Featured Research

from universities, journals, and other organizations

Declining sea ice strands baby harp seals

Date:
July 22, 2013
Source:
Duke University
Summary:
Young harp seals off the eastern coast of Canada are at much higher risk of getting stranded than adult seals because of shrinking sea ice cover caused by recent warming in the North Atlantic, according to a Duke University study.

Dwindling sea ice is leaving vulnerable baby harp seals stranded in greater numbers, according to an analysis by the Duke Marine Lab and the International Fund for Animal Welfare.
Credit: Courtesy of IFAW

Young harp seals off the eastern coast of Canada are at much higher risk of getting stranded than adult seals because of shrinking sea ice cover caused by recent warming in the North Atlantic, according to a Duke University study.

"Stranding rates for the region's adult seals have generally not gone up as sea ice cover has declined; it's the young-of-the-year animals who are stranding (those less than one year old)," said David Johnston, a research scientist at Duke's Nicholas School of the Environment.

"And it's not just the weakest pups -- those with low genetic diversity and presumably lower ability to adapt to environmental changes -- that are stranding," he said. "It appears genetic fitness has little effect on this."

The study, published online this week in the peer-reviewed open-access journal PLoS One, is the first to gauge the relative roles that genetic, environmental and demographic factors such as age and gender may be playing in harp seal stranding rates along the U.S. and Canadian east coasts in recent years.

Harp seals rely on stable winter sea ice as safe platforms to give birth and nurse their young until the pups can swim, hunt and fend off predators for themselves. In years of extremely light ice cover, entire year-classes may be disappearing from the population, Johnston said.

The new study complements a Duke-led study published last year that found seasonal sea ice cover in all four harp seal breeding regions in the North Atlantic has declined by up to 6 percent a decade since 1979, when satellite records of ice conditions in the region began.

To expand upon the earlier study, Johnston and four colleagues at the Duke University Marine Lab compared images of winter ice from 1992 to 2010 in a major whelping region off Canada's east coast, the Gulf of St. Lawrence, with yearly reports of dead harp seal strandings along the U.S. northeast coast that were grouped by gender and estimated age of the seal.

The analysis revealed a significant difference: In years when ice cover was reduced, stranding rates for younger seals rose sharply, even though stranding rates for adult seals remained relatively stable.

The researchers also compared DNA samples from 106 harp seals that had been stranded ashore with those from seals that had accidentally been caught by fishing boats in the region during the same period.

"We used measures of genetic diversity to determine if the dead seals that came ashore were less fit than the presumably healthy ones that had been caught by fishermen, but found no difference," said Thomas Schultz, director of Duke's Marine Conservation Molecular Facility. "The stranded animals appear to have come from a genetically diverse population, and we have no evidence to suggest that genetic fitness played a role in their deaths."

The analysis also showed that male seals stranded more frequently than females during the study period, and that this relationship was strongest during light ice years.

"Our findings demonstrate that sea ice cover and demographic factors have a greater influence on harp seal stranding rates than genetic diversity," said Brianne Soulen, who co-led the study while she was a master's degree student in marine ecology at Duke.

Kristina Cammen, a Duke Ph.D. student who also co-led the study, said the findings "provide more context for what we're seeing in high-latitude species in general. The effects of climate change are acting on younger animals; it's affecting them during the crucial first part of their life."


Story Source:

The above story is based on materials provided by Duke University. Note: Materials may be edited for content and length.


Journal Reference:

  1. Brianne K. Soulen, Kristina Cammen, Thomas F. Schultz, David W. Johnston. Factors Affecting Harp Seal (Pagophilus groenlandicus) Strandings in the Northwest Atlantic. PLoS ONE, 2013; 8 (7): e68779 DOI: 10.1371/journal.pone.0068779

Cite This Page:

Duke University. "Declining sea ice strands baby harp seals." ScienceDaily. ScienceDaily, 22 July 2013. <www.sciencedaily.com/releases/2013/07/130722123124.htm>.
Duke University. (2013, July 22). Declining sea ice strands baby harp seals. ScienceDaily. Retrieved August 1, 2014 from www.sciencedaily.com/releases/2013/07/130722123124.htm
Duke University. "Declining sea ice strands baby harp seals." ScienceDaily. www.sciencedaily.com/releases/2013/07/130722123124.htm (accessed August 1, 2014).

Share This




More Earth & Climate News

Friday, August 1, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Visitors Feel Part of the Pack at Wolf Preserve

Visitors Feel Part of the Pack at Wolf Preserve

AP (July 31, 2014) Seacrest Wolf Preserve on the northern Florida panhandle allows more than 10,000 visitors each year to get up close and personal with Arctic and British Columbian Wolves. (July 31) Video provided by AP
Powered by NewsLook.com
Florida Panther Rebound Upsets Ranchers

Florida Panther Rebound Upsets Ranchers

AP (July 31, 2014) With Florida's panther population rebounding, some ranchers complain the protected predators are once again killing their calves. (July 31) Video provided by AP
Powered by NewsLook.com
Big Waves In Arctic Ocean Threaten Polar Ice

Big Waves In Arctic Ocean Threaten Polar Ice

Newsy (July 30, 2014) Big waves in parts of the Arctic Ocean are unprecedented, mainly because they used to be covered in ice. Video provided by Newsy
Powered by NewsLook.com
Raw: Thousands Flocking to German Crop Circle

Raw: Thousands Flocking to German Crop Circle

AP (July 30, 2014) Thousands of people are trekking to a Bavarian farmer's field to check out a mysterious set of crop circles. (July 30) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins