For the first time, tiger sharks have been photographed near Easter Island in the South-East Pacific. While there have been anecdotal reports of tiger sharks in this region before, this is the first time such sightings have been documented scientifically.
A curious tiger approaches a diver (own image)
The sightings, documented in a study by Amy Rose Coghlan and Naiti Morales, took place during a period of unusually warm sea surface temperatures, a condition that has been linked to the expansion of tiger shark habitats in other parts of the world.
These new records, along with historical data, are crucial for understanding and predicting how species like the tiger shark adapt to their environment, including their migratory patterns and the limits of their range. This is especially important in light of the swift changes taking place due to global warming.
Migration
Tiger sharks are highly migratory and can travel vast distances across the oceans. Some individuals have been tracked moving thousands of kilometres from one region to another. Their migrations are typically influenced by water temperature and prey availability.
In some regions, tiger sharks migrate seasonally. During the winter, they migrate from cooler temperate waters to warmer tropical and subtropical waters. Their appearance in the vicinity of Easter Island may, therefore, be due to global warming and the expansion of warm seas.
Ecology
Tiger sharks often travel between coastal areas and the open ocean. They are commonly found near coral reefs, estuaries and bays. Female tiger sharks frequently use shallow coastal areas as nursery grounds where their young can grow with less risk of predation. But tiger sharks have also been spotted far offshore, sometimes in deep waters.
As apex predators, tiger sharks play a crucial role in maintaining the balance of marine ecosystems. They are generally solitary and hunt alone, especially at night when they are most active. They use their keen sense of smell and electroreception to locate a wide variety of prey, including fish, sea turtles, seabirds, and seals. They sometimes consume inedible objects like license plates and tyres.
As is also true of other shark species, they are curious animals. They often investigate objects or animals in their environment, and this curiosity sometimes leads them to approach boats or divers.
Threats to tiger sharks
The International Union for Conservation of Nature (IUCN) lists tiger sharks as Near Threatened. They face threats from industrial and recreational fishing, both of which are now strongly influenced by the lucrative shark fin trade and habitat loss.
Understanding tiger sharks' migratory patterns and habits is vital for their conservation, as it helps scientists predict their movements and identify critical habitats that need protection. The sighting at Easter Island provides more information about their ranges and the effect of the expansion of warming seas.
