This raised concerns among some environmental groups such as Greenpeace, fearing it could add fuel to the Japanese wish of continuing its annual cull. In contrast to his stance on the minke whale quota, Flannery has expressed relief over the dumping of the quota of the rarer humpback whale, and further was worried how whales were slaughtered, wishing them to be "killed as humanely as possible". Flannery suggested that krill and other small crustaceans, the primary food source for many large whales and an essential part of the marine food chain, were of greater concern than the Japanese whaling.