Photography by Dr. Simon Pierce
Innovative techniques used on whale sharks in the Galapagos to find out more about their reproduction
Researchers in the Galapagos have successfully completed ultrasounds on free-swimming whale sharks, and taken blood samples from adult whale sharks for the first time ever in the wild. The incredible results allowed them to see and identify reproductive organs, such as the ovaries, and even developing follicles. These technologies hold promise for finally unlocking the mystery of breeding in the world’s largest sharks.
A team of global whale shark experts, comprised of scientists and conservationists from the Galapagos Whale Shark Project (Ecuador), Galapagos National Park (Ecuador), Okinawa Churashima Foundation (Japan), University of San Francisco/Galapagos Science Center (Ecuador) and the Marine Megafauna Foundation (USA), has just returned from a two-week expedition to Darwin Island, in the far north of the Galapagos Archipelago.
This remote volcanic island is one of the few places where huge adult female whale sharks, up to 14 m (45 ft) in length, are commonly seen each year. The main aim of the expedition was to assess the sharks’ reproductive state.
Jonathan R. Green, the expedition leader and founder of the Galapagos Whale Shark Project, notes: “Almost nothing is known about the reproduction of these giant sharks. After I first saw these huge female whale sharks in the far north Galapagos, I realised that this was a great opportunity to learn more. We’ve been able to put together an experienced team to research sharks in this remote area, one of the world’s most isolated dive sites.”
Dr Simon Pierce, an expedition member from the Marine Megafauna Foundation, explains further: “Whale shark breeding is a mystery. Only one pregnant shark has been physically examined so far, back in 1995 in Taiwan. That ‘megamamma’ shark had 304 little whale shark eggs and pups inside, all less than 60 cm in length.”
The team conducted scans using a 17 kg ultrasound system in a waterproofed case. Whale sharks have tough protective skin, more than 20 cm thick on some individuals, so the 30 cm penetration of the ultrasound waves proved a challenge – not to mention the difficulty of carefully checking the whole belly area of a gigantic shark while it is swimming. Dr Matsumoto had to use a propellor system mounted on his air-tank to keep up with the sharks.
“We use some interesting technology anyway, but working with the Okinawa team was something else”, commented Dr Pierce. “I felt cool by association. We saw dive groups a couple of times at the site, and I can only imagine what they thought – why is that guy diving with a briefcase? And a jetpack?”
Dr Matsumoto reports that the initial results were promising: “We confirmed the presence of follicles in the ovaries but none of the images captured embryos or egg capsules inside the uterus. These adult female sharks we saw at Darwin Island might be on their way to mate further offshore. I am confident that we can judge the sexual maturity, and probably also determine the pregnancy of whale sharks in the field, using the underwater ultrasound”.
The researchers attached satellite-linked tags to the sharks to track their onwards movements. Professor Alex Hearn from the University of San Francisco/Galapagos Science Center explains: “We’ve tagged whale sharks in Galapagos before, but there are lots of predatory sharks at Darwin and they often try to eat the tags, which can rip them out of the whale sharks almost immediately. To reduce early tag loss, we tried a different method on this trip, clamping the tags to the tip of the dorsal fins. All tags are transmitting well, so we should get great information on where these sharks swim over the months to come.”
Project member Dr Alistair Dove, from Georgia Aquarium, notes that these tags could document some amazing behaviours: “Whale sharks are already known to be the deepest-diving of all fish. The current depth record is 1,928 m – well over a mile – set by a juvenile whale shark. Larger, older animals can generally dive deeper than young smaller ones, so perhaps we will challenge that record.”
Kiyomi Murakumo, from Okinawa Churashima Foundation, successfully collected blood samples from six adult sharks – no easy job. Her colleague, Dr Ryo Nozu, analyzed the results immediately following the trip: “Sex steroid hormone levels in the blood are an excellent way to monitor reproduction in individual sharks. This study measured levels of estradiol, progesterone and testosterone of wild, adult female whale sharks for the first time in the world. Estradiol could be associated with follicular development, and progesterone could be involved in ovulation and pregnancy. Over time, as we sample more whale sharks, we can build up a complete picture of their reproductive cycle by combining the blood sampling with the ultrasonography.”
Jonathan R. Green added: “These big female sharks are not going to give up their secrets easily. One thing is clear: there’s a lot of work still to do to understand the reproductive processes of this endangered species. However, this trip proved that it is possible to research their breeding in the wild. We’ll continue to hone our techniques and build upon this knowledge, as we need to understand these enigmatic sharks and protect them through their life cycle.”
This project was supported by Galapagos Conservation Trust, Planeterra Foundation and Temperatio.
About the Galapagos Whale Shark Project: The GWSP is comprised of a small group of scientists and volunteers whose common interests are the marine environment, diving and conservation. The Galapagos Whale Shark Project, combining the efforts of all our partners through a multi-disciplinary study, gathers the data necessary to better understand whale sharks. Through this understanding we hope to create awareness and the foundations necessary for their protection and conservation.
