Expedition to Palmyra Atoll, Day 9: Shark!

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(Editor’s note: Alison Green, senior marine biologist at The Nature Conservancy, is spending the next two weeks diving and exploring Palmyra Atoll as part of the first marine assessment of the atoll. Follow her posts from Palmyra on Cool Green Science…and learn more about the expedition.)

Shark: Just the word seems to strike fear in the heart of most people, and for good reason — sharks kill and maim people every year.

However, while some species are dangerous, many are mild-mannered and pose no threat to humans. This is particularly true on coral reefs where most sharks are small (less than six feet long).

Sharks are slow growing, long-lived and slow to reproduce, so they are particularly vulnerable to overfishing. Consequently, they are becoming increasing rare on most of the reefs of the world.

That is one of the reasons that Palmyra is so special. Sharks are protected here, and there are a lot of them. We see them everywhere we go — mostly black and white tipped reef sharks, but also lots of grey reef sharks. These sharks are generally small (less than six feet long), but some are eight feet long.

Yesterday we went to a dive site called “Hammerheads” to see a completely different kettle of fish – hammerhead sharks. They grow up to 14 ft long, and are considered dangerous to humans.

When we entered the water, we were quickly surrounded by grey reef sharks, which raced up to us and spent the next hour swirling around us. It was hard to work out exactly how many there were, but I could see at least 12 (each six to eight feet long) at any one time so there must have been a lot more. Grey reef sharks are very inquisitive, and often swim right up to you, which can be a bit disconcerting if you’re not used to it. Sometimes they can be aggressive, but mostly they are just curious — cruising past, around, over and under you.

Then suddenly there it was — a hammerhead shark. It was huge, probably 12 ft long and twice the size of the other sharks. Wow, what a sight! They are magnificent creatures, slightly menacing, but wonderful to see and mesmerizing to watch. What a privilege and a rare treat it is to see them these days.

(Image: Black-tip reef shark, Palmyra. Credit: Kydd Pollock/TNC.

Video 1: Two black-tip reef sharks – make sure you wait for the second one! Credit: Kydd Pollock/TNC.

Video 2: Hammerhead shark, Palmyra. Credit: Kydd Pollock/TNC.)

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