By Helen Briggs
BBC News science reporter
What are the key issues being discussed at the annual meeting of the International Whaling Commission (IWC) in Ulsan, South Korea?
WHALING SINCE THE BAN
Japan, Norway and Iceland have killed more than 25,000 whales since the IWC moratorium took effect in 1986
Most whales are killed with harpoons designed to explode inside them, though small traditional coastal communities use other methods
Whalers say unconsciousness or death is near instantaneous; opponents say some whales can take over an hour to die
What is the IWC and what does it do?
The IWC is the worldwide regulatory body for whaling. It was set up after World War II to regulate the whale hunting industry.
In 1982, with many whale populations close to extinction, it agreed to implement a ban, "the moratorium" on commercial whaling, which came into effect in 1986. Its dual mandate of both managing whaling and conserving whales has led to bitter struggles over the years between the whaling nations - Japan, Norway and Iceland - and their opponents.
What has happened since the ban was put in place?
Conservationists say the ban has largely been successful. Some, but by no means all, species are slowly recovering. Despite the ban, some nations still carry out whaling. Norway has continued to kill minke whales in the North Atlantic since 1993 through a legal objection lodged against the moratorium on commercial whaling.
Japan and Iceland also continue to kill whales, for what it calls scientific purposes. Japan catches about 500 minke whales a year, as well as 10 sperm whales, 50 Bryde's whales and 100 sei whales.
Japan wants to double the number of whales killed and to include two new species in its annual Antarctic cull. Australia is leading a protest against the plans, backed by Britain the US and New Zealand.
What will be the main sticking point this year?
The main issue, again, is whether whale stocks have recovered enough to lift the ban on commercial whaling in a controlled fashion. At last year's meeting in Sorrento, Italy, the commission moved closer to agreeing new rules that would allow this to take place.
At the heart of the matter is the Revised Management Scheme - basically a scientifically sound way to set catch limits for more abundant species. But anti-whalers fear that if the scheme were adopted it would lead to a "free-for-all" on all stocks of all whales species and an end to the moratorium.
Are their fears justified?
It depends on who you believe. Anti-whaling groups say the ban on commercial whaling is under threat as never before. They say this meeting promises to be unlike any other because for the first time since commercial whaling was banned, pro-whaling countries may hold the majority of votes.
The whaling nations continue to insist stocks are now sufficiently strong among some species to permit a sustainable commercial hunt to go ahead. Countries such as Japan say whale meat has been part of their diet for thousands of years and other nations should respect their traditions.
Japan is threatening to pull out of the commission and join forces with other whaling countries unless it is allowed to carry out limited hunting for commercial purposes.
The 57th annual meeting of the IWC began at the end of May, and has proceeded with a series of scientific meetings. The open sessions begin on Monday 20 June. The meeting is being attended by thousands of official delegates, scientists, NGO representatives and the media.