What the Surfer Should Know about Sharks

Most surfers associate sharks with Australia, and rightly so. In the past 150 years there have been 200 documented attacks there. But sharks are found nearly everywhere, in almost every latitude. True, most sharks prefer temperate and tropical seas, but one species—the Greenland Shark—is found in Arctic waters. Interestingly enough, not all shark victims have been in the ocean at the time. Sharks have been reported great distances up rivers, attacking pilgrims in the Ganges, and Iranians in a river 90 miles from the sea. Here a British ambulance driver nearly lost a leg as a result of a shark attack, while standing in a river only one foot deep!

There are usually no less than a dozen reports of shark attacks annually. World-wide in 1959, the last year for which reports are available, there were 36 such attacks, 13 of which were fatal. Of the 36, ten occurred in the U.S. with three fatalities.

Although there are 250 species of shark, only about 30 warrant the title of killer, ranging in size from about 5 to 25 feet. Probably the most dangerous is the Great White Shark, which sometimes may weigh close to four tons. Its deep-water relative, the Mako, is extremely fast and a spectacular fighter. For this reason, he is highly regarded as a game fish.

Among the largest of the killers is the widely distributed striped and appropriately named Tiger Shark. He menaces both Australian and Caribbean waters. Smaller types include the Lemon, Leopard (common to Southern California) and their open-sea relatives, the Blue and the White-Tipped shark. Contrary to the popular belief that because of the weird and cumbersome head shape it is not a man-eater—the truth is that the Hammerhead Shark can be extremely vicious. To dispel any doubts about this, it should be pointed out that the first recorded fatal shark attack in American waters was caused by a Hammerhead off Long Island, New York, in 1815.

Sharks like the Dogfish, common in East Coast waters, have never been implicated in attacks on swimmers. Two species, the Basking Shark and the Whale Shark, are harmless even though they are the largest creatures in the sea next to whales. They reach lengths up to 60 feet, but feed on plankton and are unequipped to attack man.

The shark is an undiscriminating predator, often a scavenger, and essentially an opportunist in feeding, with rather remarkable specializations for predacity. Sharks have highly developed olfactory organs (sense of smell) which enable them to detect blood, or the scent of dying fish, hundreds of yards away. Sharks can smell both living and dead prey. In open water, sharks will converge on water siphoned from a container in which there are frightened but uninjured fish. This suggests that the distressed fish give off some substance, perhaps a metabolite, in sufficient quantity to attract the sharks.

Though people have been warned not to wear brightly colored swimsuits, especially orange, which might attract sharks, it is believed that sharks are color-blind due to the almost complete absence of color-sensitive cells in the retina. However, the shark appears to have the ability to discriminate between red and white. This is probably due to a difference in the shades of gray, or degree of brightness, rather than color. The eyes of most sharks are adapted for vision in either bright or dim light, the mechanism of reflection being common to most predators, particularly members of the cat family.

By experiment, it has been determined that at distances greater than 100 feet, smell is more important than vision in guiding sharks to prey. Under 100 feet, depending on the amount of light and clarity of water, vision increases in importance, and at less than 10 feet it is the principal guiding sense.

Sharks have tiny brains and skeletons of cartilage. Because they lack the swim bladders found in bony fish, they must keep moving to keep from sinking. Therefore they have larger fins and tails than other fish. They sink like stones when they die.

The general tendency for all fish feeding is for the predator to attack when his prey is feeding or at a disadvantage, such as small fish in a strong current over a reef. The shark is no exception. All fish show considerable curiosity and are attracted to unusual movement in the sea.

The strength of a shark’s jaws and teeth is enormous; steel hooks 1/12 of an inch thick are sometimes bitten through. Moreover, shark teeth are loosely set in rows, so that as the front teeth become worn or break off, replacements gradually work up from behind.

When feeding in groups, sharks may quickly devour a disabled fish. But the predators, feeding leisurely, will take 20-lb. bites of a big fish, carefully avoiding tough fins and bony parts. Five bites can take practically all the good meat from a 120-lb tuna. A big shark may swallow a 40-lb. fish whole. Shark bites have an unmistakable crescent-shape and are often so deep that a major artery is severed. Many victims die of blood loss before they can be brought to shore.

It is to be noted that satiation plays a role of no great importance in sharks. Despite their ferocity, sharks are undiscriminating scavengers, swallowing anything: sea turtles, sea lions, birds, fish, garbage, tools, people, etc. They just bite and swallow, and can apparently store food for days and weeks without digesting it. It was this very characteristic which led to the solution of the sensational Shark Murder Arm Case. In 1935, a big tiger shark was caught and featured in an aquarium in Sydney, Australia. Eight days later, it disgorged a human arm so well-preserved that a tattoo on it was identified, leading to the eventual conviction of the man’s murderers!

Probably one of the most widely held misconceptions about sharks, is that they always roll over on their sides to attack. Some sharks do, sometimes, but no shark has to. Nor do they have to make their attacks from the surface. It has been well established that sharks swim up to their prey and in a deliberate manner set their teeth, and then shake their heads violently until they tear out a chunk of flesh. This deliberation is quickly lost, however, during a “feeding frenzy” in which the sharks, aroused by the smell of blood, attack anything, including each other.

One of the world’s experts on sharks believes that once having tasted human flesh, sharks may acquire an appetite for it. The shark menace has led to many devices and procedures to eliminate them. One shark repellant, known as Shark Chaser, developed during the Second World War, was rather doubtful in its effectiveness, as sharks were observed to gobble up the packets as fast as they hit the water.

Nigrosin dye, which spreads a black cloud in the water, has been effective, probably by obscuring the swimmer. Recent experiments show that human sweat in concentrations of one-part per million, has repellant properties. But no repellant has proved effective during the feeding frenzy.

Played down as cowardly in the World War II Navy Manual, it was stated that sharks will be frightened by shouting or a stout blow on its sensitive snout. It seems the former would be just as likely to attract them, and the latter would most likely make him angry, not to mention the probability of cutting yourself on his rough hide, thereby arousing this swimming appetite even more, with your bleeding.

In conclusion, it would seem that if one is liable to find himself swimming in the company of sharks, possibly as good protection as any would begin on land: avoid soap and deodorants. Your friends may avoid you—but then, possibly, so will the sharks.