Nov-05-2009Researchers Study Great White Shark Migration
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CONTENTS:SOURCESFIND OUT MORE ON THIS SUBJECTGreat white sharks, known scientifically as Carcharodon carcharias, can reach lengths of 20 feet and weigh 3 tons. They live worldwide in cool, coastal waters and have a well-developed sense of smell and eyesight. They have an innate ability to sense changes in water pressure and electrical pulses, which helps them find prey. When in Northern California, they feed on seals and sea lions. The area they roam has been known for years as the red triangle, a scary-sounding name that many marine biologists shun because it seems to bolster the notion that great whites are killing machines like the beast in the movie "Jaws." The scientists hope this study will shed more light on these fierce yet sophisticated hunters and their important role in the ecosystem. The fact that they are genetically isolated from other white sharks makes them all the more vulnerable, researchers said. It can't be comforting for swimmers at Aquatic Park to know that the acoustic tags recorded five great whites inside the entrance to San Francisco Bay in 2007 and 2008. The researchers don't know what the sharks did or how long they stayed, but it does suggest to swimmers that flopping around in the water between August and December might not be a good idea. "Think about it like this: We've got this great big ocean and these are some of our best-known predators and yet we hardly knew anything about where they went or their movements until now," Block said. "This research can lead to decreased interactions with sharks and help us ensure their protection for future generations."
[1] The researchers used a combination of satellite and acoustic tags to follow the migrations of 179 individual white sharks between 2000 and 2008. These sharks were adults or sub-adults that ranged in size up to 4,000 pounds, and were individually tagged at sites along the central California coast, including the Gulf of the Farallones, Tomales Bay and Año Nuevo. The electronic tags reveal that the sharks spend the majority of their time in three areas of the Pacific: the North American shelf waters of California; the slope and offshore waters around Hawaii; and an area called the "White Shark Café," located in the open ocean approximately halfway between the Baja Peninsula and the Hawaiian Islands. "The thing we've learned about white sharks," said Scot Anderson, a marine biologist with the National Park Service, who has been involved in white shark research in Northern California for more than two decades, "is that they're not swimming around aimlessly -- they are very selective predators."
[2] Acoustic receivers detected five white sharks beneath the Golden Gate Bridge. There are no data to indicate how far the sharks crossed into the bay or why, but the researchers say it's likely they were
hunting seals and sea lions in the region. More broadly, the study revealed great whites spend the majority of their time in three areas of the Pacific: the North American shelf waters of California; the slope and offshore waters around Hawaii; and an area called the White Shark Caf'," in the open ocean about halfway between the Baja Peninsula and the Hawaiian Islands. "The thing we've learned about
white sharks," said study co-author Scot Anderson, a marine biologist with the National Park Service, "is that they're not swimming around aimlessly -- they are very selective predators."
[3] Surfers in northern California were donning their wetsuits a little more gingerly yesterday after a study of the Pacific's great white sharks showed just how close to the shore the fearsome predators are lurking. The sharks cruise the beaches and rocky points to keep close to the colonies of seals and sea lions that make up their main diet. They occasionally even head under the Golden Gate Bridge into San Francisco Bay, according to
a ten-year study published in the scientific journal, Proceedings of the Royal Society B.
[4] The predators can be found near
California '''s northern and central coast between August and February, according to a study published Tuesday in the Proceedings of the Royal Society. The Washington Post reports that California-based scientists discovered Pacific white sharks in San Francisco Bay, near the Golden Gate Bridge, and say that means they'''re also likely to be near populated beaches.
[5] The ferocious great white sharks of Northern California spend their time devouring sea lions, traveling, mating and, occasionally, touring San Francisco Bay, but they never socialize with sharks from other regions, according to a Stanford University-led study released Tuesday.
[1] Oh, and by the way, researchers also tracked five great whites entering San Francisco Bay, presumably seeking out seals and sea lions. The sharks were detected frequently at their chosen site, which means that they are patrolling around there nearly constantly, for long periods of time. They will occasionally visit one of the adjacent sites, but they always come back. As for how far back this population became isolated, the paper says genetic studies indicate that northeastern Pacific white sharks likely originated from a small population which arrived sometime in the last 200,000 years -- and hasn't intermixed with populations from outside the region since.
