species, including the Atlantic bluefin.
"I don't think anyone has an argument against the listing of Atlantic bluefin tuna," said Wijnstekers, whose organization has come out in support of the export ban. "There is no scientific argument against that."
According to the U.N. Food and Agriculture Organization, more than half of all marine fish stocks are under threat.
Monaco - the sponsor of the proposed ban on the export of Atlantic bluefin tuna - says numbers have fallen by nearly 75 percent since 1957. But most of the decline has occurred over the last decade with demand driven by sushi lovers in Japan and elsewhere for the bluefin' succulent red and pink meat.
The United States backed the ban proposal last week. Many European countries also expressed support, although France and the European Commission have endorsed a compromise to delay the ban until 2011.
Japan, which consumes 80 percent of Atlantic bluefin eaten worldwide, has said it will ignore the ban. The more critical issue is whether other key fishing countries will join Japan's rebuff - which would allow them to sell tuna to Japan.
Tokyo also argues that concerns about the extinction of the Atlantic bluefin are overblown.
The threat of a ban has some Japanese warning their culture is under siege. Sushi is an iconic dish in Japan, where fatty bluefin - called "o-toro" in Japan - sells for as much as 2,000 yen ($20) a piece in high-end Tokyo restaurants.
The conference in Doha is also expected to discuss ways to tackle the illegal trade of tiger products, and the protection of less-known species such as the spiny-tailed iguanas of Mexico and Central America and the spectacular Dynastes satanas beetle of Latin America - both prized by collectors.
Achim Steiner, the executive director of the United Nations Environment Program, which administers the CITES, said limiting the trade on a range of threatened species could go a long way to ensuring biodiversity.
"By ensuring that the international trade in wildlife is properly regulated, CITES can assist in conserving the planet's wild fauna and flora from overexploitation and contribute to the sustainable development," Steiner said.