How Sharks Form Social Bonds—and Why It Matters

The Lone Predator Myth

Few animals carry a more fearsome reputation than the shark. Decades of films and nature documentaries have cemented the image: a solitary apex predator, driven by instinct alone, roaming the ocean in isolation. But a growing body of scientific research is dismantling that picture, revealing creatures with surprisingly rich and complex social lives—ones that form lasting bonds, choose specific companions, and learn from peers.

Six Years of Watching Bull Sharks Make Friends

The clearest recent evidence comes from a landmark six-year study at the Shark Reef Marine Reserve in Fiji, published in the journal Animal Behaviour in 2026. Researchers from the University of Exeter, Lancaster University, the Fiji Shark Lab, and Beqa Adventure Divers tracked 184 bull sharks across three life stages: sub-adults, adults, and advanced-adults past reproductive age.

Rather than mingling at random, the sharks showed what scientists call active social preferences—consistently choosing specific individuals to spend time with while actively avoiding others. Lead researcher Natasha D. Marosi noted that bull sharks were "doing similar things" to humans, cultivating relationships ranging from casual acquaintances to close companions.

The team measured sociality in two ways: broad associations (sharks remaining within one body length of each other) and fine-scale interactions such as parallel swimming and lead-follow behavior, where one shark closely trails another. Both metrics pointed to the same conclusion: these animals are deliberately choosing their company.

Who Socializes With Whom—and Why

The data revealed clear patterns. Adult sharks formed the social core of the network, while younger sub-adults and older post-reproductive sharks were less integrated. Both males and females tended to associate more frequently with females. Males, though smaller than females in this species, maintained a wider range of social connections overall—a strategy researchers believe offers protection from aggressive encounters with larger individuals.

Size also mattered: sharks preferred to associate with others of similar body size, likely because comparably sized animals share the same dietary needs and face the same predators. Professor Darren Croft of the University of Exeter summarized the findings simply: bull sharks "have relatively rich and complex social lives," with potential benefits including skill acquisition, locating food, finding mates, and minimizing confrontations.

Bull Sharks Are Not Alone

This research builds on a broader pattern seen across shark species. Studies of lemon sharks (Negaprion brevirostris) at the Bimini Biological Field Station in the Bahamas showed that these animals form social groups called shivers and actively seek companionship—spending more time near other sharks even when there was no survival advantage for doing so. Lemon sharks also display social learning: untrained individuals who observed a peer successfully completing a food-reward task performed it with greater accuracy than control groups, as documented in the journal Animal Cognition.

Meanwhile, research highlighted by Oceana found that sand tiger sharks form complex social networks more commonly associated with mammals, maintaining relationships with dozens of individuals across seasons. Some individuals sustain what researchers describe as "best friend" relationships—animals they encounter repeatedly over the course of a year.

Why Sociality Evolves—and What It Costs

Evolutionary biologists explain shark sociality through cost-benefit logic. Being social can help animals find food faster, share knowledge about safe routes or productive hunting grounds, and gain protection in numbers. For male sharks that are physically smaller than females, alliances may offset vulnerability. But group living carries risks too: close contact increases exposure to parasites and disease, creating evolutionary pressure that keeps sociality in check rather than becoming universal.

What This Means for Conservation

Understanding shark social structure has direct practical consequences. When a population is heavily fished, removing socially central individuals—those with the most connections—can destabilize the entire group network far more than removing peripheral animals. The Fiji Shark Lab is already working with Fiji's Ministry of Fisheries to apply social network analysis to conservation planning, using the map of shark relationships to design more effective protections.

The broader lesson is about perception. Sharks have long been managed and feared as interchangeable solitary hunters. The science increasingly suggests they are individuals with preferences, relationships, and social knowledge—a reframing with implications not just for how we study them, but for how seriously we take their protection.