[6] Researchers have long thought that white sharks migrated across oceans, but a new study in the Proceedings of the Royal Society B shows that the population in the northeastern Pacific Ocean, along California, hasn't mixed with other white sharks for tens of thousands of years.
[7] Scientists with the Tagging of Pacific Predators (TOPP) program combined satellite tagging, passive acoustic monitoring and genetic tags to study white sharks (Carcharodon carcharias) -- popularly known as great white sharks -- in the North Pacific. The team consisted of researchers from Stanford University, University of California-Davis, Point Reyes Bird Observatory and the Pelagic Shark Research Foundation, and the details of their study are to be published online Nov. 3 by the Proceedings of the Royal Society B. The fact that the northeastern Pacific white sharks undergo such a consistent, large-scale migration, and that they are all closely related and distinct from other known white shark populations, suggests that it is possible to conduct long-term population assessment and monitoring of these animals.
[2] The study was conducted by scientists from Stanford, UC Davis, the Point Reyes Bird Observatory and the Pelagic Shark Research Foundation. The researchers used a decoy to lure the sharks to their boat, where they took tissue samples and used a dart attached to a pole to affix satellite and acoustic monitoring devices to 179 great whites along the coast.
[1] The other two concentrations of Carcharodon carcharias are off the coast of South Africa, and in the waters between Australia and New Zealand. It had long been assumed shark species at the top of the ocean food chain that roam the high seas looking for food and mates did so almost randomly. Using satellite tagging, acoustic monitoring of shark "hot spots" and genetic samples, a research team led by Barbara Block of Stanford University found -- to their surprise -- that the eastern Pacific's Great Whites are real homebodies.
[8] One "hotspot", between Hawaii and Mexico, is so popular that the scientists have named it the "white shark cafe". Dr Salvador Jorgensen, of Stanford University's Hopkins marine station, found that in winter, sharks leave seal colonies, where they feed all summer, and set off for warmer waters. The sharks tend to split their time between the coast and the ocean, said the researchers who published their findings in the journal Proceedings of the Royal Society B. However it is not known why they meet as the "white shark cafe" area is not thought to be especially rich in food.
[9] Whenever a tagged shark came within 850 feet of a receiver, a code for that particular shark would be transmitted. The tags revealed that although they are loners, the sharks all follow pretty much the same route and hang out in the same places. After feasting in Northern California, they hit the waters around Hawaii and take a yearly respite in a mysteriously alluring mid-ocean spot that researchers are calling the "white shark cafe." What they do in the shark cafe, which is halfway between the Baja Peninsula and the Hawaiian Islands, is a mystery, but sex is believed to play a part. "What we know," said Salvador Jorgensen, a postdoctoral fellow at the Hopkins Marine Station who co-authored the study, "is that all of them leave the coast in the winter and all of them end up either in the cafe or offshore in Hawaii."
[1] Sharks tagged with acoustic devices often spent up to 107 days at four key sites along the central and northern California coast where seals and sea lions are abundant: Southeast Farallon Island, Tomales Point, A'o Nuevo Island and Point Reyes. "The
sharks were detected frequently at their chosen site," said Salvador Jorgensen, a postdoctoral researcher at Stanford University. This means "they are patrolling around there nearly constantly, for long periods of time. They will occasionally visit one of the adjacent sites, but they always come back."
[3] The acoustic-tagged sharks spent time at four key sites along the central and northern California coast, each of which supports large colonies of seals and sea lions: Southeast Farallon Island, Tomales Point, Año Nuevo Island and Point Reyes. The tags revealed that often sharks had favorite sites where they would remain resident for up to 107 days, although they occasionally would make brief visits to the other nearshore hot spots. "The sharks were detected frequently at their chosen site," Jorgensen said, "which means that they are patrolling around there nearly constantly, for long periods of time. They will occasionally visit one of the adjacent sites, but they always come back."
