Killer whales may be the top of the food chain underwater, but they stand little chance against the eco-tourists who try to catch a glimpse of the majestic mammals rising above the water line.

"We now have more whale-watch boats than there are whales," said Kelley Balcomb-Bartok of the Orca Conservancy, a nonprofit organization in Washington state that works with scientists to protect Orcas.

All this activity is raising concerns about the whales' health and survival.

Some scientists say noise from all the boat traffic may impair a whale's sonar ability as much as 95 percent. The whales need sonar to find food.

Three new studies released this month suggest the interference is damaging the whales, whose population in the Puget Sound region has fallen from 98 to 80 in less than a decade.

Scientists say all the traffic also forces the Orcas to move around more, wasting energy needed for hunting food.

"I would say that at times when there are a lot of boats and there is a lot of noise, that they are irritated,"said Tom McMillen, captain of the whale-watching boat Stellar Sea, which takes out three groups a day.

Scientists say the noise from the boats leads to added stress on the animals, which are already coping with fewer salmon to eat and increasing pollution.

(Agencies)