The tiger shark (Galeocerdo cuvier) is one of the ocean’s largest predatory sharks, reaching lengths between 10 and 14 feet and weighing over 850 pounds. This formidable size and its reputation as a generalist predator establish it high on the marine food chain. Despite its standing as a near-apex predator in tropical and subtropical waters, the tiger shark is not without risks of being preyed upon. What eats a tiger shark depends primarily on whether it is a fully grown adult or a vulnerable juvenile.
Primary Natural Predators of Adult Tiger Sharks
The list of animals capable of successfully preying on a healthy, mature tiger shark is short, with the primary contender being the orca (Orcinus orca), also known as the killer whale. Orcas are marine mammals that often hunt cooperatively in pods, employing strategic methods to overcome large prey. They target large sharks, including the tiger shark, due to their rich, calorie-dense livers.
Orca predation often involves isolating the shark and ramming it with powerful force, which causes internal injuries. A tactic observed in orcas is flipping the shark onto its back, inducing a catatonic state known as tonic immobility. Once the shark is incapacitated, the orca precisely targets the liver, leaving the rest of the carcass behind.
The only other creature with the size and capacity to challenge a full-grown tiger shark is the great white shark (Carcharodon carcharias). While interactions are rare and often based on competition, confrontations may occur when their territories overlap. These two large species generally occupy different ecological niches, but the larger or more aggressive individual has the advantage.
Predation Risks for Juvenile Tiger Sharks
While adult tiger sharks have few natural enemies, their offspring face a higher mortality rate from a diverse array of predators. Tiger shark pups and juveniles are vulnerable until they reach a substantial size of several feet. Their characteristic vertical stripes, which fade in adulthood, help to camouflage them in coastal nursery habitats.
Larger, mature sharks of different species are threats to young tiger sharks. Bull sharks (Carcharhinus leucas), hammerhead sharks (Sphyrna spp.), and other large requiem sharks opportunistically prey on smaller tiger sharks. Cannibalism, where larger individuals of the same species prey on smaller ones, is also a recognized risk for the young.
Juvenile sharks often seek shelter in shallow coastal areas, such as estuaries and mangrove forests, which serve as protective nursery grounds. However, even within these habitats, they are not completely safe from predation by large bony fish and other opportunistic feeders.
Other Factors Influencing Tiger Shark Mortality
The greatest threat to tiger shark populations, regardless of age, comes from human activity. Commercial and recreational fishing practices account for the vast majority of non-natural mortality. Tiger sharks are intentionally targeted for their meat, fins, and liver oil. They are also frequently caught unintentionally as bycatch in longline and gillnet fisheries. This overall fishing pressure has led to the species being classified as Near Threatened.
Mortality also occurs from intraspecies conflict and scavenging. While cannibalism is a known risk for juveniles, adult tiger sharks scavenge on the remains of deceased conspecifics. Injuries sustained from territorial fights, disease, or complications from ingesting marine debris like plastic and metal can contribute to the eventual death of a tiger shark.