[2] 
The study, the largest and most detailed study of North American great white sharks, provides evidence contrary to the popular notion of great white sharks swimming aimlessly in the ocean. The sharks under study divided most of their time between three locations: Northern California, Hawaii, and an area that the researchers called the white shark caf'', a spot in the open ocean about halfway between the Baja Peninsula and the Hawaiian Islands.
[10] Researchers also discovered that the sharks seem to congregate in an area dubbed the "White Shark Café", located in the ocean approximately halfway between the Baja Peninsula of California and the Hawaiian Islands.
[4] HONOLULU -- Ten California-based researchers said they now know great white sharks migrate from California to the Hawaiian Islands regularly.
[11] Molecular geneticist Carol Reeb, a research associate at Stanford, said, "If you had asked us a few years ago, we would have said white sharks found in California probably migrated throughout the Pacific. Now, even though we know they travel great distances, their paths are surprisingly constrained to specific routes. This explains how a highly migratory marine species becomes a genetically isolated population. This also makes it much easier to appreciate how vulnerable the northeastern Pacific white shark population could become if too many individuals were taken as either catch or bycatch, since these sharks do not appear to interbreed with other shark populations."
[2] Washington, November 4 - ANI: In a new research, scientists have found that the migratory behaviors of the white shark has lead to the formation of isolated populations in the northeastern Pacific Ocean that are genetically distinct from sharks elsewhere in the world.
[12] PARIS — Great Whites may be loners, but the ocean's most feared predators also hang out together between Mexico and Hawaii at a deep sea watering hole known as the "White Shark Cafe," a study released Wednesday reveals. No animals inspire more fascination and frissons, but scientists admit to knowing precious little about how the endangered Great Whites get around and get it on as they navigate the globe's oceans. Like other open water sharks prized for their meat -- and, in Asia, especially for their fins -- the magnificent hunting machines are threatened with extinction, according to experts. The new study identifies a distinct population and a major new genetic grouping of the Great White in the eastern Pacific, only the third such "clade" ever found.
[8] The scientists tracked the snaggly toothed predators between 2000 and 2008 from the Bay Area to San Diego, Hawaii and back as the sharks followed a route that was carried out with surprising precision and under a strict time frame. These great whites have been isolated from other great white sharks near Australia and South Africa for so long that they are now genetically distinct.
[10] The magnificent predators, which have for years struck fear in Bay Area surfers, abalone divers and swimmers, have been isolated from other white shark populations for so long that they are genetically unique to the world, the researchers concluded.
[1] Scientists said they probably meet there to mate but also just to forage and "hang out" together. "The thing we've learnt about white sharks is that they're not swimming around aimlessly -- they are very selective predators," Scot Anderson, a marine biologist with the National Park Service, said. Surfers and swimmers in the waters of northern California have known for years that great whites are in the water -- warnings are posted at many beaches -- but this is the first scientific proof of how often humans will be sharing the surf with 4,000-pound predators up to 15 feet long.
[4] Between August and December, the Great Whites -- which can grow up to six metres (20 feet) and three tonnes -- stalk waters off the coast of central and northern California, feasting on seals and sea lions. Their preferred hunting grounds in this area are known as the "red triangle", notes the study, published in the British journal Proceedings of the Royal Society B. Starting in January, they head for the deep blue around Hawaii some 4,000 kilometers (2,500 miles) to the west, where they are found in largest numbers between April and July.
[8] The sharks lived in the deep ocean near Hawaii between January and July and in Northern California between August and December. Surprisingly, the researchers found, the great beasts occasionally strayed from their Northern California feeding grounds for jaunts under the Golden Gate Bridge into San Francisco Bay, apparently in search of snacks.
[1] The researchers were also surprised to find five white sharks in San Francisco bay. The massive sharks swam directly beneath the Golden Gate Bridge where distinct sounds from their acoustic tags were picked up by an acoustic receiver meant to track salmon.
[7] Researchers in California tracked 179 great whites over 10 years, using acoustic tags and satellite info. Rather than wandering the sea at random, they spend winter months just off the California coast--and even venture into San Francisco Bay. "It shows you how wild it is off our West Coast of North America," one researcher tells the Washington Post. "This is Yellowstone."
[13] The team also was surprised to learn about new movements that the acoustic tags revealed in some nearshore locations. They found five white sharks were detected on acoustic receivers beneath the Golden Gate Bridge that originally were installed to listen for salmon, which migrate from the bay to the sea and back again.
[2] Employing satellite tapping, passive acoustic monitoring, and genetic tags, researchers with the Tagging of Pacific Predators (TOPP) found that the white shark ( Carcharodon carcharias ) in northeastern Pacific frequently return to the same spot over and over, and sometimes remain in one hunting ground for over a hundred days.
[7] Scientists with the Tagging of Pacific Predators (TOPP) program combined satellite tagging, passive acoustic monitoring and genetic tags to study white sharks popularly known as great white sharks in the North Pacific.
[12] Barbara Block, professor of marine sciences at Stanford and a coauthor of the paper, said, "Catastrophic loss of large oceanic predators is occurring across many ecosystems. The white sharks' predictable movement patterns in the northeastern Pacific provide us with a super opportunity to establish the census numbers and monitor these unique populations. This can help us ensure their protection for future generations."
[2] The northeastern Pacific population may have been founded by a relatively small number of sharks in the late Pleistocene -- within the last 200,000 years or so, genetic research shows. Other distinct other populations of white sharks are concentrated near Australia and South Africa.
[3] ScienceDaily (Nov. 4, 2009) - The white shark may be the ultimate loner of the ocean, cruising thousands of miles in a solitary trek, but a team of researchers has discovered that the sharks have maintained such a consistent pattern of migration that over tens of thousands of years the white sharks in the northeastern Pacific Ocean have separated themselves into a population genetically distinct from sharks elsewhere in the world.
[2] Jorgensen believes the pattern of migration has been so consistent over thousands of years that white sharks in the northeastern Pacific Ocean have become a genetically distinct species.
[1] Studies of maternally inherited mitochondrial DNA sequences show that the populations are distinct, and suggest that the northeastern Pacific population may have been founded by a relatively small number of sharks in the late Pleistocene within the last 200,000 years or so. According to Molecular geneticist Carol Reeb, a research associate at Stanford, Even though we know they travel great distances, their paths are surprisingly constrained to specific routes.
[12] The DNA samples showed that local white sharks descended from a relatively small number of sharks in the South Pacific between Australia and New Zealand in the late Pleistocene era, some 200,000 years ago, but have not mixed with other populations since then.
[1] Great white sharks tend to patrol specific neighborhoods for weeks on end, a new study finds. Despite their ability to migrate thousands of miles, great whites in the Pacific were found to be a distinct genetic group compared with great whites elsewhere.
[3] If you asked use a few years ago we would have said white sharks found in California probably migrated throughout the Pacific. Now, even though we know they travel great distances, their paths are surprisingly constrained to specific routes.
[6] Great white sharks, much like humans, tend to stick to familiar turf, according to new research. Like a lot of people, they like to hang out along the coastal waters of California.
[10] Shark researchers say great white sharks are more curious than anything when it comes to people in the water. It is believed, however, that they will mistake a surfer sitting on a surfboard for a sea lion and that's when the Great Whites will sometimes go in for a bite.
[14] NEWPORT, Ore.--'' The recent string of shark sightings near towns along the central coast of Oregon, has sparked some worry in people about the increase of Great White Sharks. Earlier in the year, a man pulled up a Great White Shark that was snagged in his crabbing gear.'' Then a few more sightings were reported by surfers in the area, some said there was even a person bumped off their board by a shark.
[15] Lead researcher Salvador Jorgensen explains that male white sharks "converge in a very specific area of the cafe," Jorgensen said, while female sharks move in and out of the area. "It adds a little more evidence to the argument that this could be an important reproductive area".
[10] White sharks are a large, highly mobile species, said Salvador Jorgensen, a postdoctoral scholar at Stanfords Hopkins Marine Station. They can go just about anywhere they want in the ocean, so its really surprising that their migratory behaviors lead to the formation of isolated populations, he added.
[12] "What we see on our acoustic monitoring devices is that the sharks stay pretty close to pinnipeds," said Barbara Block, a professor of Marine Sciences at Stanford's Hopkins Marine Station and a co-author of the paper. "It gives me more confidence knowing where the white sharks are going to be."
