Exploring Galápagos, the sharkiest place on Earth
SHOW NOTES
We start as always with Pelayo’s most memorable experience [7.00]. This is a very hard question for someone who spends their days exploring a Zoologist’s paradise! Pelayo recognises the privilege to dive in some of the “most remote and special parts of our blue planet”. However, one experience that stands out is his first ever dive on Darwin island, the northernmost island of the Galapagos. On a ‘normal’ day here you can surrounded by hundreds of scalloped hammerhead sharks, gigantic whale sharks, tuna and other fishes; picture yourself just sitting amongst such an astounding diversity of life! Pelayo has laughed at the sheer spectacle of it. This particular dive site is called ‘the theatre’ because it is a platform of rock at different levels where divers are ‘parked’, and all they have to do is look up at this incredible natural spectacle all around them.
So how did Pelayo come to the Galapagos in the first place [10.08]? He was born in northern Spain, known for its mountains but also for its proximity to the ocean. His parents came from southern spain, and Pelayo remembers a childhood spent in or by the sea. His first photo in a snorkel mask was taken at age 2! Pelayo was always fascinated by the ocean, which drove him to choose science at school. At 14 or 15 he decided that he wanted to be a marine biologist. But Pelayo also found school difficult, saying that he was “too hyperactive” to sit still and concentrate, and as a result thought the academic system wasn’t for him. Through talks with his mother, they decided that the British education system – with it’s shorter degree length and focus on practical application of science – was better for him. Pelayo attended the University of Aberystwyth in Wales, UK, to study marine and freshwater biology. Luckily, Pelayo really enjoyed it – especially the practical aspect (lots of field trips and labs). He loved it so much that he pursued a masters, and later a PhD. The Galapagos came along after Pelayo’s studies. Since childhood, Pelayo had wanted to work in the Galapagos, and he had been emailing his current employer – the Charles Darwin Foundation – since his undergraduate! This persistence paid off. Around the time Pelayo completed his PhD, a job opening came up at the foundation and Pelayo was the perfect candidate. He got his happy ending.
So, what is the Galapagos actually like [14.05]? Pelayo describes it as “the real Jurassic park or Disneyland of the natural world”. A collection of dramatic Volcanic islands rising up out of the sea, 1,000km away from the nearest coast, the Galapagos is very isolated, remote and wild. Only a handful of animal groups managed to get there and thrive – including marine iguanas and giant tortoises. These prehistoric reptiles against the black, volcanic setting is what comes to mind when people think about the Galapagos, alongside Darwin’s iconic voyage aboard the HMS Beagle. But in Pelayo’s opinion, the most amazing part of the Galapagos is beneath the waves. Here is the meeting of three large ocean currents: the Humboldt Current, the Panama Flow and the Cromwell Current. The Humboldt and Cromwell bring cold, nutrient rich water from the depths, where it meets warmer, more tropical waters from the north. This unique mixture of warm and cold supports a rich, complex marine food web – one which contains a bizarre mix of animals including fur seals and penguins, but also true coral reef systems with tropical fishes and whale sharks. Picture yourself basking in the tropical sun next to the penguin, before diving in a cold-water kelp forest! It’s like lots and lots of different places from around the world, all mashed into one incredible place – that’s the Galapagos.
Part of this incredible diversity is a number of shark species [21.00]. In fact, Pelayo and his team released a study in 2016 that identified the northern islands of Darwin and Wolf as having the largest reef fish biomass ever recorded, which largely consisted of sharks! Eight years later these islands retain their title as one of the sharkiest places on earth. This is largely down to the efforts of the Ecuadorian government, who established the Galapagos Marine Reserve (GMR) in 1998. As a result, the islands have been protected from industrial fishing. There are still threats from human activity – as we’ll talk about a little later on – but Darwin and Wolf still remain one of the best places in the world to dive with sharks. One of the most iconic images of the Galapagos (which you can see in the image used for this episode!) is that of the schooling scalloped hammerheads, who can be seen in their hundreds [26.00]. They will also visit one of the many cleaning stations, where much smaller fishes will nibble and ‘peck’ at their skin, taking off any pesky parasites. The hammerheads will go into a sort of trance-like, relaxed state. It’s like a spa for sharks! Darwin island is also known for its seasonal aggregations of whale sharks, the world’s largest shark species. These are typically fully grown females, over 12 metres long, just cruising on by among the bustling traffic of hundreds of hammerheads.
And that’s just the water above the reef. On the reef itself is the Galapagos shark, which Pelayo describes as the “owner of the reef” [26.59]. They can be very territorial, and have no problem letting you know who is boss, sometimes coming right up to the mask of a diver! “They get very close to your personal space, to let you know that you are in their turf and not the other way round.” Says Pelayo. But there is no reason to worry. Just blow some bubbles through your regulator and they’ll soon retreat. Or, as Pelayo has practised, shout ‘go away!’ down your rebreather! On the reef you may also find white- and black-tipped reef sharks, and silky sharks.
Outside of the reef are yet more shark species. In deeper water, you may find Odontaspis pherox, the small-tooth sandtiger shark or “the monster of Malpelo” [28.15]. And moving out into the open ocean, you might encounter a host of pelagic species like blue sharks, thresher sharks, and mako sharks.
