An incredible example of nature fulfilling the old adage of there being safety in numbers, bait balls are a natural defence mechanism used by small schooling fish – such as sardines, anchovies, and mackerel – when they are under threat from predators.
The fish cluster into dense, spherical formations to confuse and deter attackers and, in the process, create one of the most dramatic spectacles in the ocean.
When a predator approaches, the small fish respond to its presence by tightly packing themselves into a swirling mass, often shimmering as light reflects off their scales.
The theory goes that individual fish have more chance of survival as a group than they do as an individual. However, the bait balls also attract more predators due to its concentrated nature.
Sharks, in particular, are drawn to them as they offer an abundant and accessible food source. They will utilise their speed and agility to penetrate the bait ball, snapping up fish in swift, precise movements.
Sharks even collaborate with other predators, working in groups to drive bait balls toward the surface or corner them against natural barriers like coral reefs. In some instances, this intense feeding behaviour can escalate into a “feeding frenzy,” where multiple predators converge to exploit the opportunity.
Among some of the finest places in the world to witness this amazing activity when diving are Indonesia and the Maldives.
Komodo National Park, Raja Ampat, Alor, and the Banda Sea are all known for bait ball activity in Indonesia with good areas within Maldivian waters coming at, among others, Hanifaru Bay and Vaavu Atoll.
The best chance of seeing this phenomenon comes in nutrient-rich waters during strong currents. As plankton blooms it attracts large schools of fish and, in turn, predator activity increases with strong currents.
The incredible spectacle provided by bait balls and shark feeding showcases the intricate balance of oceanic ecosystems, highlighting both the survival instincts of prey and the hunting strategies of predators.
Observing this in the wild is a truly breathtaking experience as the drama of life beneath the waves unfolds in front of you.
Want to find out more? Have a look at our itineraries in Indonesia and the Maldives and pick one that will give you a great chance to see bait balls in action