[1] By attaching 78 acoustic tags that create a unique ping or acoustic code for each tagged shark, the researchers were able to detect when the white sharks came within 250 meters (820 feet) of a receiver. This allowed the researchers to discern their pattern of coastal movements in high detail. The tags revealed that often sharks had favorite sites where they would remain resident for up to 107 days, although they occasionally would make brief visits to the other nearshore hot spots.
[12] A white shark tagged with both acoustic (front) and pop-up satellite (rear) tags.
[2] Using satellite tags and acoustic tracking systems, The Royal Society said Great Whites come into Hawaiian waters at least once a year and may stay as long as two months.
[11] The new findings will help conservation efforts, the study concludes: "The population's fidelity to predictable locations offer clear population assessment, monitoring and management options." A third of the world's open water sharks -- including the Great White and hammerhead -- face extinction, according to the largest ever shark survey, completed earlier this year by the International Union for the Conservation of Nature (IUCN).
[8] It looks like "Jaws" may not be so far-fetched after all. While humans have commonly thought that great white sharks rarely swim close to shore, a new study has discovered they do during several months of the year.
[5] The study, the largest and most detailed analysis of the great white sharks of North America, was published today in the scientific journal Proceedings of the Royal Society B.
[1] Credit: Neil Hammerschlag / www.neil4sharks.org A great white shark successfully lunges for and captures a juvenile fur seal in False Bay, South Africa.
[3] The other populations of white sharks are concentrated near Australia and South Africa.
[2] The sharks' movements between California and Hawaii are so standardized the population has become genetically distinct from other groups of great whites. Their proximity to humans "shows us the sharks are really minding their own business.
[13] Researchers said the great whites that visit Hawaii normally stay several miles offshore in deeper water. They said they don't know why, but theorize they could be feeding on something, perhaps squid, or some other food source. In California, the whites get closer to shore where they feed on seal populations. When the great whites are in Hawaii, they move around a lot, but for the most part, they stay in about 300 feet of water, which may be they are rarely seen. This material may not be published, broadcast, rewritten or redistributed.
[11] The researchers speculate that the sharks were hunting seals and sea lions in the area. The situation worsens when only sharks taken in high-seas fisheries are considered: 52 percent of these species are threatened. According to a report from the Australian Government and TRAFFIC--an organization that monitors wildlife trade both legal and illegal--the collapse of shark populations is being caused largely by rising demand for shark fin in Asia.
[7] There are currently no detectors in San Francisco Bay, so there are no data to indicate how far or why the sharks crossed into the bay; however, seals and sea lions are in the region and could be potential prey for the large sharks.
[2] Popular Stinson Beach, north of San Francisco, was closed for five days in August after a surfer spotted a shark, 8 to 10 feet long, about 125 yards offshore.
[4] Veteran Surfers at Agate Beach say there has always been a good amount of sharks along the Oregon Coast.'' They say there is no reason to be alarmed about the increase in shark reports because the ocean is where sharks live and people are bound to see a fin of the fierce predator eventually. They say when they see a shark in the water, they get out and return at another time.
[15] The scientists tracked the snaggly toothed predators between 2000 and 2008 from the Bay Area to San Diego, Hawaii and back as the sharks followed a route that was carried out with surprising precision and under a strict time frame.
[1] Five sharks also were acoustically detected close to shore in Hawaii off Waialua Bay and Kualoa Point on Oahu, and off the coast of Kona.
[2] Some -- especially males -- loiter at a halfway point known as the "White Shark Cafe", with females coming and going for what scientists presume is a bit of shark intimacy.
[8] "When I go to the beach, I look at it differently," says Stanford University marine sciences Prof. Barbara Block, who co-wrote the paper. "These animals are coming in so close to shore because that's where the pinnipeds are." The scientists, who tagged 179 Pacific great whites to track their migrations, also discovered the beasts then left the California coastline and traveled 1,240 to 3,100 miles to the Hawaiian islands.
[5] Various monitoring methods show that white sharks in the northeast Pacific return to the same spots over and over again, sometimes remaining in one hunting area for over one hundred days.
