Free Newsletters - Space - Defense - Environment - Energy - Solar - Nuclear
..
. Earth Science News .




WATER WORLD
White shark diets vary with age and among individuals
by Staff Writers
Santa Cruz CA (SPX) Oct 03, 2012


File image.

White sharks, the largest predatory sharks in the ocean, are thought of as apex predators that feed primarily on seals and sea lions. But a new study by researchers at the University of California, Santa Cruz, shows surprising variability in the dietary preferences of individual sharks.

The researchers described their findings in a paper published online September 28 in PLoS ONE. They analyzed the composition of growth bands in shark vertebrae to trace variations in diet over a shark's lifetime. Stable isotopes of carbon and nitrogen incorporated into an animal's tissues serve as a natural tracer of dietary inputs.

"We did find that white shark diets changed with age, as expected, but we were surprised that the patterns and extent of change differed among individuals," said Sora Kim, who led the study as a UCSC graduate student and is now at the University of Wyoming.

The researchers analyzed vertebrae of 15 adult white sharks that had been caught along the west coast (14 off California and one off Baja California). Sharks in this population consume a wide range of prey, including seals, sea lions, dolphins, fish, and squid. But not every shark eats the same mix of prey, said coauthor Paul Koch, professor of Earth and planetary sciences at UCSC.

"We confirmed that the diets of many individuals observed at seal and sea lion rookeries shift from fish to marine mammals as the sharks mature," he said.

"In addition, we discovered that different individual sharks may specialize on different types of prey. These two types of flexibility in feeding behavior are difficult to document using traditional methods, but may be very important for understanding how the population is supported by the eastern Pacific ecosystem and how it may respond to changes in that ecosystem."

Tagging studies have shown that the white sharks found along the California coast have a regular migratory pattern, cruising coastal sites from late summer to early winter and moving to offshore areas during the rest of the year.

While sharks within this population may have predictable movement patterns, the new study shows that there are important dietary and behavioral differences among individual sharks.

The study relied on vertebrae obtained from white shark specimens in various collections. The sharks had been caught at different times and places along the coast from 1957 to 2000. "Interestingly, we do see a small shift in diet as marine mammal populations increased after the passage of the Marine Mammal Protection Act in 1972," Kim said.

In addition to Kim and Koch, the coauthors of the paper include James Estes, professor of ecology and evolutionary biology at UCSC, and Tim Tinker, a biologist with the U.S. Geological Survey and adjunct professor of ecology and evolutionary biology at UCSC. This research was funded by the National Science Foundation (NSF-OCE 0345943 and NSF-EAR 1053013).

.


Related Links
University of California - Santa Cruz
Water News - Science, Technology and Politics






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





WATER WORLD
Great Barrier Reef loosing coral
Sydney (UPI) Oct 2, 2012
Half of the Great Barrier Reef's coral has been wiped out in the last 27 years, a new study says. If the mass die-off continues, the study warns, less than 25 percent of the coral cover would exist in 2022. Published Tuesday in the Proceedings of the National Academy of Sciences, the study was conducted by researchers from the Australian Institute of Marine Science and the Univer ... read more


WATER WORLD
Hong Kong seeks answers after deadly ferry crash

18 school children buried in China landslide

World facing unprecedented refugee crisis: UNHCR

Twenty-five killed in Hong Kong ferry collision: official

WATER WORLD
HP stock sinks with slow turnaround

Malaysia hearing on Australia rare earths plant postponed

Ancient stinging nettles reveal Bronze Age trade connections

Probing the mysteries of cracks and stresses

WATER WORLD
Now in Science: It's not too late for troubled fisheries

White shark diets vary with age and among individuals

Australia admits neglect of Great Barrier Reef

New clues about ancient water cycles shed light on US deserts

WATER WORLD
Australian tycoon fined for Arctic party cruise

Study: Arctic warming faster than before

Rudolph unfed loathes rain, dear

Melting Arctic ice cap at record low

WATER WORLD
Mother of cultivated rice came from China's Pearl River

Sandia probability maps help sniff out food contamination

An Old Pest Reemerges in Organic Orchards

Bhutan aims to be first 100% organic nation

WATER WORLD
Typhoon Maliksi nearing Japan's northeast

Nigeria seasonal floods kill 148: Red Cross

Powerful typhoon hits Japan mainland

Typhoon Jelawat on course to hit mainland Japan

WATER WORLD
Nigeria seeks to end the curse of unfinished projects

Ivory Coast opens first major trial of soldiers in political crisis

France to facilitate Mali anti-rebel force

One-third of Lesotho faces food crisis: UN food agency

WATER WORLD
Compelling evidence that brain parts evolve independently

Anti-aging pill being developed

Human Brains Develop Wiring Slowly, Differing from Chimpanzees

Breaking up harder to do on Facebook




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement