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Creature Feature: Great White Shark

Posted Tue, Aug 14, 2012 by Michelle Cassidy to atlantic, california, creature feature, discovery channel, endangered species act, great white sharks, jaws, mexico, pacific, shark week

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Great whites have earned a bad reputation, but they don't deserve it ©Discovery Channel

They’re the stars of Shark Week, one of the most iconic creatures in the ocean. But how well do you really know the great white shark?

White sharks are known by many names—great white, white pointer, Carcharodon carcharias, even white death. They’re the largest existing predatory fish in the ocean, and they’ve been around for about 16 million years. They’re found in coastal waters in all of the world’s major oceans.

The average great white measures in around 14 feet long (the females are generally a few feet longer than the males). An average individual weighs between 1,500 and 2,400 pounds. The largest white sharks ever measured came in around 20 feet long and weighed nearly 5,000 pounds.

All that size makes these sharks powerful predators. Their bite force is an estimated 1.8 tons—that’s 20 times the bite force of the average human! This powerful bite is coupled with multiple rows of sharp, serrated teeth that help the shark saw off pieces of fish.

Great whites also have an additional sense that allows them to detect the electromagnetic field emitted by the movement of living animals. By searching for these tiny electromagnetic pulses and using their excellent sense of smell, sharks can seek out prey from miles away.

In the social structure of white sharks, females dominate males, and size matters. They resolve conflict through rituals and displays of power, and rarely attack one another. Some sharks have even shown behavior that appears playful!

Great whites have earned a bad reputation as ferocious man-eaters due to movies like Jaws and stories about rogue sharks attacking humans. Truth is, great whites aren’t all that interested in humans. They would rather eat a fish or a seal than a human. While a significant proportion of shark accidents around the world involve white sharks, most are not fatal. Great whites are curious sharks, and will give an unknown object a sample bite, then release it.

These powerful creatures may be at the top of the food chain, but their biggest predator is humans. Only a few hundred great whites are left in the population off the coasts of California and Mexico, and they’re not getting the protection they need. Sign today to help get great whites covered by the Endangered Species Act.


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Save Shark Week’s Stars

Posted Mon, Aug 13, 2012 by Ashley Blacow to bycatch, california, discovery channel, endangered species act, federal government, great white sharks, jaws, juvenile sharks, mercury, mexico, petition, shark week

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Great white sharks keep the oceans healthy and balanced ©NOAA

Whether you fear them or admire them, most people have an instant reaction when they hear great white shark.  

Intrigue, mystery, and terror have guided attention on great white sharks since they lit up the screens in the 1975 thriller “Jaws.” The film made history 37 years ago for its chilling characterization of these powerful sharks, and swimming in the open ocean has never been the same since.

Great whites are making history once again, this time for their globally declining populations from bycatch in commercial fisheries, capture in beach protective nets, and slaughter for their fins, teeth, and jaws in the shark fin and curio trade.

Here on the US West Coast, new scientific studies have shed light on the status of great white sharks off California and Baja California, Mexico. Our great white sharks are even more unique than we thought; in fact they are genetically distinct and isolated from all other great white sharks around the world. They congregate off Mexican Islands and the “red triangle” off Central California (including the Farallon Islands, Point Reyes, and Point Sur), and make extensive offshore migrations to the distant “white shark Café” and even to the Hawaiian Islands.

But, sadly there may be as little as a few hundred adult great white sharks remaining in this population, far less than anyone expected. This low population alone puts these great whites at great risk of extinction from natural and human-caused impacts. Continued existence of these West Coast great white sharks is threatened by their low population size, inherent vulnerability to capture, slow growth rate, low reproductive output, and the ongoing threats they face from human activities. This is why Oceana is petitioning the federal government and the state of California to list this population of iconic sharks on the Endangered Species List.

What is threatening great white sharks off California and Mexico?

Young great white sharks are un-intentionally caught as bycatch in commercial fishing entangling nets. Set and drift gillnets--which together target California halibut, yellowtail, white seabass, thresher sharks and swordfish--catch great white shark pups in their nursery grounds.

Since 1980, over 10 great white shark pups have been reported being caught in these nets every year. The scary part is that monitoring of bycatch on these fishing vessels is very low so take of these pups remains underreported. In other words, more great white sharks are caught than we are aware.

Additionally, young great white shark “pups” caught in their nursery grounds off the Southern California coast have the second highest mercury level tested on record for any sharks worldwide. These mercury levels exceed six-fold the established thresholds where harmful physiological effects have been documented in other marine fish. Levels of harmful contaminants of PCBs and DDTs in their liver tissue are the highest observed in any shark species reported to date globally.

Endangered species status will bestow additional protections to white sharks, including better monitoring and management to reduce fishery bycatch and additional research to further understand these fascinating top predators of the sea.

As much as we may fear them for their bad rap, we need great white sharks to keep our oceans healthy. Just as wolves keep deer populations under control, great white sharks play a critical top-down role in structuring the marine ecosystem by keeping prey populations in check, such as sea lions and elephant seals, benefiting our fisheries and abundant wildlife.

Listing the West Coast population of great white sharks on the Endangered Species List will help us learn more about the lives and threats of these amazing animals through additional research funding and protection measures.

Please help us in our efforts to protect US West Coast great white sharks from extinction by signing a letter of support for their listing on the Endangered Species Act.


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This Shark Week, Save Great Whites

Posted Thu, Aug 9, 2012 by Michelle Cassidy to baja california, california, commercial fishing, discovery channel, endangered species, endangered species act, great white sharks, mexico, oregon, pacific ocean, shark week, sharks, Washington

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Great whites play an important role in the ocean ecosystem ©Terry Goss

During Shark Week we love watching majestic great whites on TV, but if we don’t act soon to protect them, recordings will be the only place they exist.

In the Pacific, great whites are important predators. As the largest predatory fish on the planet, they can reach lengths over 20 feet and weigh more than 5,000 pounds. They’re shaped like torpedoes and can swim through the water at speeds of up to 15 miles per hour. Great whites can detect electromagnetic currents in the ocean and have such a sharp sense of smell that they can identify blood in the water from up to 3 miles away.  You can’t deny that these are impressive animals.

As fearsome as they might be as predators, they’re not the killing machines that they’re often identified as. They use all those prey-detecting skills to help keep the marine food web intact — without great whites, the ocean’s balance would be thrown off.

But that might be what the future holds, if nothing is done. A recent study found that there may only be a few hundred adults left swimming off the coast of California and Mexico, far fewer than anyone expected. And those that are left face deadly dangers from fishing nets.

Newborn great whites are often killed by commercial fishing gear off of Southern California and Baja California, making it hard for the populations to stabilize.

Sharks have inhabited the oceans for more than 400 million years and now they’re disappearing because of human actions. We’re working to get US great whites the protection they need — sign today to help get great white sharks on the Endangered Species Act.

Shark Week starts on Sunday – stay tuned for lots more sharky updates!


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Oceans in the Spotlight at COP16

Posted Tue, Dec 7, 2010 by elly to cancun climate negotiations, climate change, cop16, mexico, ocean acidification, UN climate conference

Oceana marine scientist Ellycia Harrould-Kolieb is at the UN climate negotiations in Cancun this week.

This weekend at COP16 started off with style (or perhaps lack thereof) at the NGO party at Señor Frog’s – an infamous nightclub catering to 20-something American spring-breakers in Cancun. The NGO party is a great event that lets the climate community put on their party clothes and let off a little steam - before heading into the second very grueling week of negotiations.

Saturday was Oceans Day, an all-day event that focused on the issues facing the oceans due to increasing carbon dioxide levels. On the agenda this year were ocean acidification (a panel including myself, Carol Turley and Tony Haymet), blue carbon and coastal adaptation.


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