Shark Surprise Seeing all this action in the ocean is amazing. Yet to really understand the reef ecosystem, my team and I need to do more. We can’t just watch the fish. We need to count and measure all of them. It’s a big job. By the end of the Pitcairn expedition, we
know the size of this reef community. We’ve measured 14,500 algae and 6,300 coral colonies. We’ve found 5,000 sea urchins. We’ve counted 40,210 fish. T at includes a large population of sharks. T at’s a surprise. Many reefs have few or no
sharks. Instead, they have lots of algae, small fish, and little predators living in them. T ey also have dying corals and other problems. Reefs like that are in trouble. T is comparison tells me something really
important. I’ve found what is missing in an unhealthy reef. It’s sharks. T at’s great, but it’s also a problem. Every
year, people kill up to 100 million sharks. As a result, many shark species are endangered. T ey’re at risk of vanishing from our oceans.
Domino Effect Take away the sharks and bad things happen. At first, a reef looks pretty. It’s filled with lots of colorful little fish. It’s doomed, though. Sharks are top predators. T ey eat lots of
other kinds of fish, yet nothing in the reef eats them. T ey keep populations of other reef organisms from growing too big. Without sharks, the bigger fish that sharks
eat multiply. T ese fish gobble up the smaller fish that eat algae. So the algae grow and grow. T ey smother the coral polyps. T e polyps die. T e habitat crumbles. Finally, what’s leſt is an ocean ghost town.
T e seafloor is bare. T e water is murky. It’s hard to find much life.
8 NATIONAL GEOGRAPHIC EXTREME EXPLORER
Finding Hope I’ve explored dying reefs and ocean ghost towns. T ere are too many of them. Yet this isn’t a story of doom and gloom. Even in the unhealthiest spots, I see hope when I dive. A place off the coast of Africa is a good
example. Here, the water looks like chocolate, and the muddy bottom is bare. I didn’t expect to find much. Boy, was I surprised. One day, my team found an empty shell
on the seafloor. We brought it onto our boat. Suddenly, thousands of tiny baby octopuses squirted out of it. Inside the shell, octopus eggs were hatching. T en, diving around
nearby oil rigs, I got another surprise. I saw beautiful corals growing on the metal supports. I saw red snappers, toothy barracudas, and other fish, too. Fishing boats can’t get close to the rigs.
T ey can’t catch the fish. So the fish are safe. Finally, one day we saw silky sharks. I couldn’t stop smiling. T ere’s hope here.
Lessons Learned In Africa, I learned that you can find life where you least expect it. Also, fish like places where people can’t fish. If we protect places from fishing, the fish,
including sharks, will come back. It takes time, yet that’s the first step to rebuilding healthy reef ecosystems. In Pitcairn, I saw the goal. T is is what a
reef should look like. My bigger goal is to save life in our seas. Now I know how to tell if I’m succeeding. I’ll see sharks.
Dive into Enric Sala’s other ocean missions and learn about National Geographic’s campaign to save our seas at
www.pristineseas.org.
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