It is the largest of the sharks and is found in all tropical seas, yet the whale shark remains enigmatic. There are still many mysteries about the behaviour and ecology of this gentle, plankton-eating giant. In the Pacific Ocean, there are whale shark research programmes in Taiwan, the Philippines, Mexico and the Galapagos. In the Eastern Pacific specifically, though, the species is poorly understood. Nevertheless, it is known to migrate very long distances – thousands of kilometres. And although the presence of whale sharks off the coast of Peru has been confirmed since 1955, until now these animals have not been studied. Dení Ramírez-Macías has been researching whale sharks off the west coast of Mexico – and in other parts of the world – for more than 10 years. Now she’s moving south to Peru. Dení would like to know whether the two countries’ whale sharks are the same individuals that are simply moving between different habitats. But finding out isn’t going to be easy; in six months she and her colleagues have seen only two whale sharks. This is despite receiving reports from local fishermen of a whale shark aggregation site.

Through her project, funded by the Save Our Seas Foundation during 2014–2015, Dení aims to do baseline research on whale sharks in Peru to determine basic information such as seasonality, abundance and population structure – information crucial for conservation action. Monitoring the population is critical for appropriate management and to determine whether whale sharks have the potential to be a tourist attraction and offer an alternative livelihood for the fishing community.