fishes, other sharks, skates, stingrays, sea turtles, molluscs, crustaceans, seabirds and even dead whales. Larger white sharks dine mostly on pinnipeds—seals and sea lions—and occasionally on small cetaceans such as dolphins and porpoises
pups to 3.6 feet (1.1 m) and adults to 21.5 feet (6.5 m), with females generally larger than males
mako, porbeagles and salmon sharks; Family: Lamnidae
continental shelf waters of temperate seas and oceans, sometimes venturing into the tropical zones; anywhere from the surface to depths of 4,200 feet (1,280 m)
The white shark is the Earth's largest predatory fish. This species has successfully thrived for more than 11 million years, with its immediate ancestors dating back more than 60 million years.
White sharks use quick bursts of speed to ambush their favorite prey: seals and sea lions. But adults also feed on the carcasses of dead whales, as well as occasional fishes, rays or smaller sharks. They're highly migratory animals, found throughout the world's ocean. White sharks have an array of keen senses—including organs that can detect the faint electrical fields given off by the bodies of potential prey. Adults can maintain a body temperature up to 15 degrees C warmer than the surrounding water. This is due to their large mass and a highly developed heat exchange function in their circulatory system that prevents heat from escaping as blood circulates through their gills and near the body surface.
In Monterey Bay
Monterey Bay is the seasonal home to adult white sharks, which return to California in late summer and early fall after spending months offshore in waters as far west as Hawaii. The sharks gather to feed when naïve juvenile elephant seals assemble together and haul out in colonies along the Central Coast.
In years when ocean conditions bring warmer waters into the bay, there are also sightings of younger white sharks—animals with a smaller body mass than the adults which don't do as well in the typically colder waters found north of Point Conception. These younger sharks are making the transition from a juvenile diet of skates, rays and schooling fishes to the marine mammals, like seals, that are the main food of adult white sharks.
Despite popular perceptions of sharks as invincible, shark populations around the world are declining because of overfishing, habitat destruction and other human activities. Of the 465 known species of sharks, 74 are threatened with extinction and another 210 species cannot yet be assessed due to lack of data, according to the International Union for the Conservation of Nature (IUCN). White sharks may be the top predators in the sea but they are highly protected due to their danger of being depleted.
While over 100 nations fish for sharks, only a handful have enacted regulations to protect them. Most white shark research and conservation groups are located in places where the population of white sharks is highest—off California, Mexico, South Africa and Australia. These regions, as well as U.S. waters off the East Coast and Gulf of Mexico, have laws that protect white sharks from either harassment or killing and the prohibit the sale of body parts.
In October 2004, white sharks gained new protection in a global wildlife treaty approved by the U.N.-affiliated Convention on International Trade in Endangered Species (CITES). The 166 member countries in CITES approved regulations requiring a controlled system of permits for all international trade in white shark parts and products. Under the new regulations, trade is closely monitored, and may be banned altogether if white shark numbers keep fading.
Shark finning, the practice of removing fins from a shark and then discarding its body, sometimes still living, back into the ocean is another threat. Up to 100 million sharks are killed worldwide for fins each year, primarily to meet the demand for shark fin soup. Fortunately, states and countries worldwide are banning this practice. In 2011, an Aquarium-sponsored bill was enacted in California with tremendous public support, banning the trade of shark fins. Since then, several other states have enacted similar laws.
- White sharks, along with some other shark species, store energy in their livers, similar to the way whales store energy in their blubber. The livers become enlarged with rich oil as the white sharks gorge on seals off California. In the winter the sharks tap into these reserves to propel their vast migrations, swimming up to 2,000 miles (3,219 km) non-stop across the Pacific.
- White sharks off California and Mexico annually converge in an area considered the desert of the Pacific. This vast and seemingly empty ocean expanse halfway between California and Hawaii is known to researchers as "The White Shark Café." Nobody is certain whether this is a feeding ground or an area where white sharks meet for courtship.
- Although capable of swimming across ocean basins, white sharks, like salmon, return to their native waters to give birth. As a result, populations of white sharks around the Pacific have become genetically isolated from each other. For example, even though white sharks can and do sometimes traverse ocean basins, white sharks off California have not interbred with those off New Zealand, or a third group off Japan, for around 200,000 years.
- A recent study by Stanford University and the Aquarium has documented that your chance of being attacked by white sharks in California has decreased by 90 percent in the past 50 years. While enjoying California's wild ocean is definitely safer today, it's still unclear whether this is because there are fewer white sharks off our coast, or the result of a change in the shark's behavior. The recovery of seal and sea lion populations in California from near extinction in the 1970s may be drawing sharks away from populated beaches and toward large seal rookeries along more isolated stretches of the coast.