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There are about forty species of sharks of the 450 species of fish that occur in (i.e., are endemic to) Hawaiian waters, ranging in size from the deep-water Pygmy Shark (Squaliolus laticaudus - about 8 inches) to the Whale Shark (Rhincodon typus - up to 50 feet or more).
White Tip Reef Shark
About eight species are commonly seen near shore. The most frequently encountered arethe Sandbar, Reef Whitetip, Scalloped Hammerhead, and occasionally Tiger. These inshore species are top-level carnivores, feeding primarily on fishes. Their function in reef ecosystems is not fully understood, but they are believed to improve fish populations by removing sick and injured fish, leaving the healthiest to reproduce.
Sharks have extremely well-developed sensory capabilities. They can detect sounds and and smells from prey at great distances (up to two miles or more, depending on water conditions). Their eyesight is good, but depends greatly on water clarity. As sharks approach their prey, they can detect the faint electrical fields give off by all living organisms. Receptors on their snouts, known as ampullae of Lorenzini, allow sharks to locate their prey without seeing it. Using these senses, sharks can find prey at dusk, night and dawn, which is when inshore species are generally believed to feed.
Sharks are very well aware of their environment and appear to be fairly curious by nature. They are aware of people in the water before people are aware of them. Encounters between sharks and people are infrequent, and most inshore species pose little threat to humans.
While any shark may be potentially dangerous, only a few species of Hawaiian sharks are known to attack people. They include the Tiger, Galapagos, Gray Reef and Scalloped Hammerhead. The latter two appear to attack only when provoked. The Tiger and Galapagos are most aggressive.
A Tiger shark is easily recognized by its blunt snout and the vertical bars on its sides. A Galapagos shark is harder to identify; however, any large (over six feet) gray shark with no conspicuous markings seen in inshore waters is probably a Galapagos. Tigers are considered the most dangerous sharks in Hawaiian waters. (Great White Sharks - Carcharodon carcharias, which are also very dangerous, are rarely seen in Hawai`i.) Because of their size and feeding habits, they occupy the very top niche in inshore food chains.
Tigers seem to come into inshore waters in Fall, and stay through Spring. They appear to move offshore somewhat in Summer, but this remains to be confirmed. Like other inshore species, Tigers seem to feed mostly during night and twilight hours. Tigers are often attracted to stream mouths after heavy rains, when upland fishes and other animals are swept out to sea. They can easily locate prey in such murky waters. Tigers are also attracted to waters frequented by fishing boats, which often trail fish remains and blood.
Of all the inshore species, Tigers have the most widely varied diet. They eat fish, lobsters, birds, turtles, dead animals, even garbage. It's not known how long Tigers can go without eating, but they soon seem to feed whenever a food source is present. It's also not known why Tigers sometimes attack humans. A Tiger may mistake a person for a prey item, it may come across a person while in a feeding "mode," it may be trying to see if the person is prey, or perhaps there is some other explanation.
Divers who may encounter sharks often carry a shark billy or a bang stick. A billy is a club used to fend off a shark by hitting it on the snout. A bang stick is a rod with an explosive charge at the tip, used to kill an aggressive shark. Bang sticks are effective, but very dangerous. In addition, the resulting blood may attract other sharks.
Shark attacks in Hawaiian waters are very rare, occuring on the average at a rate of about two or three per year. Surfers and spearfishers appear to be most at risk. Fatal attacks are extremely rare, especially considering the number of people in Hawai`i's waters. People who enter the water need to recognize that there are hidden dangers, and sharks are just one of them. By learning more about sharks, and using common sense, the risk of injury can be greatly reduced.
Famous North Shore Shark Adventure
As featured on ESPN Outdoors and BBC Outdoors in England, North Shore Shark Adventures, Hawaii's original shark tour company, provides an intimate and thrilling experience with Hawaii's sharks. Don't miss this once-in-a-lifetime encounter! Your adventure begins with a short 15-minute boat ride that will take you three miles out from Haleiwa Small Boat Harbor. You'll take in the breathtaking views of Oahu's North Shore and may even encounter dolphins, green sea turtles, or majestic humpback whales (December-May).
When the water turns a deep cobalt blue and reaches depths of 200-400 feet, the shark cage, which floats on top of the water, is lowered and in only a moment's time you will see sharks rise from the deep! At this point, you'll have the opportunity to enter the very secure shark cage for as long as you wish (those in your group who do not wish to enter the shark cage, may book the half-price observer rate, and watch you from the boat). This thrilling experience will profoundly affect your feelings towards sharks. Typically you will encounter Gray Reef Sharks, Galapagos Sharks, and Sandbar Sharks, ranging from 5 to 15 feet in length. Occasionally, there have been visits from the mysterious Tiger or Hammerhead Sharks! North Shore Shark Adventure