Diving Otters
Killer whale. Photo by Gerald and Buff Corsi © California Academy of Sciences.
DB: This is Earth and Sky with a sea otter scientific whodunit.
JB: James Estes is a research scientist with the U.S. Geological Survey in Santa Cruz, California. Since the 1970s, he’s been part of an ongoing project to study sea otters and kelp forest ecosystems along the Alaska coast. In the 1990s, otter populations took a nose dive. Now Estes is trying to find out what’s killing the otters.
DB: Using a small skiff to travels in coastal waters, he found no trace of disease, reproductive failure, or famine. But he did discover one curious lagoon where otters once flourished. Beginning in the 1990s, researchers noticed something that hadn’t been seen before – killer whales attacking sea otters.
James Estes: So that was a mind-blower for us… Prior to 1990 we’d never seen a killer whale eat a sea otter…. We began seeing more killer whales in the coastal zone, and when we started doing a bunch of analysis of the actual data that we had, that became the most obvious and reasonable explanation for what had happened.
JB: Killer whales have been known to feed on seals and sea lions. It’s possible that, as these creatures have become less abundant, the whales might have switched to sea otters. Thanks today to the U.S. Forest Service and to the National Fish and Wildlife Foundation – supporting the conservation of native fish, wildlife, plants and their habitats. We’re Block and Byrd for Earth and Sky.
The following individual was interviewed for today’s show. Our thanks to:
James A. Estes, Ph.D.
Research Biologist
Western Ecological Research Center
U.S. Geological Survey
Santa Cruz, CA USA
Additional Teacher Resources
U.S. Geological Survey, News Releases: USGS Finds Sea Otters at Risk From Killer Whales In a Changing Ocean
Because of a lack of Steller sea lions and harbor seals, large numbers of sea otters are being eaten by hungry killer whales in western Alaska waters. This report discusses the consequences and repercussions of the addition of predators to the sea otter populations, and the future of the ecosystems in which they live.
Science News for Kids: Sea Otters, Kelp, and Killer Whales
This article discusses the sea otters role as a keystone species within its ecosystem, and how it came to be that killer whales began to eat them. The article then deals with how the National Oceanic and Atmospheric Administration is working to find out what new threats otters face. The research is hoped to shape a new plan to help otter populations thrive.
U.S. Geological Survey, Biology: Sea Otters in the North Pacific Ocean
This site provides an informative natural history of the sea otter in the north Pacific Ocean. From central Baja California, north and west along the Pacific Rim to the Kamchatika Peninsula in Russia, to south along the Kuril Islands of northern Japan. The primary area of focus is the recovery of the otter population from mass depletion due to hunting and its effect of the ecosystems of the north Pacific Ocean.
U.S. Geological Survey, Western Ecological Research Center: Sea Otter Research at WERC
Sea otters are keystone predators in the nearshore environment of the eastern Pacific Ocean, in a food web composed of sea otter, sea urchin, and kelp forest. Without sea otters, the kelp forest can be overgrazed by sea urchins, which in turn can affect other species that depend on this ecosystem. This report explains the role of the keystone species in this ecosystem.
Defenders of Wildlife, Sea Otters: Conserving Sea Otter Populations Worldwide
This site is a great resource for finding information about sea otter species, their population status, distribution, and importance in the ecosystems in which they inhabit. The site also provides a myriad of links on sea otter species, fact sheets, and conservation organizations.
