Navigation Links
Unveiling the underwater ways of the white shark
Date:2/18/2008

It's hard to study a creature when you only catch fleeting glimpses of it. Up until recently, that was one of the big stumbling blocks for marine biologists and ecologists, but advances in electronic tracking technology have allowed them to peer farther across, and deeper under, the surface of the oceans than ever before.

Satellite tracking systems and acoustic sensors are giving researchers insights into the behavior and lifestyles of some very elusive animals in the ocean, including the fabled white shark.

Researchers from several institutions, including Stanford University, have joined their efforts in a Census of Marine Life project called Tagging of Pacific Predators (TOPP). Since the project began in 1999, they have attached more than 3,000 tags to sharks, seals, whales, tunas, squids, turtles, albatross and more. For the first time, these TOPP researchers are getting a glimpse of a pelagic ecosystem from the California Current to the North Pacific at daily, seasonal and yearly time scales.

Along with the white shark, the TOPP researchers also have been studying the routes and habits of two cousins of the white shark: the salmon shark, whose range extends from the glaciers of Alaska down to Baja California, where it crosses over the white sharks' territory along the continental coast, and the mako shark, which resides along the continental shelf off California. The team also has tagged thresher sharks and blue sharks.

Sharks are a vital part of oceanic ecosystems. As the top predators in the food chain, they regulate the populations of the species below them. If shark populations get in trouble, it can trigger a cascading effect all the way down the food chain. The TOPP team has used several distinct tag technologies to get a simultaneous view of how these sharks divide up the ocean turf.

Salvador Jorgensen, a postdoctoral researcher at Stanford University's Hopkins Marine Station and the Monterey Bay Aquarium, is part of the group that has been tagging and monitoring white sharks, more popularly known as great white sharks.

Jorgensen is scheduled to discuss the team's work during a symposium titled "Will Too Few Jaws Take Too Big a Bite" The Importance of Sharks to Ocean Ecosystems," beginning at 10:30 a.m. Sunday, Feb. 17, at the American Association for the Advancement of Science (AAAS) annual meeting in Boston. He also will discuss the work at a press briefing about the symposium scheduled for 3 p.m. that afternoon.

What they have found has opened up a whole new vista in the white shark's world. It turns out white sharks are quite the sightseers.

Jorgensen and his colleagues have tagged more than 100 white sharks along the central California coast. Home to numerous seal and sea lion rookeries, the area along the continental shelf is practically one long lunch counter for the white sharks. But in spite of the fine dining available there, the sharks exhibit an urge to roam.

Through tracking the tagged sharks, the TOPP team has found two distant destinations that the sharks favor, both of which they visit on a regular, annual travel timetable. Each winter the white sharks head out from the California coast, with some going to the Hawaiian Islands. Most, however, head to another hotspot, out in the middle of the Pacific Ocean. This second location is roughly 1,300 miles from the mainland-about half the distance to Hawaii-and a few hundred miles to the south of the direct route to the islands. Dubbed "the white shark caf" by the researchers, just what the attraction is out there remains something of a puzzle. But what is clear is that all the sharks that summer along the California coast show remarkable fidelity; when they return to the mainland, they head for the same local neighborhoods that they favor every summer.

"These animals appear again and again at very specific areas," Jorgensen said. Despite the sharks' ability to move through the ocean to wherever they please, they stick to consistent routes and destinations. It is a striking finding, because white sharks are found off South Africa and Australia, in addition to the West Coast of North America, but what the TOPP team and other researchers have found is that the populations do not appear to mix. New data presented by the TOPP team indicate that even between Pacific Ocean basin populations there are genetic differences. This means that white sharks, at least the females, have maintained long term isolation in the Eastern Pacific.

"This is really important in terms of management, so that management can focus on these population units," Jorgensen said. "And this really sets the stage for us to census the population, now that we know it is a confined population in the eastern Pacific."

There is another group of white sharks that tend to congregate near Guadalupe Island, offshore from Baja California, south of the California population that the TOPP team has been studying, but it is not yet clear whether they are distinct from the central California group.

Most of the tags used by the TOPP researchers have been electronic tags that are monitored by satellite. Those tags provide location data when the sharks are on the high seas. The other tags are acoustic tags; sensors installed along the California coast pick up the signal whenever one of the tagged sharks swims by.

The TOPP program maintains a live access server that gives regular updates on the locations of the sharks that have been tagged. "My favorite activity is to wake up and check where the sharks are," said Barbara Block, the Charles and Elizabeth Prothro Professor in Marine Sciences at Stanford University's Hopkins Marine Station.


'/>"/>

Contact: Louis Bergeron
louisb3@stanford.edu
650-725-1944
Stanford University
Source:Eurekalert

Related biology news :

1. Unveiling the structure of microcrystals
2. ESA honored at White House ceremony
3. Conquest of land began in shark genome
4. Photo-monitoring whale sharks
5. Human deaths from shark attacks hit 20-year low last year
6. New research reveals shark superhighways and hotspots
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:12/5/2016)... WASHINGTON , Dec. 5, 2016  The ... (NIJ), today published "Can CT Scans Enhance or ... examines the potential of supporting or replacing forensic ... a CT scan. In response to ... NIJ is exploring using CT scans as a ...
(Date:11/29/2016)... Nov. 29, 2016 BioDirection, a privately held ... for the objective detection of concussion and other traumatic ... successfully completed a meeting with the U.S. Food and ... test Pre-Submission Package. During the meeting company representatives reviewed ... a precursor to commencement of a planned pilot trial. ...
(Date:11/22/2016)... India , November 22, 2016 According to ... (Fingerprint, IRIS, Palm Print, Face, Vein, Signature, Voice), Multi-Factor), Component (Hardware and ... 2022", published by MarketsandMarkets, the market is expected to grow from USD ... a CAGR of 16.79% between 2016 and 2022. ... ...
Breaking Biology News(10 mins):
(Date:12/9/2016)... -- China Cord Blood Corporation (NYSE: CO ) ... provider of cord blood collection, laboratory testing, hematopoietic stem cell ... of its 2016 Annual General Meeting, which was held on ... . At the Annual General Meeting, ... Huazhen LLP as the independent auditors of the Company for ...
(Date:12/9/2016)... 9, 2016 According to a new market ... Custom, Predesigned, Reagent Equipment), Application (Research, PCR, Gene, DNA, NGS, Diagnostic, ... by MarketsandMarkets, the global market is expected to reach USD 2.20 ... CAGR of 10.6% during the forecast period. ... ...
(Date:12/8/2016)... This report analyzes the worldwide markets for Biostimulants in US$ ... Fulvic), Extract Based, and Others. The report also analyzes the ... Row Crops, and Others. The report provides separate comprehensive analytics ... Japan , Europe , ... Rest of World. Annual estimates and forecasts are provided for ...
(Date:12/8/2016)... SAN DIEGO, Dec. 8, 2016  OncoSec Medical ... company developing DNA-based intratumoral cancer immunotherapies, today announced ... "We are delivering on our ... melanoma with ImmunoPulse┬« IL-12. We are pleased with ... melanoma combination trial, and we are focused on ...
Breaking Biology Technology: