Over a period of six months, Odyssea researcher Anna Schleimer joined the Large Marine Vertebrates Project in the Philippines to study the behaviour of the world’s largest fish: the wale shark. The project was located in the small town of Oslob on Cebu, which has become a popular destination for whale shark watchers since an amateur video in 2011 had shown fishermen luring whale sharks away from their fishing nets with food. Along with the growing number of tourists came changes in the local economy as the tourist industry created many new jobs in resorts, restaurants, scuba diving companies and tourist tours. Now many locals rely on whale shark tourism as their primary source of income. When talking to locals, you soon realise how proud the community is about their ‘butanding’, the local term for whale shark, and that they care about their whale sharks.

However, the whale shark aggregation in Oslob is maintained through provisioning, a highly controversial method where the whale sharks are being fed by humans to create an incentive for the animals to stay in the area. Possible consequences of provisioning include the disruption of natural behaviour, aggressive behaviour towards humans, and increased stress levels. In order to understand how provisioning is affecting the whale sharks of Oslob, researchers and volunteers from the Large Marine Vertebrates Project spent hundreds of hours in water to study and document the behaviour of the provisioned whale sharks in Oslob. By taking pictures of the spot pattern on the sharks (photo-identification), the researchers were able to recognise individual whale sharks and describe changes in their behaviour over time.  The study showed that the sharks had learnt to associate the area with food and that frequently returning sharks had synchronised their arrival to the feeding area with the schedule of the feeding boats, both arriving around 6 am every morning. The researchers also noticed that the whale sharks changed the way they fed over time: while initially the new sharks swam around hectically, with some experience they learnt to approach the boats with the feeders providing little handfuls of shrimp. Experienced sharks were often observed in a stationary vertical position engulfing the food next to the boats. The study also revealed that frequently returning sharks became less skittish over time and reacted progressively less to touches from other sharks and tourists (which were documented despite a no-touch policy).

In addition to the animal behaviour, researchers also recorded compliance to the code of conduct, particularly whether regulations on the minimum distances between swimmers and whale sharks and the maximum number of people allowed per whale shark were followed. The study clearly showed that overcrowding was the norm and that people were not respecting the minimum distance limits to the sharks. That is why a stricter enforcement of the code of conduct is required in order to prevent potentially negative impacts on the animals.

While this study clearly showed that provisioning lead to changes in behaviour of the whale sharks, it remains unclear to what extent the observed changes reflected a mere adaptation to increase feeding efficiency or an actual disruption of natural behaviour. Oslob is currently the only place in the Philippines where an artificial whale shark aggregation is maintained through provisioning. Donsol and Southern Leyte are known to have natural seasonal aggregations of whale sharks (no provisioning) and should be considered as an alternative to Oslob.

The full study can be found here: https://peerj.com/articles/1452.pdf