[6] Genetics techniques were used to examine the relationships of the California sharks to all other white sharks examined globally.
[12] Great white sharks, previously thought to be solitary hunters scouring the seas for prey, may also have a sociable side.
[9] The elevated. The pup is just 23.5 centimeters in length and weighs 125 grams.Named for their large wing-shaped. Earlier this summer he traveled to Australia to dissect a rare 8-foot great white shark, and help create the. These fearsome yet charismatic fish continue to fall victim to overfishing and many are now at risk of extinction as a result.
[2] Don't start packing up your beach gear too soon. Stanford University post-doctoral scholar Salvador Jorgensen, the paper's lead writer, says the sharks often ignore the humans crossing their path. "The number of interactions with people is very small," he says
[5] Photo courtesy of NOAA. "The sharks were detected frequently at their chosen site," Jorgensen said, "which means that they are patrolling around there nearly constantly, for long periods of time. They will occasionally visit one of the adjacent sites, but they always come back." They also never stray far.
[7] The world's largest shark has long fascinated humanity from the novel and film Jaws to recent sumptuous footage of the sharks catching sea lions in Planet Earth.
[7] There have only been ten documented deaths in 99 attacks in more than 50 years in California -- most were surfers or divers in places where elephant seals and sea lions abounded.
[4] All of us who live near San Francisco have heard this for years. They sit off the Farallon Islands and eat seals all winter.
[13] The sharks, tagged around the Farallon Islands, A'o Nuevo Island, Point Reyes and Tomales Point, ranged from adolescent to fully grown sharks weighing 4,000 pounds.
[1] Christopher Perle, a Stanford graduate student in biology, is also a coauthor of the paper. Other coauthors are A. Peter Klimley, an adjunct associate professor at UC-Davis; Taylor Chapple, a graduate student at UC-Davis; Sean Van Sommeran, executive director of the Pelagic Shark Research Foundation; Callaghan Fritz-Cope, operations director of the Pelagic Shark Research Foundation; and Adam C. Brown, of the Point Reyes Bird Observatory.
[2] The tags revealed that the sharks travel a regular route, spending the months between August and December off the beaches of California before swimming to the waters around Hawaii for the spring and summer. [4] The behemoth, who at times can reach seven meters in length, has also become famous for occasionally attacking swimmers and surfers, though scientists believe the sharks do not intentionally hunt humans.
[7] Over an eight year period, nearly 100 sharks were electronically tagged, and even more had tissue samples taken by scientists working from a ship. Not only do the sharks consistently migrate along the same paths, they stick to a schedule too.
[8] Acoustic listening receivers were placed at dozens of locations across the ocean floor at known shark hot spots.
[1] The string of shark sightings has lead some people to worry about the possibility of an increase of the ocean predators.''
[15] The research team placed acoustic listening receivers on the ocean floor at sites thought to be high residency areas, or hot spots.
[12] The scientists hope to use the new information that the Pacific population is distinct from other to help save the species, which is classified as Vulnerable to extinction by the IUCN Red List. [7] SOURCES1.
Great white shark study2.
Tags Reveal White Sharks Have Neighborhoods In The North Pacific3.
Where Great White Sharks Lurk: Close to Home | LiveScience4.
Great white sharks lurk close to the shore in northern California - Times Online5.
Scientists: Pacific great white sharks often swim close to shore, beaches6.
Great White Sharks Along California Coast Are Unique Population - Haven't Met Outsiders in 10,000+ Years : TreeHugger7.
California's great white sharks are a distinct population8.
AFP: Great Whites hang out in Pacific's'shark cafe'9.
Great white sharks 'hang out' together - Telegraph10.
The Secret Lives and Loves of Great White Sharks | 80beats | Discover Magazine11.
Researchers Study Great White Shark Migration - Honolulu News Story - KITV Honolulu12.
Migrating white sharks form isolated populations in northeastern Pacific Ocean13.
On Calif. Coast, Great Whites Lurk Closer Than You Think - Science & Health News Summaries | Newser14.
What are great whites doing at the Oregon coast? | KATU.com - News, Weather and Sports - Portland, Oregon | Outdoors Featured15.
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