For the Love of Sharks: Our 100th Episode!

SHOW NOTES

This episode is an extra special one – it’s our 100^th! To celebrate this milestone, our host Dr Isla Hodgson looks back across 100+ hours of conversations about sharks with scientists and conservationists from around the world and attempts to distil them into five key lessons she’s learnt from the last five years. And in between, we hear some special messages from previous guests!

1. We really don’t know that much about sharks.

If there’s anything I’ve learnt in the last five years of doing this podcast, it’s that we have only just scratched the surface in terms of our understanding about sharks and their relatives. For the vast majority of species, we still don’t know key aspects of their biology and behaviour – like where and how they mate, where they give birth, even where they spend large amounts of time (basking sharks, looking at you). This is even true of the more charismatic, well-known and better studied species. Take perhaps the most famous species of all: the great white shark. As we’ve found out from white shark experts like Ali Towner and Alison Kock, who have studied these animals their whole lives, there are still great mysteries around how they live their lives. Mating has never been scientifically recorded in detail and we still don’t really know where they give birth – although we have some clues. This is also true of the largest fish in the ocean, and many people’s favourite, the whale shark. From speaking to Jonathan and Sofia Green of the Galapagos whale shark project, we learned that again, little is known about their pupping and nursery grounds. Dr Sammy Andrejaczek, expert in shark vertical movements, revealed that whale sharks are one of the deepest diving species, wracking up depths of over 1000m; but why they do this remains a mystery. And Amani-Webber Schultz taught us, in our third-ever episode, that whale sharks have teeth (or more accurately, dermal denticles) on their eyeballs and we don’t know why.

The most well-studied species are those that hang out in shallow, coastal environments – like lemon sharks, reef sharks and nurse sharks. For those, we do have information on their reproductive habits – as we found out from marine biologist and founder of Sharks4Kids, Jillian Morris-Brake, baby lemon sharks are born in sheltered, mangrove nurseries where they grow up among the tangled roots. But other crucial information, like their population sizes and exact lifespans, is unknown. Even the laid-back Pacific nurse shark – a beloved species to PhD researcher Sergio Madrigal Mora – is classed by the IUCN as Endangered mainly because we know so little about their populations. 

But if that is for the more well-known and easier-to-study species…what about our friends in the deep sea? This is one of our favourite topics on the podcast, and we’ve discussed this in depth (excuse the pun) with many fabulous experts, including Dr Brit Finucci, Dr Paul Clerkin and Sofia Graça Aranha. For the vast majority of deep-sea species, we are still learning the basics, even down to their taxonomy. In this realm, we are still discovering species that are new to science, and the surprising and fantastical adaptations that help them survive in such a difficult environment. As we learned from Professor Jerôme Mallefet, an astonishing 11% of sharks are bioluminescent, meaning they can produce their own light; and that’s just the ones we know about.

So, there is much still yet to learn about the World of Sharks. But that doesn’t mean that we haven’t made some spectacular discoveries over the years.

2. From what we know…sharks are incredibly diverse, and perfectly adapted to survive and thrive in almost every ecological niche under the sea.

If you can think of any lifestyle, any diet, any habitat in the ocean…there’s a shark for that. We have massive filter-feeding sharks that feed only on plankton, like the basking sharks we met while in the field with Alex McInturf in Ireland. We have tiny, glow-in-the-dark sharks that fit in the palm of your hand and exist over 600m below the surface. We have sharks that are ambush predators, who camouflage themselves so effectively against the seafloor that even the people who study them – like Jake Davies and Eva Meyers of the Angel Shark Project – find it hard to spot them. We even have a shark that likes a bit of salad every now and then: the bonnethead shark, which we learned has a diet of up to 90% seagrass (thank you to shark digestive system expert Dr Leigh for bestowing us with that fact!).

