Radio tagging captures behaviour of largest fish on earth

The Cendrawasih Bay National Park Authority along with experts from Conservation International, WWF-Indonesia, Hubbs Sea World Research Institute (HSWRI) and the State University of Papua recently completed the first expedition to tag whale sharks with radiofrequency identification (RFID) tags.

Because the whale sharks were tagged, the team was able to capture the sharks literally sucking fish out of fishers’ nets at Cendrawasih Bay on video. The 180,000 km² marine area is where Conservation International along with The Nature Conservancy and World Wildlife Fund work with government authorities, private organisations and local people to conserve the diversity and abundance of marine life.

Widely used in the US for tracking pets, these tiny pill-sized transmitters are injected beneath the skin and serve as a unique, permanent ‘ID card’ which can be scanned with a receiver wand. It will allow scientists to determine a shark’s history whenever it is next encountered.

“This technology has never been tried before with whale sharks, in large part because it’s fairly impractical to swim after the giants with a receiver wand underwater,” said Dr Mark Erdmann, a marine biologist who was on the expedition and is the senior advisor to CI-Indonesia’s Marine Program.

“What makes this tagging possible in Cenderwasih Bay is the unique habit this population has of aggregating at bagan fishing platforms to feast upon the small silverside baitfish that the fishers are catching.”

Led by Dr Brent Stewart, senior research scientist with HSWRI, the expedition team tagged 30 individuals over five days, 29 of which were adolescent males between 3-8 m. The team is attempting to rapidly determine the size of this recently discovered whale shark population in the bay and monitor individuals’ movements in the area over the coming years.