‘I was terrified. The metal of the cage hit the boat with a resounding sound, the waves splashing high. I had just gotten my diving license the week before and I couldn’t actually swim properly. The first shark swam towards the bait. I started to feel warmer and warmer. Was I really going to do this? But when the animal turned out to have little interest in the meat, I became calmer. Once in the cage, my fear turned to fascination. Sharks have been on this earth longer than trees, yet we barely know anything about them.”
PhD candidate Gibbs Kuguru now works at Wageningen University. After a tip from his study advisor, he ended up on a South African boat that lets tourists cage dive with white sharks. That work internship was closer to his childhood dream than the study of medicine in America from which he had recently fled. “On Saturday morning at 7 o’clock, as an eight-year-old, I was not in bed, but I was watching nature documentaries about lions, rhinos and wildebeest trekking. I thought it was strange that people from all over the world came to my country to see things that I hardly ever saw. The major nature parks were a few hours’ drive from our house in Nairobi, but we rarely went there because I have eight brothers and sisters. My dream was over wildlife-biologist, but I did not recognize myself in the people I saw in the documentaries. That’s why it didn’t seem like an option to me.”
After six years on the diving boat, you ended up in biology and did research into the genetic variety of hammerhead sharks in South Africa for a master’s degree in genetics. What came out of that?
“Hammerhead sharks are an endangered species worldwide. They occur in South Africa but we didn’t know much about the local population. My research showed that there was little diversity in the population. With a predator species that produces a few young per year, which take a long time to grow up, you want more diversity. I discussed those results at conferences and a year later the species was given protected status in South Africa. Then I knew: if I want to make a difference, I have to do further research.”
Research itself does not always immediately lead to new policy. Often more is needed.
“That’s right. That is why I think science communication is important and I know all fisheries policy makers in the countries where I conduct research and I give workshops and talks for local fishermen. In a few years there may be no more sharks. It is not enough to publish a scientific paper. You have to be more creative.”
Another way Kuguru disseminates his research is through documentaries. This is what he suggested with other biologists National Geographic a documentary about color change in white sharks. To do this, they made clever use of the behavior of the predators, who jump out of the water during an attack on a seal and can thus be completely seen. The animals only do that in South Africa. It is not known why. The researchers lured the sharks with a fake seal. For the seal they had mounted a color board with shades of gray on a floating scaffold. The moment the shark jumped out of the water, it was photographed from the boat. This allowed the scientists to properly compare the shark’s color with the grayscale board.
Shark fanatics like me love solving such mysteries
You state in the documentary that it appears that sharks become paler when attacked. How can a shark change color?
“We think it is driven by adrenaline released during an attack. We did tests in the lab on white shark skin tissue that we exposed to adrenaline. This caused the pigment cells, the melanocytes, to contract and become lighter. Under the influence of melanocyte-stimulating hormone, the cells produced more pigment and became darker.”
And because it becomes lighter, it is less noticeable?
“That is our hypothesis. It could explain why white sharks always seem to come out of nowhere. That paler color gives an advantage between 10 and 15 meters depth where they hunt. There is still sunlight there, but a lot less. Everything there is paler in color.
“Unfortunately we were only able to photograph a few sharks. I would like to continue my studies, but I first have to find new funding. That is difficult. Shark fanatics like me love solving such mysteries, but it does not directly have applications for humans. While it might make people look at these animals more positively.”
For his PhD research, Kuguru is also looking at skin discolourations in blacktip reef sharks in the Maldives. They increasingly have white spots.
People often don’t even know they are eating shark or ray because it is disguised on the menu
Is it a genetic defect that occurs more often due to inbreeding?
“That is our hypothesis. There is inbreeding due to extreme overfishing. The coloration, known as leucism, occurs in more animal species. People know it as vitiligo. Leucism may be associated with other abnormalities such as infertility and deafness. We don’t yet know what the consequences will be for sharks, but I’m not sure. And suppose you do this with, for example gene drives [een toepassing van genetische modificatie om snel en efficiënt een genetische eigenschap door een populatie te verspreiden] If you can solve it, it will always be temporary because you do nothing about the underlying problem: human consumption.”
In your presentations you show graphs from the WWF report The Shark and Ray Meat Network from 2021. What is striking is that Spain dominates the world trade in shark meat as an exporter, both in terms of value and volume. Italy is the largest importer in terms of value.
“Shocking, isn’t it? Everyone always looks to China when it comes to the shark meat trade, but Europe is responsible for 22 percent of the trade. People often don’t even know that they are eating shark or ray because it is disguised as something on the menu, for example Kalbsfisch in Germany, caldeirada de pata roxa in Portugal or as rock salmon in England. It’s time we look at ourselves instead of pointing the finger east.”
Do you see yourself more as a researcher or a conservationist?
“Deep in my heart I am a researcher, always have been. Someone who likes to discover new things and talk about them. But if we are not careful, soon there will be no more sharks to tell good stories about, and that inevitably makes me a conservationist as well.”
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