In fact, there are over 538 known shark species (and counting), which come in all shapes and sizes. And then we have their close relatives, the rays and skates, of whom there are approximately 630 described species. So it’s safe to say that the ocean is shark-infested, but in the best possible way – they fill almost every ecological niche, from the slow-living sleeper sharks in freezing polar waters, to the sun-loving reef sharks of the tropics and, at the other extreme, the epaulette shark, who hangs out in tidal pools and pretty much exists in a hot bath.

And a lot of what we’ve explored on this podcast is why and how sharks have been so successful. From palaeontologists like Professor John Long, Dr Jack Cooper and Dr Emma Bernard we’ve learned that the shark body plan has been crafted over 440 million years of evolution. Like finely-tuned machines that have been tinkered with over and over again, their biological engineering is optimised for survival. From Dr Erin Dillon we learned about their incredible skin, which is like no other in the animal kingdom and offers such a serious hydrodynamic advantage that competitive swimmers have been banned from wearing costumes that emulate it. Max Baum spoke to us about their incredible and highly specialised teeth, which have carried sharks through five mass extinctions by allowing them to utilise a variety of prey sources. Dr Lauren-Eve Simonitis, Dr Lucille Chapuis, Dr Lily Fogg, and Professor Stephen Kaijura have all talked about their super-powered senses, from a highly tuned sense of smell (in some species) to a well-developed inner ear and a special sixth sense, that allows them to detect electrical signals from the surrounding environment (which, amazingly, helps them navigate the oceans). And with Dr Kara Yopak, director of the aptly named ZoMBIE Lab, we learned about the brains behind these operations and discussed how sharks are more intelligent than we might first think. Which brings me onto my next lesson…

3. Sharks are NOT the ‘mindless killers’ that Hollywood would like you to believe.

In fact, they are highly intelligent and capable of complex behaviours – including social behaviours. Many studies have shown that some sharks are capable of learning from their peers and even recognising other individuals, like lemon sharks. Dr Bryan Keller’s research told us that juvenile lemon sharks choose to swim with others that were familiar to them; in other words, they preferred to hang out with their ‘friends’. Dr Yannis Papamastiou found similar behaviours in grey reef sharks in French Polynesia, finding that the same individuals moved to the same places together – heading out to forage at night, before returning to their preferred part of the reef to rest together during the day. Yannis believed this is because they were learning from each other where good food was located.  

And of course, there’s the sharks’ clever cousins: the rays. Researchers, like Dr Kyle Newton, have been able to teach stingrays how to solve puzzles, like mazes. And then there’s the most intelligent fish in the sea: the manta ray. These big-brained gentle giants show signs of advanced cognitive abilities, like self-awareness, exceptional memory and complex social structures. We found this out for ourselves when we headed to the Seychelles to assist marine scientists Dillys Pouponeau and Ellie Moulinie, research officers at the Save Our Seas Foundation D’Arros Research Centre (SOSF-DRC), who could recognise individual mantas from not only their unique belly-spot patterns, but also their individual behaviours.

In fact, many of our guests have said that sharks and rays have individual personalities – our own CEO James Lea could identify the study subjects for his PhD, silky sharks, down to the individual because of how they acted around him. And Alison Kock, white shark expert, said her greatest surprise in over two decades of working with this species is how curious they could be.

As for their relationship with humans, sharks are far from bloodthirsty man-killing machines. Yes, shark bite incidents do happen, and they can be devastating. But the truth is, they are rare. As Chris Pepin-Neff an expert in shark bite incidents told us, fatal shark bites happen because of a combination of different biological and ecological factors. More often than not, it’s a case of mistaken identity, or what is known as a ‘test bite’, where the shark is trying to find out what the human is.

But again, these are extremely rare cases. Even with the larger, more predatory species – like great whites, tigers and bulls, who are responsible for the most fatalities – the vast majority ignore human presence altogether. Carlos Gauna, a photographer and drone pilot who specialises in capturing remote footage of white sharks off the coast of California, has shown time and time again that sharks swim alongside humans without us really knowing. Sometimes they show curiosity, but nine times out of ten, we are just not on the menu.

