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:
*Name:
*Comment:
*Email:


(Date:3/10/2016)... 10, 2016   Unisys Corporation (NYSE: UIS ... (CBP) is testing its biometric identity solution at the ... to help identify certain non-U.S. citizens leaving the country. ... designed to help determine the efficiency and accuracy of using ... and will run until May 2016. --> ...
(Date:3/9/2016)... 9, 2016 Nigeria ... more than 23,000 public service employees either did not ... their salary unlawfully.    --> Nigeria ... that more than 23,000 public service employees either did ... receiving their salary unlawfully.    --> DERMALOG, ...
(Date:3/8/2016)... N.C. , March 8, 2016   ... sensor technology, today announced it has secured $11M ... by GII Tech, a new venture fund being ... with additional participation from existing investors TDF Ventures ... the funds to continue its triple-digit growth and ...
Breaking Biology News(10 mins):
(Date:4/29/2016)... (PRWEB) , ... April 30, 2016 , ... The MIT ... textile design, the bioLogic team explored how bacterial properties can be applied to fabric ... using Natto bacteria, which move in response to humidity change. The team harvested Natto ...
(Date:4/29/2016)... ... April 29, 2016 , ... Summit for Stem Cell has received ... of a patient-specific stem cell therapy for the treatment of Parkinson’s disease. The Summit ... Loring at The Scripps Research Institute in San Diego, CA. , The ...
(Date:4/28/2016)... ... April 28, 2016 , ... Connecticut Innovations ... companies, today announced the launch of VentureClash , a $5 million global ... , “VentureClash looks to attract the best early-stage companies here in Connecticut, around ...
(Date:4/27/2016)... ... 27, 2016 , ... Shimadzu Scientific Instruments (SSI) will be ... Business Conference and Expo. Shimadzu’s high-performance instruments enable laboratories to test cannabis products ... can stop by booth 1021 to learn how Shimadzu’s instruments can help improve ...
Breaking Biology Technology:
Cached News: