We have just finished our latest adventure, a trip tagging whale sharks.
Indonesia's Cenerwasih Bay is a place where whale sharks come to feed on small fish falling from the nets of “Bagans”. “Bagans”are boats of about 10 to 15 meters(33 to 49 feet) long and larger with outriggers. Underneath there are large nets that are lowered at night, then bright lights are turned on to attract fish. At predetermined times the lights are turned off and the nets raised along with the fish trapped within them. As the nets rise small fish overflow or escape through holes in the nets. Whale sharks normally feed mostly on plankton but began coming to feed on those fish. Eventually the fishermen began feeding them additional fish and the added source of food available has attracted a larger number of sharks and established a place where tourists can reliably find whale sharks to interact with. We have dove/snorkeled with as many as 7 at one time. They are friendly and appear to actually enjoy people interacting with them.
There is still much unknown about whale shark behavior and migration habits, therefore in an effort to gain further knowledge some are being tagged with electronic devices that record such data as depth, temperature, time, etc
There are currently 3 types of tags being used. The first is attached to the body near the dorsal fin by injecting a small anchor under the skin that is connected to it. That type must be monitored by someone approaching the whale shark and reading data with a device similar in function to a bar code reader.
The second type is also attached near the dorsal fin but is designed to break free after a programmed length of time. Once free, it will float to the surface and upload its stored date to scientists via the satellite.
The third type is new and employs the latest technology to store more data at higher resolution. It has batteries that keep it operating for 6 months. When the whale shark occasionally surfaces, a set of sensors detects that the fin is out of the water, the tag's transmitter turns on, and the stored data is uploaded to a satellite. It was this third type that was installed during this trip.
The installation of tags during our trip was performed by a team of local Indonesian scientists from “Conservation International”, University of Papua, and the National Park organization and was led by Doctor Mark Erdmann from “Conservation International”. Completing the task required coordination with the fishermen. When a whale shark appeared, it was lured into their net, the net was raised to near the surface, and the operation began. The dorsal fin of the shark has no nerves so attaching a tag causes no pain. They lay calmly while 4 holes were drilled through the fin and bolts attached the tag. Once tagged they were assisted with clearing the net and they swam away unconcerned, looking for more to eat. A total of five were successfully tagged.
It is always a very enjoyable experience interacting with these beautiful animals but this time it was an exceptional experience.