Icelandic whaling boats have left port to begin the 2015 whaling season, authorities said on Monday as more than 700,000 people signed a petition calling for an end to the hunt.

Two whaling boats, Hvalur 8 and Hvalur 9, "left yesterday" (Sunday), Gunnlaugur Gunnlaugsson, the manager of the Hvalfjordur whaling station, told AFP.

No whales had been caught as of Monday afternoon.

Iceland and Norway are the only nations that openly defy the International Whaling Commission's 1986 ban on hunting whales.

For 2015, Iceland's fisheries ministry has given the whalers a quota of 154 fin whales -- the second largest mammal after the blue whale -- and 229 minke whales.

Last year they killed 137 fin whales and 24 minkes.

A petition against the hunt on the activist website Avaaz.org had by Monday afternoon gathered more than 700,000 signatures -- equivalent to more than twice the population of Iceland.

The petition calls on the government of the Caribbean nation St Kitts and Nevis to withdraw its flag from the Icelandic whaling company Hvalur's vessel Winter Bay, so that it cannot deliver a shipment of whale meat that is currently on its way to Japan.

Consumption of whale meat in Japan has fallen sharply in recent years, while polls indicate that few Icelanders regularly eat the meat.