Whale sharks down under
Every year, hundreds of whale sharks congregate at Ningaloo Reef in Western Australia. Lara wants to know why. She believes that the secret behind their annual visit is hidden in their stomachs.
Lara Marcus Zamora
I have been interested in the ocean for as long as I can remember. Growing up in Barcelona next to the beautiful Mediterranean Sea triggered my passion for unknown blue waters, and from childhood I dedicated my academic and personal life to becoming a marine biologist.
Although Spain has long coastlines, there was nowhere for me to fulfil my desire to learn more about the sea and its inhabitants, especially the large ones. So while an undergraduate studying biology, I took part in several marine expeditions and was lucky enough to dive...
Environmental and biological factors driving whale shark distribution and abundance
Investigate whale shark feeding ecology to gain a better understanding of their preferred prey and associated habitat.
Although it’s the largest fish in the world, the whale shark is also one of the least-studied shark species and its status is vulnerable. It is very important to gain new insights into the basic ecology of the whale shark in order to assist in the development of national and international management and conservation programmes.
The life history of the whale shark is poorly understood, and to date, even basic information on demography, migration pathways and feeding ecology is still lacking. Whale sharks aggregate seasonally in certain coastal waters throughout the world’s temperate and tropical seas, including Ningaloo Reef, Western Australia. The predictable, seasonal occurrence of whale sharks in certain locations supports two profitable industries: ecotourism and fisheries. While ecotoursim has provided highly valuable information on whale shark size, sex and population structure, fisheries have severly depleted whale shark biomass in some areas and there is evidence of decline in whale shark populations across much of the species’ range. The whale shark is considered Vulnerable according to IUCN Red List criteria. Given their life-history traits of slow growth and late age of maturation, any recovery after over-fishing would take many years.
Although very limited data exists concerning whale shark aggregations, it is believed that whale shark movements are associated with water conditions and abundance of their preferred prey. Based on coastal surface observations, whale sharks have always been described as pelagic filter feeders. However, a recent pilot study using a biochemical approach has revealed new insights into the whale shark’s diet. Given the succesful results obtained using biochemical techniques in other marine animals, we hope to further develop this approach specifically for the whale shark’s potential prey. Results from this work will clarify whale shark diet, and in turn, help us to understand their foraging range.
The general aim of this research is to study whale shark feeding ecology by determining the physical and biological factors influencing whale shark seasonal aggregations at Ningaloo Reef, Western Australia.
The specific objectives are to:
- Determine the diet of whale sharks
- Identify the foraging ecology of whale sharks in relation to their preferred prey and associated habitat
- Help to increase awareness of the whale shark’s Vulnerable status through communication of our research to stakeholders, the scientific community and the public
- Collaborate with the ecotourism industry to further develop whale shark monitoring and tagging studies in the Ningaloo Reef.