From Forbes, 18 March 2026 by Melissa Cristina Marquez
Why did it take us this long to figure this out? Well, studying shark behavior in the wild is not easy. The ocean is vast, visibility is often poor, and interactions can be fleeting. That is part of why social behavior in sharks has remained so elusive. As the researchers put it, understanding how and why marine species form social relationships is a fundamental goal in ecology and conservation, but one that comes with significant logistical challenges. Sharks do not exactly make it easy for us. To get around this, researchers turned to a unique location: the Shark Reef Marine Reserve in Fiji. This protected area is known for its regular aggregations of bull sharks, creating a rare opportunity to observe the same individuals over time instead of relying on brief, one-off encounters. Over six years, the research team identified individual sharks using scars, fin damage, and subtle differences in coloration. When those features were not enough, they used small identification tags placed just below the dorsal fin, allowing the team to follow specific sharks across years rather than days.
The researchers logged more than a thousand associations and social interactions, then compared those patterns to what you would expect if sharks were simply bumping into each other by chance. If bull sharks were truly solitary, their interactions should look random, shaped only by proximity and opportunity. Instead, clear patterns emerged. Some sharks preferred certain individuals. Others seemed to avoid each other. To quantify this, the team looked at behaviors like swimming in parallel, following one another, or joining and then turning back, all of which painted a picture of intentional interaction. It is tempting to call these relationships friendships. The researchers are more cautious, but the comparison is hard to ignore. Like humans, these sharks appear to maintain a range of relationships, from frequent associates to individuals they keep their distance from. That alone challenges the idea that sharks are purely asocial animals.
When asked how she felt when she realized what she had discovered, the study’s lead author Natasha D. Marosi, a researcher at Exeter University said, “I was absolutely elated and I felt validated. I had been diving with these bull sharks for years and had observed so many remarkable behaviors and saw ‘friendships’ that can no longer be dismissed as ‘anthropomorphizing.’ […] I was so excited to share our findings and dispel our traditionally held beliefs about the solitary nature of the bull shark. ”
Dig a little deeper, and the picture becomes even more interesting. Female bull sharks were more likely to associate with other females, forming tighter social clusters. Males, on the other hand, showed a preference for females as well, though those interactions were less common because the females were not as interested in reciprocating. Marosi and her team believe there may be practical reasons behind this — female bull sharks are larger, and associating with them could provide males with better access to food or reduce the risk of aggression within the group. And size and age also played a role, it seems! Sharks tended to associate with others of a similar size, which may reduce conflict or make coordination easier. Younger sharks appeared to be more social overall, forming more connections within the network. As they aged, that sociability declined.
But why would that happen? One possibility is experience. Younger sharks are still learning how to navigate their environment, find food, and avoid threats, including other sharks. Social connections could provide valuable opportunities for learning or reduce risk through safety in numbers. “The sub-adults we see in our adult aggregation that socialize with adults gain valuable access to the aggregation through their ‘big brother’ or ‘big sister’ and likely are learning from them as well,” explained Marosi, who also founded Fiji Shark Lab, noting that sub-adults were not common in their adult aggregation and “that to even be [there] they represent a bolder subset of their age group.” Older sharks, by contrast, may not need that support. With years of experience behind them, they may rely more on their own knowledge than on social ties.
This perceived shift raises an interesting question: If sociality changes across a shark’s life, how important is it at different stages? And what happens if those social structures are disrupted? This is where conservation come into the equation (as it usually does, and should). Shark Reef Marine Reserve is also a site where sharks are provisioned, or fed, during ecotourism dives. A controversial practice as, on one hand, it supports local economies and fosters appreciation for sharks but it may also alter natural behavior. Our activities might disrupt these groupings; for example, fishing pressure might remove key individuals from a social network that could affect how younger sharks learn or how groups access resources. And losing them could ripple outward in ways we have not considered. While we often think about conservation in terms of numbers (e.g., how many sharks are left, how many are caught, how many are protected). But studies like this suggest we may also need to see these animals as part of a network.
Bull sharks are not alone in this. Evidence of social preferences has been found in other species, including reef sharks and lemon sharks. Contrary to belief, sharks are animals capable of complex social behavior. And once you start to accept that, it becomes a little harder to see them as interchangeable, faceless predators moving through the ocean. It is one thing to say that shark populations are declining globally due to overfishing, habitat degradation, and bycatch. It is another to realize that the loss of even a few individuals could have cascading effects on a social network we barely understand. For many people, supporting shark conservation can feel overwhelming. The problems are large, the ocean is vast, and the solutions can seem out of reach. Most of us will never meet a bull shark, let alone recognize one individual from another the way researchers do. But one of the most effective ways to make these issues tangible is by connecting people directly to the animals scientists are studying. “One of the most important takeaways from this research is that sharks have far richer social lives than we once assumed, and understanding those social systems helps us implement more effective protection measures. Through Fiji Shark Lab, we invite people to support this work by adopting one of the sharks from our study population,” says Marosi. “Those adoptions directly help fund our research and conservation initiatives in Fiji.”
Conservation has always been as much about people as it is about wildlife. And public support often hinges on whether people feel a connection to the species in question. Sharks have historically struggled in that regard. But research like this chips away at that narrative, showing us that sharks, while very different from us, are not as distant as we once thought. Maybe that’s enough to take us down a new path to co-existing with these remarkable animals.
