This week, a group of CI communications staff are meeting in Bali to gather stories from our field projects in Indonesia and across the Asia-Pacific region. Follow their journey on CI’s Facebook, Twitter and Instagram pages.
A light haze hangs in the early morning air at the docks in Sanur, a small beach district of Denpasar city on the east coast of Bali. There, I gather with nearly 20 of my colleagues from across Asia, the Pacific and the U.S in excited anticipation of the long day of manta ray tagging ahead of us.
The trip to Nusa Penida, an island just east of Sanur, would be relatively short were it not for the rough chop of the open ocean reminding us who is in charge. After more than a half-hour cruising through the rolling waves from the Indian Ocean, we arrive at Manta Point, a dive site flanked by cliffs about 200 feet [61 meters] high. Below us await corals, reef fish and (hopefully) manta rays.
Dr. Mark Erdmann and Abraham “Abam” Sianipar are the scientists in charge of affixing these satellite tags to the massive animals. Working in partnership with S.E.A. Aquarium and the Indonesian Ministry of Marine Affairs and Fisheries, they have been hard at work over the past year, putting 28 tags on mantas. Today, they are hoping to deploy their final two tags.
“This research came about thanks to the Indonesian government’s decision to give full protected status for both species of mantas,” Abam tells me. “There is a lack of knowledge about the movements of manta populations through Indonesia. We developed this program to document their movements and to provide the government with data that can be used to better manage the mantas.” (Learn more and see cool manta footage in the video below.)
The tags are no bigger than a tennis shoe, but cost over US$ 6,000 apiece. They can lock on to a GPS satellite in 2.5 milliseconds when a tagged manta surfaces. These tags can transmit important data — including temperature, depth and location — that enable scientists like Mark and Abam to better understand the life of mantas in Indonesia.
The satellite tags could shed new light on the details of manta lives, such as where they breed and exactly how far they migrate. The tracking information can also show scientists where these fish are likely to cross paths with communities that are known to hunt them. Learning this knowledge is critical in order to protect mantas — as well as the local people that benefit from them.
Manta rays are a valuable asset in Indonesia: Over the course of its lifetime, a single manta ray can generate $1 million in tourism revenue.
“I bring people to this island to see another world, an underwater world,” says our guide, Kadek Budiarta. His business, and the business of every tour operator, depends on tourists who want to come see mantas in the wild. These fish are essential to their livelihoods.
In fact, they are so valuable that the government of Indonesia, through its Ministry of Marine Affairs and Fisheries, has made its entire exclusive economic zone — an area nearly twice the size of India — a sanctuary for both species of manta.
But even though mantas are protected and Indonesian officials have cracked down on poaching, they are still under threat. In the past two decades, a market has developed in China for manta ray gill rakers as a cure-all for everything from cancer to infertility, despite having no curative properties and not being considered a formal component of traditional Chinese medicine. As a result of this market, some Indonesian communities still target the fish.
We arrive at Manta Point, gear up and are over the side of the boat into the clear water. Mark explains we are at a manta “cleaning station,” a place where the mantas allow small fish to “clean” their skin and gills of parasites. “You typically get bigger adult females coming in, often big pregnant ones,” Mark says. (Like many shark species, mantas give birth to live young.) “These large females are generally very calm while being cleaned, making them easier to tag.”
After a few moments, a big female reef manta ray trailed by four male suitors swims right below us. These are the smaller of the two species of manta ray — reaching about 5 meters (16 feet) at their largest — but looking at the fish below us, I would call them anything but small. For the next half-hour these five manta rays, the largest of which is about 4.2 meters (13 feet) from tip to tip, circle around us as we interlopers look on in amazement.
While we watch, Mark explains that this behavior is the mantas’ mating courtship, where several males follow a female to form a “train.” Watching this elegant dance unfold, it’s hard to understand how these graceful and curious fish ever got saddled with the nickname “devil fish.”
Even though mantas are social and often interact with snorkelers and divers, tagging them can be difficult. Abam uses a modified pole spear and aims for a small area toward the posterior of the manta that is just off-center of the crease of the wing. If he misses, the manta will swim away because, let’s face it: Nobody likes getting poked with a stick, even if it’s for science.
As most of our group returns to the boat, Abam and Mark take advantage of a moment alone with the mantas to successfully tag the large pregnant female.
We move on to the next dive location in search of the manta ray that will carry the last of our 30 satellite tags, bringing us another step closer to expanding humanity’s knowledge of these magnificent, mysterious creatures.
Kevin Connor is CI’s media manager.