The Hawaiian Islands are surrounded by a marine environment that serves as habitat for a wide range of marine life, including sharks. The presence of these animals, known as mano in Hawaiian, is a long-established fact of the archipelago’s ecology. Over 40 species of sharks are found throughout the region, from shallow coral reefs to deep pelagic zones offshore. This article explores the most commonly encountered species, their behavior, safety measures for ocean users, and the profound cultural role sharks hold in the islands.
The Most Common Shark Species in Hawaiian Waters
The most frequently encountered sharks in Hawaii’s nearshore waters are reef-dwelling species and two larger coastal predators. White-tip Reef Sharks, which typically reach about five to six feet in length, are common and often seen resting motionless in caves or under ledges during the day. They are primarily nocturnal hunters that feed on fish, crustaceans, and octopus on the reef and are considered non-aggressive toward humans.
Another common resident is the Sandbar Shark, recognizable by its tall, triangular dorsal fin, which prefers coastal waters and sandy bottoms and grows to about six to eight feet long.
The Tiger Shark (Galeocerdo cuvier) is the largest and most well-known species, with adults often reaching 10 to 14 feet. These opportunistic feeders are known for the dark vertical stripes that fade as they mature, and they consume a varied diet including fish, sea turtles, and seabirds. Tiger Sharks are responsible for the majority of rare, serious incidents in Hawaiian waters. Scalloped Hammerhead Sharks (Sphyrna lewini) are also common, often seen in schools, and gather in large numbers in certain bays that serve as important nursery areas.
Understanding Shark Ecology and Movement Patterns
The geography of the Hawaiian archipelago, featuring deep-sea trenches and extensive shallow reef systems, supports both pelagic and coastal shark populations. Tiger sharks are known to navigate widely between the main Hawaiian islands, exhibiting extensive home ranges. Tracking studies reveal that female Tiger Sharks migrate from the remote Northwestern Hawaiian Islands to the more populated main islands in the late summer and fall. This seasonal movement is linked to their pupping season, where they seek shallower, protected nursery areas to give birth.
This seasonal influx of mature female Tiger Sharks coincides with the months that have historically recorded the highest number of shark incidents. Hawaiian oral traditions reflect this pattern, warning that the late summer and fall months, when the wiliwili tree blooms, correlate with an increased risk. Sharks are also drawn to certain nearshore habitats, such as river mouths, harbor entrances, and areas with steep drop-offs. After heavy rains, runoff can carry terrestrial animals and debris into the ocean, attracting opportunistic feeders like the Tiger Shark to the murky plume.
Assessing Risk and Essential Safety Guidelines
The risk of a shark encounter in Hawaii is extremely low, particularly when compared to other common ocean activities. On average, the state records fewer than ten unprovoked shark incidents annually, with fatalities being exceedingly rare. The majority of incidents involve surfers, reflecting the amount of time and activity they spend in the water. Despite the low overall risk, adopting specific safety practices can further minimize the chance of an encounter.
Ocean users should follow these guidelines:
- Avoid entering the water at dawn, dusk, and nighttime, as these are peak feeding times for many inshore shark species.
- Stay out of murky or cloudy water, especially near stream mouths or harbor entrances, because poor visibility increases the chance of a shark confusing a person for prey.
- Refrain from swimming alone.
- Do not enter the water if you have open wounds or are bleeding, as sharks can detect small concentrations of blood.
- Avoid excessive splashing and wearing high-contrast clothing or shiny jewelry, as these factors may attract a shark’s attention.
The Cultural and Ecological Significance of Sharks
In Hawaiian culture, the shark, or mano, is not merely a predator but a creature of deep respect and spiritual significance. Many native Hawaiian families consider the shark to be an ʻaumakua, a benevolent family guardian spirit or deified ancestor. These ancestor spirits are believed to take on physical forms, including the shark, to watch over their descendants and offer warnings of impending danger. This traditional connection fosters a sense of co-existence and protection, where certain sharks are individually identified and named.
From an ecological perspective, sharks are apex predators that play a role in maintaining the health of the marine ecosystem. By preying on the sick, weak, or injured fish, they help keep the fish population healthy and prevent disease from spreading. The presence of sharks assists in regulating the food web, from the shallow coral reefs to the open ocean, underscoring their importance to the biological balance of Hawaiian waters. This dual status highlights the complex relationship between humans and mano in Hawaii.