WASHINGTON: Whales have a powerful and positive influence on the function of oceans, global carbon storage, and the health of commercial fisheries, a new study suggests."For a long time, whales have been considered too rare to make much of a difference in the oceans," said University of Vermont conservation biologist Joe Roman.Roman and a team of biologists, who tallied several decades of research on whales from around the world, have found that whales, in fact, make a huge difference.They have a powerful and positive influence on the function of oceans, global carbon storage, and the health of commercial fisheries, they said."The decline in great whale numbers estimated to be at least 66 per cent and perhaps as high as 90 per cent, has likely altered the structure and function of the oceans, but recovery is possible and in many cases is already underway," Roman and his colleagues wrote in the journal Frontiers in Ecology and the Environment."The continued recovery of great whales may help to buffer marine ecosystems from destabilising stresses," the researchers wrote.This recovered role may be especially important as climate change threatens ocean ecosystems with rising temperatures and acidification."As long-lived species, they enhance the predictability and stability of marine ecosystems," Roman said.Baleen and sperm whales, known collectively as the "great whales," include the largest animals to have ever lived on Earth.With huge metabolic demands — and large populations before humans started hunting them - great whales are the ocean's ecosystem engineers: they eat many fish and invertebrates, are themselves prey to other predators like killer whales, and distribute nutrients through the water.Even their carcasses, dropping to the seafloor, provide habitat for many species that only exist on these "whale falls." Commercial whaling dramatically reduced the biomass and abundance of great whales."As humpbacks, grey whales, sperm whales and other cetaceans recover from centuries of over-hunting, we are beginning to see that they also play an important role in the ocean," Roman said.