HOME >> BIOLOGY >> NEWS
Killer Whales Have Begun Preying On Sea Otters, Causing Disruption Of Coastal Ecosystems In Western Alaska

ported by several lines of evidence, Estes said. First is the sudden increase in observed attacks. A careful statistical analysis found it extremely unlikely that the cluster of recent observations was due to chance alone.

The researchers also compared sea otter populations at two sites on Adak Island, one an open bay and the other an area inaccessible to killer whales. From 1993 through 1997, sea otter numbers were stable in the protected Clam Lagoon, while in the adjacent Kuluk Bay they declined by 76 percent.

According to calculations based on the team's observations in one section of the Aleutian Islands, killer whales must have killed 6,788 sea otters per year between 1991 and 1997 to account for the observed decline in the population. Taking into account the number of hours of field observations by the research team during this period, the number of those attacks they could expect to have observed is 5.05, which is very close to the actual number of six observed attacks.

The researchers ruled out other possible causes of the sea otter decline, such as disease, toxins, and starvation, Estes said.

"It took about two years for me to become convinced that killer whales were responsible, as we dismissed one possibility after another and gradually gathered direct evidence pointing to killer whales," Estes said.

Terrie Williams, an associate professor of biology at UCSC and coauthor of the paper, analyzed the caloric value of sea otters, which are a less nutritious food source than killer whales' usual prey because they have very little blubber. Williams estimated that a single killer whale would need to eat 1,825 otters per year to meet its energy requirements. These figures suggest that as few as four killer whales feeding exclusively on sea otters could have driven the population decline observed over a large area of the Aleutian archipelago.

Sea otters were nearly extinct by the early 20th century due to overhunting for the fur trade. Pr
'"/>

Contact: Tim Stephens
stephens@cats.ucsc.edu
831-459-2495
University of California - Santa Cruz
15-Oct-1998


Page: 1 2 3 4

Related biology news :

1. Killer virus
2. Tracking A Killers Progression
3. USGS Finds Sea Otters At Risk From Killer Whales In A Changing Ocean
4. French Researchers Breed Flightless Ladybirds As Pest-Killers
5. University Of Kentucky Researcher Awarded MERIT Extension For Study Of Third World Killer
6. How A Common Protein Becomes A Cancer Killer
7. Weevils Wipe Out Killer Weeds In Papua New Guinea
8. Virginia Tech Scientists Study Killer Molecules
9. Whales, seals or men? Who stole all the fish?
10. Whales get the bends
11. Whales drawn to waters off Mississippi River Delta

Post Your Comments:
(Date:8/27/2014)... DURHAM, N.C. -- When we want to listen carefully ... talking. The second thing we do is stop moving ... unwanted sounds generated by our own movements. , This ... deep in the brain. Indeed, indirect evidence has long ... somehow influences the auditory cortex, which gives rise to ...
(Date:8/27/2014)... release is available in German . ... is the most common inherited disease affecting the peripheral ... the Max Planck Institute of Experimental Medicine and University ... Schwann cells is impaired in rats with the disease. ... layer known as myelin, which facilitates the rapid transfer ...
(Date:8/27/2014)... fishing traps are lost or abandoned each year in ... traps, which continue to catch fish, crabs, and other ... to habitat, fisheries, and the watermen who depend on ... newly published NOAA study. , The report, published in ... of its kind to examine the derelict fish trap ...
Breaking Biology News(10 mins):Stop and listen: Study shows how movement affects hearing 2Stop and listen: Study shows how movement affects hearing 3Potential therapy for incurable Charcot-Marie-Tooth disease 2NOAA's Marine Debris Program reports on the national issue of derelict fishing traps 2
(Date:8/27/2014)... 27, 2014 Rhythm, a biopharmaceutical company developing ... that result in metabolic disorders, announced today that it ... the U.S. Securities and Exchange Commission (SEC) relating to ... common stock. The number of shares to be offered ... yet been determined. Citigroup and Cowen and ...
(Date:8/27/2014)...   MSC , a healthcare performance improvement company ... appointment of Mary Beth Loesch to President ... experience preparing companies for rapid growth and market expansion, ... of Corporate Development and Healthcare. In that role, she ... well as corporate strategy and marketing. Previously, Loesch served ...
(Date:8/27/2014)... , Aug. 27, 2014 Reportlinker.com announces ... in its catalogue: Global Chelating Agents ... About Chelating Agent A chelating agent ... bonds with metal ions, thereby forming a metal-ion ... metal-ions have on chemical processes, formulations, and the ...
(Date:8/27/2014)... MADISON, N.J. , Aug. 27, 2014 /PRNewswire/ ... significant potential to help physicians better identify early-stage ... progression and disability, according to a new study ... from Quest Diagnostics (NYSE: DGX ) ... of the 14-3-3eta protein outperformed conventional antibody-serum testing, ...
Breaking Biology Technology:Rhythm Files Registration Statement for Proposed Initial Public Offering 2MSC names Mary Beth Loesch President and CEO 2Global Chelating Agents Market 2014-2018 2Global Chelating Agents Market 2014-2018 3Global Chelating Agents Market 2014-2018 4Novel Biomarker Detects Early Rheumatoid Arthritis Better than Conventional Methods Alone, According to Journal of Rheumatology Study 2Novel Biomarker Detects Early Rheumatoid Arthritis Better than Conventional Methods Alone, According to Journal of Rheumatology Study 3Novel Biomarker Detects Early Rheumatoid Arthritis Better than Conventional Methods Alone, According to Journal of Rheumatology Study 4
Cached News: