WRITTEN BY MARK ERDMANN ON conservation.org
November 16, 2011
Looking out over a calm sea towards Indonesia’s mist-shrouded Arfak Mountains, expectations are high for our imminent departure to Cenderawasih Bay National Park to seek out the world’s largest fish, the whale shark (Rhincodon typus). We’re at anchor in the beautiful bay of Manokwari, the capital city of West Papua in the Bird’s Head Seascape. Soon the rest of our team — including my co-expedition leader Dr. Rod Mast from CI and world-renowned whale shark researcher Dr. Brent Stewart from Hubbs SeaWorld Research Institute (HSWRI) in San Diego — will arrive and we’ll begin our journey.
Our team brings together scientists from CI, HSWRI, and our partner organizations WWF-Indonesia and the Cenderawasih Bay National Park Authority. During the coming week we’ll do a quick survey of the reefs of Cenderawasih Bay, which comprise Indonesia’s largest marine national park. CI consultant, scientist and ichthyologist Dr. Gerald Allen has proclaimed this region “the Galápagos of the East” based on our previous findings of an “evolutionary cauldron” of new and unique coral, shrimp and fish species (including an endemic walking shark!) during our 2006 Marine RAP survey of the park.
For a variety of reasons that we’ll explore later in this blog series, Cenderawasih Bay has been separated repeatedly during the last 15 million years of geological history, creating in essence a large marine lake within which the marine life has been able to follow its own evolutionary trajectory in relative isolation. As such, an unusually high percentage of the fish, corals and other life in the bay are now unique species found nowhere else on the planet.
But without question our main target of exploration is the population of whale sharks which appear resident in the bay throughout the year. While there are a number of other regions of the world which offer outstanding whale shark viewing — including the Galápagos, Belize, Western Australia’s Ningaloo reefs, and Donsol in the Philippines — in each of these cases the sharks are only resident for a period of one to three months before continuing on their long migrations elsewhere in search of food.
Dr. Stewart from HSWRI has made a career of investigating these migrations, using satellite tagging technology to reveal just how far these animals migrate. The situation with the Cenderawasih whale sharks appears quite unique in that they seem to be in the bay year-round. One current working theory is that Cenderawasih Bay functions as a nursery ground for adolescent whale sharks, which remain in the calm and protected bay until they are adults before leaving to migrate further afield. This seems to be supported by initial observations that the vast majority of the whale sharks observed in Cenderawasih are in the 5-7 meter (16.4-23 foot) size range.
During our trip, we’ll hopefully be applying satellite tags to five of these animals in order to gain a clearer understanding of their movements within the bay (and possibly outside of it) over the course of the year. We’ll also take photographs of as many individuals as possible, as whale sharks have unique spotting patterns that allow researchers to assemble a database of “identification photos” for each animal. This should allow us to start to get a better handle on the size of the population within the bay — a goal which our colleagues at WWF-Indonesia are particularly keen to achieve in order to better plan the management of this unique region.
I hear the plane with our team landing, so it’s time to run; check back soon for frequent blog updates on our progress!
Dr. Mark Erdmann is senior advisor to CI-Indonesia’s marine program.
PHOTO CAPTION: Whale shark photographed on a previous expedition in Indonesia.
PHOTO CREDIT © Burt Jones and Maurine Shimlock