Great white sharks are found in coastal and offshore waters across the major oceans, preferring temperate regions. Their movements and habits are influenced by environmental and biological factors, providing insight into why they may be observed near human activity.
Factors Drawing Sharks Near Shore
The primary reason great white sharks approach coastal areas is the availability of their preferred prey. These powerful hunters primarily feed on marine mammals such as seals and sea lions, as well as certain large fish species. These prey animals frequently inhabit nearshore environments for feeding, breeding, or resting, creating attractive hunting grounds for the sharks.
Water temperature plays a significant role in their distribution, as great white sharks thrive in temperate waters ranging from approximately 12 to 24 degrees Celsius (54 to 75 degrees Fahrenheit). Warmer, shallower coastal waters can be particularly appealing, especially for juvenile sharks, who often seek out coastal nursery areas. Their unique physiological adaptations, including a degree of warm-bloodedness, allow them to maintain a body temperature higher than the surrounding water, enabling them to inhabit cooler waters than many other shark species.
Great white sharks also undertake seasonal movements, often following prey migrations or responding to changes in water temperature. These migrations can bring them closer to shore at specific times of the year, and some individuals return to the same locations annually. Additionally, certain underwater features, such as canyons, channels, drop-offs, and reefs, can serve as natural travel corridors or ambush points, influencing their coastal presence.
Typical Nearshore Habitats
Coastal areas supporting large colonies of seals and sea lions are recognized as prime hunting grounds for great white sharks. Locations like Seal Island in South Africa or the Neptune Islands in Australia are well-known aggregation sites due to the concentrated food source.
Estuaries and bays can also attract great white sharks, particularly juveniles, due to abundant fish populations or serving as nursery areas for various marine life. For instance, the Southern California Bight and parts of the New York Bight have been identified as important nursery grounds where young sharks congregate. Complex underwater structures like rocky reefs and kelp forests offer both cover for sharks and a diverse array of marine life, including their prey.
While less common for prolonged stays, great white sharks do patrol shallow waters near beaches. Observations have shown sharks within 50 to 100 yards of where waves break, and sometimes even closer. Their presence in these very shallow areas is often transient, as they move through or investigate the presence of prey.
Understanding Encounters
Despite great white sharks frequently coming close to shore, human encounters, particularly aggressive ones, are statistically rare. Humans are not a preferred food source for these sharks, and bites on people are uncommon, typically numbering fewer than ten globally each year.
One widely accepted explanation for the rare instances of shark bites on humans is the “mistaken identity” theory. From a shark’s perspective below the surface, a surfer on a board or a swimmer may resemble a seal or sea lion, which are common prey. Sharks possess relatively poor visual acuity and may use their mouths to investigate unfamiliar objects, leading to an exploratory bite.
To minimize the risk of an encounter, beachgoers can adopt several precautions:
- Avoid swimming at dawn or dusk.
- Avoid murky water.
- Stay away from known seal colonies.
- Avoid areas with active fishing.
- Swim in groups.
- Do not wear shiny jewelry, which can resemble fish scales.
- Consider darker colored swimwear, as sharks may have monochromatic vision.
If a great white shark is sighted:
- Remain calm.
- Avoid sudden, erratic movements or splashing, which could signal distress or mimic prey.
- Maintain eye contact and slowly exit the water.
- If possible, create a barrier with a surfboard or other equipment.
- Alert lifeguards and others in the water.