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:10/16/2014)... be cultivated efficiently, they are anything but sustainable: ... monoculture cultivation is becoming increasingly evident. Despite their ... and are regarded as the sole possibility of ... wrongfully, finds Bernhard Schmid, an ecology professor at ... form of agriculture and forestry. After all, a ...
(Date:10/15/2014)... PORT WASHINGTON, N.Y. , Oct. 15, 2014 ... in technology solutions for home and community-based care, ... the benefits of implementing Sandata,s Santrax® Electronic Visit ... Quality Care Services is a home health company ... Texas . ...
(Date:10/15/2014)... spreading rapidly and to an unexpected extent. The outbreak ... and the virus shows a new disease dynamic in ... this reason, the German National Academy of Sciences Leopoldina, ... and the Union of the German Academies of Sciences ... epidemic today. , In the statement the academies call ...
Breaking Biology News(10 mins):Plant communities produce greater yield than monocultures 2Plant communities produce greater yield than monocultures 3Sandata Announces Case Study with Quality Care Services, Inc. 2Academies call for consequences from the Ebola virus epidemic 2Academies call for consequences from the Ebola virus epidemic 3Academies call for consequences from the Ebola virus epidemic 4Academies call for consequences from the Ebola virus epidemic 5
(Date:10/22/2014)... 22, 2014 Grace Century, a private ... projects, announces the addition of Dr. Yousef “Josh” ... advisory team. Dr. Siddiqui will provide further healthcare expertise ... graduate of University College Medical School in ... medicine in 2001. With further certification as a General ...
(Date:10/22/2014)... , Oct. 22, 2014 /PRNewswire/ - iCo Therapeutics ("iCo" ... announced next steps for its Oral Amphotericin B ... its in vitro work involving samples ... now plans to complete pre clinical studies and ... Phase 1A clinical trial, utilizing approximately $700,000 of ...
(Date:10/20/2014)... (PRWEB) October 20, 2014 The ... (Medication Dispensing Systems, Packaging and Labeling Systems, Table-top ... Automation) - Global Forecasts & Trends to 2019” ... and opportunities in North America, Europe, Asia-Pacific, and ... 101 market tables and 30 figures spread through ...
(Date:10/20/2014)... /PRNewswire/ - BIOREM Inc. (TSXV: BRM) ("Biorem" or "the Company") today ... to $5.8 million and provides a good start to Q4.  The ... America and one in the Middle East ... record levels," said Peter Bruijns , President & CEO. "Total ... Q3 than they have been for any complete year since the ...
Breaking Biology Technology:Dr. Yousef Siddiqui joins the Grace Century Advisory Team 2iCo Therapeutics Announces Advancement of Oral Amphotericin B Program 2iCo Therapeutics Announces Advancement of Oral Amphotericin B Program 3Pharmacy Automation Systems Market worth $4,566.2 Million by 2019 - New Research Report by MarketsandMarkets 2Pharmacy Automation Systems Market worth $4,566.2 Million by 2019 - New Research Report by MarketsandMarkets 3Pharmacy Automation Systems Market worth $4,566.2 Million by 2019 - New Research Report by MarketsandMarkets 4
Cached News: