In the early dawn of March 31, 2005, researchers from the Monterey Bay Aquarium made history. Standing on a small boat far off the coast of California, they carefully lifted a sling carrying a six-foot-long great white shark over the side and — splash! — the powerful fish was back in the wild, after spending a record 198 days at the aquarium.

As NATURE’s Oceans in Glass shows, displaying a great white — one of the sea’s most impressive predators — has long been a dream of aquariums around the world. But previous efforts to care for the sharks — which can grow to weigh two tons and measure 21 feet long — have largely ended in failure. The great whites proved too big, too aggressive, or too sensitive to live penned up. Some wouldn’t eat, says biologist Dr. Randy Kochevar of the aquarium, “and sharks can’t survive long if they aren’t feeding.”

In Monterey, however, biologists working on the aquarium’s shark conservation and ecology project believed it was possible for a great white to survive — and thrive — in one of the facility’s giant display tanks. They also believed that letting the public see these magnificent hunters up close could pay big dividends for their efforts to protect sharks, which are under increasing threat.

With this goal in mind, several years ago the aquarium’s researchers began experimenting with ways to keep a captive shark happy. First, they built an enormous 4-million-gallon pen in the ocean off Malibu, California. When commercial fishing boats accidentally caught a great white, the aquarium arranged for it and several others to be moved to the pen. There, researchers learned to feed the sharks and understand how they behaved in captivity.

Those lessons bore fruit in August 2004, when a commercial halibut fisherman caught a young, five-foot long female great white in the waters off Huntington Beach. After being held in the Malibu pen for three weeks, she was moved to the aquarium for display. Over the next six months, nearly one million people came to see her. “She was an incredible ambassador for white sharks and shark conservation,” says Kochevar.

But the young shark was also growing bigger and more restless. “She basically grew more than a foot and gained 100 pounds,” according to Kochevar. “And one day she apparently decided she needed to increase the breadth of her diet,” which consisted mostly of salmon and other fish fed to her by aquarium staff. The great white began stalking other animals in the tank, eventually attacking two smaller soupfin sharks. The staff decided it was time to release the growing animal back into the wild, but not before she provided one last service to science.

This great white shark was at the Monterey Bay Aquarium for about six months.

On their way to the release site, researchers attached a sophisticated electronic tag to the shark that would record her movements for 30 days and then pop off, transmitting its location to a satellite for retrieval. Similar tags have helped revolutionize our understanding of the habits of a myriad of animals, from sharks and sea turtles to seals and bluefin tuna. Indeed, the aquarium is part of an innovative effort — called the Tagging of Pacific Pelagics (TOPP) project — that is harnessing all kinds of marine animals to carry sensors into the ocean.

In the great white’s case, the tag worked perfectly. After popping off the shark on schedule, the tag was retrieved from surly seas off the coast of Santa Barbara by Stanford University doctoral student Kevin Weng. “They lose container ships out there!” he exclaimed after using a long-handled net to scoop the tag out of the whitecaps.

The researchers say the tag showed that after being released, the shark swam more than 100 miles offshore and to depths of greater than 800 feet. “It’s clear she survived and thrived,” says Kochevar, adding that the shark first swam several hundred miles south along the California coast, “then took a hard right and headed offshore for a while, then returned to the coast. … There’s no question that she was hunting and feeding on her own.”

Similar data from other young sharks is beginning to give scientists a picture of how these animals use the ocean and how people could improve conservation efforts, according to Kochevar. There is little question that the great white’s brief stay at the Monterey Bay Aquarium has helped stoke public support for shark research and conservation, he adds. Not long ago, the aquarium’s trustees decided to increase their shark research budget by half a million dollars.

To learn more about the TOPP project, visit http://topp.org/.

Researchers have learned a great deal about how this curious creature could make such a phenomenal voyage. Some of the most valuable information was gained from a single voyage. Scientist Wallace J. Nichols released the captive loggerhead turtle, Adelita, into the Pacific a decade ago. Over the course of a year, Adelita did what no sea turtle had ever done before, she took researchers and turtle enthusiasts along on her journey, to her beach, to nest. Since then, researchers have shed much light on how sea turtles like loggerheads navigate the astounding trip. One of the more fascinating aspects of this navigation is the turtle’s use of magnetic mapping to chart its course.

To order a copy of Voyage of the Lonely Turtle, please visit the NATURE Shop.

Online content for Voyage of the Lonely Turtle was originally posted April 2007.

Some 300 miles off Costa Rica is Cocos Island, a tiny Pacific outpost that was once a favorite haunt of pirates. Cocos, a designated World Heritage Site, lies directly in the path of powerful ocean currents that often collide with the island, churning the waters into an undersea storm. Welcome to Shark Mountain. Buy the DVD. This film premiered on November 14, 2004.

Sharks have long served as the nefarious subject of stories told by everyone from seafaring captains to Hollywood screenwriters. But researchers say sharks don’t deserve their nasty reputation. To separate shark fact from shark fiction, read on.

Myth: All sharks are large and appear menacing.

Fact: The 400 plus kinds of sharks known to exist range in size from the tiny, 6-inch long cigar shark to the 45-foot long, gentle whale shark. While some come in a menacing gray color, others are brightly colored in beautiful patterns. Not all sharks have rows of razor-sharp teeth. In fact, some grind their food with flat teeth, and others don’t even need their teeth to eat, like the gigantic whale shark, which sifts food out of the water using rake-like gills.

Myth: Sharks eat humans.

Fact: Most sharks do like meat but fish, squid, seal, porpoise, or whale make a shark’s perfect meal. Some sharks, like the giant whale and basking sharks, only eat tiny plankton. Some sharks can go days or weeks without eating at all. Contrary to public perception, sharks attack less than a hundred people a year on average. Often the attacks are accidental and are rarely fatal. In fact, more people are killed each year by dogs, lightning, and even falling soda machines than by shark attacks!

Myth: There are too many sharks in the sea.

Fact: Many shark species are endangered because of pollution, loss of habitat, and excessive fishing in their environments. Furthermore, the loss of sharks imperils many ocean ecosystems since sharks play a key role in culling sick animals and keeping other populations in check.

Myth: To survive, sharks must keep moving.

Fact: All sharks do need water moving over their gills to breathe, but some species can pump water over their gills by opening and closing their mouths while resting.

Myth: All sharks can smell blood in the water from miles away.

Fact: Some sharks do have a highly developed sense of smell, which helps them hunt in the dark and detect their prey. Other sharks don’t depend on their sense of smell for foraging.

Some 300 miles off Costa Rica is Cocos Island, a tiny Pacific outpost that was once a favorite haunt of pirates. Cocos, a designated World Heritage Site, lies directly in the path of powerful ocean currents that often collide with the island, churning the waters into an undersea storm.

These swirling currents carry rich nutrients to a reef teeming with brilliantly colored marine life. Residents include moray eels, hawksbill turtles, leatherbass, bigeye jacks, red-lipped batfish, yellow barberfish, hogfish, and sea urchins, to name only a few.

The currents bring more than algae to this island paradise. They also summon an extraordinary abundance of sharks, providing a golden opportunity to observe some of the most surprising and baffling shark behavior ever captured on film. The volume and variety of sharks that visit Cocos on a regular basis is staggering, and includes huge numbers of silkies, hammerheads, black-tip reef sharks, white-tip reef sharks, silver-tip reef sharks, whale sharks, and their distant cousins, the marbled rays.

A team of expert and intrepid divers, led by renowned underwater film specialists Howard and Michele Hall, leads viewers into this ultimate domain of sharks.

To order a copy of Shark Mountain, please visit the NATURE Shop.

Online content for Shark Mountain was originally posted November 2004.

In Sharkland, you’ll learn why species that are normally found oceans apart converge in this one relatively small stretch of coastline, and you’ll be introduced to many of these unique animals, including the catsharks of the Agulhas Bank a 155-mile-wide stretch of shallow warm seas off the southeastern tip of the continent, Southern Africa’s richest fishing grounds. You’ll also explore nature’s most extreme sharks – the fastest, fiercest, smallest, and strongest – and discover the innovative adaptations that have made the Great White such an efficient killing machine.

To order a copy of Sharkland, please visit the Nature Shop.

Online content for Sharkland was originally posted May 2007.

Seafood lovers take note: there’s good news and bad news.

First, there’s the bad news for those who enjoy tuna on rye.

High concentrations of mercury, a neurotoxin that can damage developing brains in fetuses, are found in some kinds of popular fish such as albacore tuna. Swordfish and shark, king mackerel, marlin, orange roughy and tilefish also contain dangerous levels of mercury.

Women of reproductive age and young children are advised to avoid these types of fish and limit overall consumption of all fish to no more than 12 ounces per week, according to the Food and Drug Administration, as it takes months for the body to rid itself of mercury.

The danger from mercury is not just to developing brains. There is evidence to suggest an association between mercury exposure and heart disease, making it dangerous for everyone, but especially those who are already at risk.

The American Heart Association, however, recommends eating fatty fish at least twice a week because it is high in omega-3 fatty acids which are believed to help lower rates of heart disease, reduce hypertension, relieve some arthritis symptoms and prevent cancer. Fatty varieties that are low in mercury include herring, sardines, and wild salmon. Some popular fish that are also good choices include sole, tilapia, clams and oysters.

“It all depends on your diet — you can’t eat a lot of big, wild fish,” said Tim Fitzgerald, a marine scientist for Environmental Defense Fund, who provides health consumption information to Monterey Bay Aquarium’s Seafood Watch.

The problem with large, predatory species like marlin and swordfish is that they contain much higher levels of mercury than small fish, such as anchovies and sardines, because of the way mercury moves up the food chain. “Sharks, marlin, polar bears and people at the end of the food chain have the highest concentration of mercury,” Fitzgerald said.

It’s sometimes difficult for consumers to make seafood choices that are good for their health — and the environment. According to Tim Fitzgerald, “Billions of pounds of imported fish come into the United States annually, and less than one percent is tested for environmental toxins by the FDA.” Because marlin is not a popular dining choice in the U.S., many people are not aware of this. And while the FDA is the regulator body that creates consumer advisories about mercury for pregnant women, they actually do very little testing for this neurotoxin.

Another problem with the advisories is that they are not terribly specific and there’s a lot of room for interpretation, according to Fitzgerald. It’s also difficult for consumers to make the best seafood choices because sometimes what’s best for the environment is not always best for their health, and vice versa. For example, blue marlin and striped marlin from Hawaii are fairly resilient to fishing pressure and are listed as “good” alternatives for the environment on Seafood Watch. But, Seafood Watch also lists a health advisory for these fish, due to high levels of mercury. Monterey Bay’s other regional pocket guides provide further guidance for consumers and note that imported blue marlin and striped marlin should be “avoided.”

So, for U.S. consumers, the situation is “buyer beware — eat with caution,” but certainly not to give up on all fish. Consumers may just need some help from Monterey Bay’s Seafood Watch, which maintains a list of “which seafood to buy and why,” including a comprehensive seafood search, regional seafood guides — and printable pocket-sized guides for your wallet.

And, if you are a tech-savvy-seafood-lover, a “fish phone” may be more of what you’re looking for. Environmental Defense Fund’s Seafood Selector to-go allows mobile web users to look up their seafood guide on a blackberry or iPhone and download the information.

Ultimately, it’s ideal to exercise moderation and caution when eating seafood by taking into account both environmental and health concerns. Fortunately you don’t have to wonder whether the seafood menu at your favorite restaurant is environmentally friendly, the answers to your questions may just be a text-message away.