Pelayo and his team have monitored these shark populations for many years [35.00]. His research is very varied – from finding out the basics, like what species are actually there, how many, and the numbers of males and females, to much more complicated questions, like why they are in the Galapagos and what they are eating. Pelayo describes it like a murder mystery, trying to follow all the clues to make up a whole story. And to solve the mystery, he needs a range of methods and techniques. These include Baited Remote Underwater Video stations (BRUVs) – underwater cameras that have a tiny piece of fish attached that the shark can smell but not eat. You can then watch back the video footage, and see who came to visit! Pelayo has also collected genetic data and stabilised isotopes, which can be used to give you information on where a shark has come from, who it is related to, and what it has been eating along the way.
One particularly interesting finding across the years concerns a very unusual nursery site [42.11]. A few years ago, Pelayo and his team at the Charles Darwin Foundation were given the chance to work on the E/V Nautilus, an oceanographic vessel that has a Remote-Operated Vehicle (ROV) capable of going 4, 000 metres deep. They wanted to explore the hydrothermal vents just north of Darwin. Hydrothermal vents are cracks in the earth’s crust, located on the seabed. Water that percolates through this crack is superheated by the magma beneath, and can reach astonishing temperatures of 400 degrees Celsius. The interaction of seawater and hot magma results in the release of chemicals, the deposits of which form huge, towering structures, sometimes known as ‘chimneys’. All in all, they are hugely inhospitable environments and it’s hard to believe any life could survive there. But scientists have discovered whole communities dependent on these very unique conditions. And during their research expedition, Pelayo and everyone on board the E/V Nautilus discovered something mind-blowing: rows and rows of egg-cases, that looked like that of a shark or ray! Using the ROV, some of the egg-cases were extracted and brought up to the surface, where genetic samples were sent to Professor Mahmood Shivji of the Save Our Seas Foundation Shark Research Center. Mahmood was able to identify the egg-cases as that of a deep-water skate species, who they suspected were using the hydrothermal vents as some sort of natural incubator – albeit an extreme one! How amazing is that?
All of the data that Pelayo and his team are able to collect is crucial to protecting the sharks, rays and skates of the Galapagos [50.11]. Although the Galapagos itself is protected by the GMR, many of the species that visit it – including the whale sharks and scalloped hammerheads – are migratory. This means that they are threatened by activity outside of the protected area, including high levels of Illegal, Unregulated and Unreported (IUU) fishing. Pelayo is working closely with the Ecuadorian government to help protect sharks across borders and jurisdictions. One project he is working on at the moment is Habla Tiburón, which roughly translates to ‘WhatsApp shark’ in English. The idea is to work with fishing communities and other stakeholders, to find ways of fishing more sustainably to both protect sharks and coastal livelihoods. This involves a mixture of actions, from creating market incentives to collecting local knowledge to inform policy-making. As Pelayo says: “The idea is that we move beyond protected areas, and start working with the fisheries. And that is the biggest challenge for sharks and rays, the biggest challenge. But we have to be positive right? We have to grab the little hope and keep pushing it.”
The papers we mentioned in this episode are:
Salinas-de-León, P., Acuña-Marrero, D., Rastoin, E., Friedlander, A.M., Donovan, M.K. and Sala, E., 2016. Largest global shark biomass found in the northern Galápagos Islands of Darwin and Wolf. PeerJ, 4, p.e1911. Read here
Salinas-de-León, P., Phillips, B., Ebert, D., Shivji, M., Cerutti-Pereyra, F., Ruck, C., Fisher, C.R. and Marsh, L., 2018. Deep-sea hydrothermal vents as natural egg-case incubators at the Galapagos Rift. Scientific reports, 8(1), p.1788. Read here
ABOUT OUR GUEST
Pelayo Salinas de León
Co-Principal Investigator, Shark Ecology and Conservation, Charles Darwin Foundation
Pelayo is a biologist, explorer, and underwater photographer committed to ocean protection and shark conservation. He has been a senior marine ecologist with CDF since 2012, and from 2016 to 2021 he was part of National Geographic Pristine Seas, contributing to its mission of helping to protect our ocean’s last wild places. He is currently combining his role as Principal Investigator of CDF’s shark ecology project with his work with several international foundations.
Pelayo earned a Master’s degree in environmental management in 2007 and a Doctorate in marine biology in 2010 from Victoria University of Wellington, New Zealand. Before fulfilling his dream of working in the Galapagos, he worked in Indonesia, New Zealand, and Cuba.
Author of over 70 scientific publications, Pelayo explores the biodiversity and beauty of some of the most remote places on the planet during his international expeditions, contributing to their protection. Some of his recent expeditions include the Ogasawara Islands and the Marshall Islands.
Pelayo is a passionate advocate for ocean conservation and science communicator. His scientific work has been featured in documentaries and articles in international magazines, including ‘NatGeo Wild Galápagos’, ‘BBC Galápagos’, or ‘The Shark Side of the Moon’.
You can follow Pelayo on Instagram (@pelayosalinas) and X/Twitter (@PelayoSalinas).
You can find out more about the Charles Darwin Foundation here
