A unique underwater cafe
In Indonesia's Cenderawasih Bay, a strange and wonderful interaction occurs daily. In this bay, the planet's largest fish, the whale shark (Rhincodon typus), gathers around traditional lift-net fishing platforms known as 'bagans'. Fishermen on these wooden structures use powerful lights at night to attract schools of small baitfish, which they then haul up in large nets. The whale sharks, drawn by the scent and commotion, have learned a remarkable behavior. They approach the bagans and suck directly at the nets, slurping up escaping baitfish, or simply wait for fishermen to hand-feed them.
This learned feeding only happens in Cenderawasih Bay. The local fishermen, who have been using bagans since the 1950s, believe the sharks bring good luck and willingly share their catch. This creates a reliable, year-round food source for the sharks, turning the bay into an unparalleled natural laboratory for studying a species that is otherwise highly migratory and elusive. The interaction allows scientists a rare, close-up look at these gentle giants, which can grow up to 18 meters long.
A scientific anomaly
The Cenderawasih Bay aggregation presents a scientific puzzle. Unlike other known whale shark hotspots, which are typically seasonal and attract a mix of individuals, the population here is overwhelmingly composed of juvenile and sub-adult males. A comprehensive 13-year study identified 268 individuals, revealing a male-to-female ratio of nearly 9 to 1. Most of these sharks measure between 3 and 8 meters in length, suggesting the bay acts as an important nursery or feeding ground where young males can grow.
Many of these sharks stay in the area. Satellite tagging studies have confirmed that while some individuals undertake long migrations, a significant portion of the population exhibits long-term residency in the bay. Re-sighting data shows some sharks have been present in the area for over a decade. This unusual, non-migratory behavior is likely linked to the constant food supply from the bagans. The International Union for Conservation of Nature (IUCN) lists the whale shark as an Endangered species, with global populations declining by over 50% in the last 75 years. This makes the predictable and accessible Cenderawasih population exceptionally important for global conservation and research efforts.