Whaling opponents held a "national day of action" Saturday in more than 20 coastal communities around Australia to protest Japanese hunting of humpbacks and other whales that annually migrate to Australian waters.

The environmentalists and whale watching enthusiasts denounced Japan's scientific whaling program as a "sham" and held a minute of silence for the more than 500 whales killed in the latest hunt in Antarctic waters, which ended in February.

The protest coincided with the start of the annual migration of humpback whales along Australia's coasts. Japan recently decided to extend the whaling program later this year to include 50 humpback whales, which are classified as "vulnerable" on the Red List maintained by the International Union for the Conservation of Nature.

According to the International Fund for Animal Welfare, which helped organize the protest, Australia's whale watching industry is booming, generating some 300 million Australian dollars for the economy each year.

The environmentalists want the Australian government to launch legal action against Japan to end what they see as commercial whaling in disguise, instead of just taking its case to the International Whaling Commission, which is due to meet May 28 to 31 in Alaska.

Earlier this month, a panel of Australian experts on international law commissioned by the International Fund for Animal Welfare concluded that Japanese whaling breaches the U.N. Convention on the Law of the Sea, the Antarctic Treaty System, the Convention on International Trade in Endangered Species and the International Convention on the Regulation of Whaling.