About Okinawa Churashima Foundation: The Okinawa Churashima Foundation (OCF) is the administrative arm of the Ocean Expo state-run park established to commemorate the Okinawa International Ocean Exposition that was held in Okinawa in 1975. OCF has been managing and maintaining the Okinawa Churaumi Aquarium (OCA), the Okinawa Churashima Research Center (OCRC) and the Ocean Expo Park. OCA presents the rich nature of Okinawa’s marine environment and strives to create a place where people can encounter the abundant variety of sea life found in the Kuroshio Sea surrounding these southern isles. OCRC promotes advanced research, industrial development, and improvement of park functions for further contributions to society. For more information about OCA visit https://churaumi.okinawa/en/ About OCRC visit http://churashima.okinawa/en/
About Marine Megafauna Foundation: MMF’s vision is a world in which marine life and humans thrive together and we aspire to attain it by saving threatened marine life. Our target group is marine megafauna, which is vital to the delicate balance of the marine ecosystem. When we protect ocean giants, we also achieve an umbrella protection for a wide variety of marine species. Consequently, we target coastal communities that represent the biggest threat to these species and, as a result, to their own food security. Through our 4 pillars, we provide an integrated solution: by using our research findings to educate and inspire the masses, we gather the necessary tools to provide sustainable marine conservation strategies for communities and policymakers to bring about lasting positive change. Finally, by empowering, informing and giving a voice to local communities, we help to create a generation of Ocean Ambassadors and Guardians, who cherish and understand the marine ecosystem. For further details, please see https://
About Georgia Aquarium: Georgia Aquarium is a leading 501(c)(3) non-profit organization located in Atlanta, Ga. that is Humane Certified by American Humane and accredited by the Alliance of Marine Mammal Parks and Aquariums and the Association of Zoos and Aquariums. Georgia Aquarium is committed to working on behalf of all marine life through education, preservation, exceptional animal care, and research across the globe. Georgia Aquarium continues its mission each day to inspire, educate, and entertain its millions of guests about the aquatic biodiversity throughout the world through its hundreds of exhibits and tens of thousands of animals across its seven major galleries. For more information, visit georgiaaquarium.org
About Galapagos Science Center: Universidad San Francisco de Quito USFQ is a liberal arts, non-profit, private university located in Quito, Ecuador. It was the first totally private self-financed university in Ecuador and the first liberal-arts institution in the Andean region. Academically, USFQ ranks as one of the three-top universities (category A) in the ranking of Ecuadorian universities. USFQ is the only university in the world with a campus in the Galapagos Islands, and in the Yasuni Biosphere Reserve(Tiputini Biodiversity Station), one of Earth’s most biodiverse areas. The Galapagos Science Center (GSC) is a joint effort between USFQ and the University of North Carolina at Chapel Hill (UNC). This facility was constructed on San Cristobal in the Galapagos Islands, with the aim of advancing a shared goal of promoting science and education that will help protect these fragile island ecosystems and enhance the lives of their inhabitants. For more information, visit http://galapagosscience.org.
About The Galapagos Conservation Trust: Galapagos Conservation Trust (GCT) is the only UK charity focussed solely on the conservation of one of the most unique and ecologically important, but vulnerable, areas in the world, the Galapagos Islands. With over 20 years of experience, we partner with Ecuadorian authorities, NGOs, local communities and leading researchers to support impactful Science & Conservation programmes and deliver community outreach across the Archipelago through our Education & Sustainability programme. We have been supporting the Galapagos Whale Shark Project since 2011. galapagosconservation.org.uk
About Planeterra’s Ocean Health Fund: In partnership with G Adventures, and supported by thousands of travellers from around the world who’ve sailed on the G Expedition ship, Planeterra has been able to support several organizations that specialize in protecting the health of our oceans. Planeterra has invested over $350,000 into these programs over the last five years through the Ocean Health Fund, with its most recent recipient of funds being the Galapagos Whale Shark Project. Planeterra is proud to support such a ground-breaking initiative, making new, important discoveries every day about the magnificent whale shark. Planeterra.org/oceans
About Planeterra Foundation: Planeterra is a non-profit organization, established in 2003 by G Adventures with a mission to connect partners and local communities to the benefits of tourism by developing and supporting community-owned enterprises while promoting more responsible travel. Planeterra connects social enterprises to the tourism marketplace by providing catalyst funding, capacity training, and a market link for small businesses supporting women, youth, Indigenous communities and organizations working for environmental conservation. For more information visit Planeterra.org
About G Adventures: G Adventures is a responsible adventure travel pioneer and social enterprise offering more than 700 affordable small group tours, safaris and expeditions to more than 100 countries on all continents. Powered by a global team of passionate travellers, the award-winning trips embrace local accommodation, cuisine and transport to put travellers on a first-name basis with the planet’s people, cultures, landscapes and wildlife. Their intimate and responsible approach to small group travel introduces travellers to the highlights of a destination while offering the freedom and flexibility to explore it on their own. Whatever age, interest, ability or budget, G Adventures has a true life-changing experience for everyone. For more information please visit www.gadventures.com