Understanding The Ocean's Biggest Fish

How one research team is using ultrasound and blood sampling techniques pioneered in Japan to study whale sharks in the wild off the Galápagos

- Don Silcock

Nature’s Creche

That these huge animals have travelled incredible distances while pregnant to gather at such an iconic location seems like a perfect script for a TV documentary! It certainly sends a strong emotional appeal to those of us who love the ocean: a special place, far from land, where female whale sharks can give birth and nurture their young safely – Nature’s creche for the ocean’s behemoths.

Scientists don’t work on emotions though; they need facts. But how do you gather facts on large wild animals that are underwater in a remote location swept by strong currents and where contact is fleeting at best? The short answer: with great difficulty. But a team of marine scientists led by Rui Matsumoto set out to do exactly that.

Okinawa Churaumi Aquarium

Churaumi (meaning “beautiful ocean”) in Okinawa, Japan is one of the largest aquariums in the world. It is renowned for its 7,500-cubic-metre main tank called “The Kuroshio Sea”, with its captive whale sharks, manta rays and several species of large sharks, together with its successful in-house breeding programmes for mantas and bottlenose dolphins.

Despite the huge size of the facility, hosting large pelagic creatures in a confined environment remains a controversial topic, but peel that onion a bit and it becomes clear that a great deal of work goes into monitoring the health of those animals. Interestingly, the techniques developed to do that monitoring are playing a major role in understanding the health and condition of these animals in the wild.