And, there are hundreds of other species who want nothing to do with us at all. Take the shyshark for example – a small shark endemic to South Africa, who curls up into a donut when threatened. They even cover their eyes with their tail!

So, there is so much more to sharks than Jaws might have led you to think. And – we’ve had it confirmed on this very podcast – Megalodon is very much extinct. So Jason Statham, if you’re listening, stand down.

4. There is no ‘one way’ to do shark science.

What I’ve learned from the 100 or so conversations I’ve had with our experts is that I’m not the only person who has zig-zagged through their career like a pin ball. Everyone has had a gloriously wonky path to where they are now; and only a few people went straight into shark science from being a shark-obsessed kid. Some really amazing shark scientists grew up far away from the coast, without any access to the ocean. Others stumbled into sharks from another field or career, bringing with them their own unique skill set and experience. We have project leaders who failed biology in high school, or thought they were only good at the arts – or felt that a career in science wasn’t for them, and worked many other jobs before finally finding that dream project.

The truth is, no-ones trajectory is linear. So if you want to work with sharks, but your path isn’t looking like a straight line: no-ones is, and that’s just fine. In fact, it’s great. Because the best thing about conservation is that we need all hands on deck. Akira Biondo said something recently on the podcast that stuck with me – whatever your passion or skill set is, there’s a space for you in science and conservation. If you’re great at writing stories, we need you. If art is your thing, we need you, because we need people to care. If you’re working in anthropology, or politics, or business and want to work with sharks – we need you. Your skills are so applicable, because a lot of conservation is working with and understanding people.

And, as we learned from Jasmin Graham – co-founder and president of Minorities in Shark Sciences – as long as you are following the scientific method, and have curiosity, you are doing science. You don’t need to be affiliated with a particular institution or have a huge list of papers to your name to start. But an important thing is to find your people; mentors, colleagues and friends who will lift you up and support you in chasing your dreams. I think that’s the best lesson we can learn in our early careers.

5. Sharks are in trouble…but there is a huge amount of hope.

It can be hard not to feel down, or panicked, about the threats facing our oceans. We’ve talked a lot on the podcast about the plight of sharks, rays and chimaeras; over one third are currently threatened with extinction. Given how little we know about them, that figure might even be a little higher. There may even be species that go extinct before we even know about them.

We’ve also talked about the reasons why. Categorically, the greatest threat to sharks and rays is overfishing; sharks in general are long-lived, slow to mature and have small numbers of well-developed young, making them especially vulnerable because they can’t reproduce fast enough to keep up with the rate that we are fishing them. But they also face pressure from climate change, pollution, microplastics, habitat loss and degradation…the list goes on and on.

But something that has given me tremendous hope is this podcast. Every episode, I sit down with incredibly passionate, determined and hard-working people from all walks of life who have come together over one goal: the love of sharks, and the drive to safeguard them. These people come from all corners of the world – from Greenland to Spain, Seychelles to South Africa, the Oregon coast to Argentina and Indonesia to the very bottom of New Zealand; even Papua New Guinea. And there are people tackling this problem from all angles. Researchers are working to fill those gaps in our knowledge so we can better inform management and conservation strategies. NGOs and policymakers are fighting on a world stage to secure better protective legislation. Project leaders working on the ground, with their communities, fisheries, and local businesses, to find solutions that work for both nature and people. Storytellers and creatives lending their talents to communicating science and changing public perceptions of sharks. Pioneers challenging stereotypes and reaching a hand out to others, to help champion other scientists and conservationists who deserve to have a seat at the table but face significant barriers to get there.

Every time, when I feel frustrated or down about the state of the world, I look back on all these inspiring conversations I’ve had with these incredible people, chipping away on their unique part of the puzzle – and I don’t feel so alone.

And I hope you, our lovely listeners, draw hope from this too, and recognise that you also have a role to play in changing the fate of sharks, whatever your background. Because after all, I’m assuming you’re here for the same reason that I am – all for the love of sharks.

Thank you for listening and supporting us over the last 100 episodes! Here’s to the next 100…