Secrets of the Galápagos whale sharks

Show notes

Welcome back to The Whole Tooth, a podcast all about sharks, rays and their underwater habitat! In the first episode of season 3, we are celebrating the world’s largest shark: whale sharks! There is much still to discover about these gentle giants, especially those who visit the Galápagos marine reserve. Jonathan and Sofía Green work on the Galápagos Whale Shark Project (GWSP), which aims to discover more about these incredible animals, their natural history, and their movements around the Galápagos.

Of course, we start by hearing about Jonathan and Sofía’s most memorable experiences (4.48). Prepare to be jealous. Jonathan’s experience involves listening to The Beatles’ ‘Yellow Submarine’ while 100m deep in a yellow submersible for Blue Planet II. Sofía’s story is about an exceptional encounter with a whale shark. She describes freediving with a female, attempting to take a blood sample when dolphins appear and start riding alongside! We also learn how Sofía’s love of sharks began in early childhood, as Jonathan would take her freediving to ‘shark pools’ to see white-tip reef sharks (14.00).

Jonathan then tells us how the GWSP came to be (15.59). While working as a guide and dive master for the Galápagos Marine Reserve and National Park, he encountered a whale shark for the first time. After discussing this with the community, he soon realised little was known about their natural history and relationship to the reserve and started asking fellow divers to collect basic data. It turned out that most of the individuals seen at the diving sites were females – 99.89% to be exact. This started the idea for the project, which officially began in 2005 and has since aimed to investigate why we see a majority of females at the site, and how they use the area. Sofía got involved in 2017 after completing her bachelor’s degree in marine biology and gaining experience in fieldwork and research (21.19). She explains how she always wanted to come back to the Galápagos Marine Reserve and figure out how she could be a valuable community member through conservation.

One area that Sofía has focussed on, and the subject of her master’s thesis, is the diving behaviour of whale sharks (24.01). Sofía is trying to figure out how deep they go and why they dive. In the study sites, it appears that the sharks are not feeding at the surface (30.00), suggesting they may be feeding at depth. However, they could also be giving birth, which remains to be seen in the wild…

We discuss the theories as to why the GWSP has recorded a majority of females (31.13). Again, this lends weight to the theory that the Galápagos platform may function in their reproductive cycle, perhaps as a nursery ground. This is something Jonathan hopes to answer through their SOSF-funded project, ‘Secrets of the whale sharks of the Galápagos Marine Reserve’. The team hopes to conduct more blood samples and ultrasounds – with the help of an experienced veterinary team – which could give us some more indicators of why females seem to congregate at these sites. Sofía explains the process of carrying out this type of research, which sounds pretty wild; you can’t exactly squeeze a whale shark into a vet surgery, so everything has to be done while free swimming underwater (40.48)!

We then dive into some of our listener questions. First, we answer ‘what do whale sharks eat?’ (45.42) followed by ‘where are they found?’ (47.20). As Jonathan tells us, whale sharks have a global distribution – they are found from the north Mediterranean right down to the south of Australia. Sofía adds that climate change is already shifting their distribution, making it harder to protect them adequately. We also answer, ‘why are whale sharks fished, and is this legal?’ (49.26). Jonathan talks us through the different products that whale sharks may be fished for – including fins and liver oil – but emphasises that this is illegal since they are an endangered species. However, it still happens on the high seas and remains a threat to whale sharks worldwide.

Finally, we find out what fascinating research plans are on the cards for the GWSP. Follow them to find out what goes on this season (52.38).

About our guests

Jonathan Green

Jonathan R. Green is a sciences graduate of the University of North London. He has worked for nearly three decades in the Galápagos Islands and has several thousand dives in the surrounding waters. An early fascination with whale sharks led to the founding of the Galápagos Whale Shark Project with a view to better understanding the part Galápagos plays in their life cycle.

He is an elected Fellow of the Royal Geographical Society of London and, when not in the Galápagos, works on expedition vessels in the Polar Regions. He also teaches photography workshops in destinations worldwide and has won several international awards.

Instagram: @jonathangalapagos

Sofía Green

Sofía Green is a marine biologist from Ecuador. From a young age, her life was intertwined with the Galápagos Islands, which instilled her love for the ocean, adventure, and wildlife. Growing up and noticing the impact humans were having on the planet, she felt driven to work for the conservation of this Earth and to protect its amazing flora and fauna. Last year Sofía graduated with an international master’s degree in Marine Biological Resources (IMBRSea) with a focus on conservation and ecology.

She is currently working on discovering the secrets of ocean giants with the Galápagos Whale Shark Project. Whale sharks serve as ocean ambassadors, and as Sofía states, “by protecting the whale sharks and the ocean areas they use most, we protect many other endangered species under its large fins.”

Besides her work with whale sharks, Sofía is involved in leading volunteer environmental education programs in the Galápagos. She runs coastal clean-ups and activities with the Sustainable Ocean Alliance and Mingas por el Mar (Community work for our Oceans). She also uses wildlife photography to share the beauty of this world through images, alongside impacting stories. “People can only protect what they know and love”.

Instagram: @sofigreenbio

Twitter: @SofiGreen1994