Mahakam dolphins at brink of extinction
The Jakarta Post
The Mahakam, one of Indonesia’s mightiest rivers, is home to endangered freshwater dolphins in Kalimantan. Conservation group Rare Aquatic Species of Indonesia (RASI) estimates their number at 80. Pollution from the mining industry and logging has been largely blamed for their endangerment. The Jakarta Post correspondent in Balikpapan, East Kalimantan, Nurni Sulaiman, recently joined researchers and activists on a three-week trip along the Mahakam River to monitor the animals’ degrading habitat and conservation efforts.
Sailing upstream from the provincial capital of Samarinda to Kutai Kartanegara, some 75 kilometers to the northwest, we passed countless vessels of all sorts. In Kalimantan, a vast but sparsely populated island, rivers are just like busy highways in the more developed Java.
In downstream areas closer to the estuary, staggering coal-laden bulk carriers looked like clusters of floating hills from afar. Further upstream, in the area of Ulu in Kutai Kartanegara, vessels carrying mostly timber are headed for sawmills dotting the 980-km long river.
Locals and researchers fondly remember sighting groups of dolphins along the Mahakam River from the upstream Kutai region down to the estuary in Samarinda. That was a few decades ago, when traffic on the river was light. Today, it is teeming with vessels of all sizes that environmentalists partly blame for the dwindling population of the treasured river dolphins.
At Sebembam, Kutai Kartanegara, The Jakarta Post and researchers sighted a pod of about 16 dolphins. The thundering noise of an oncoming bulk freighter scared and sent them in disarray.
Danielle Kreb, a senior researcher and scientific advisor with RASI, said the heavy presence of vessels and the noise they make has greatly contributed to the endangerment of the rare species. Every time a vessel approaches, the dolphins dive deep into the river. “They don’t rise up as often as they used to; they have experienced a change in diving pattern.”
Research shows that the animals have gone through behavioral changes because of the noise pollution and deteriorating water quality due to the dust and debris from the passing vessels. Untreated waste from industrial activities along the Mahakam and its numerous water sources has exacerbated the predicament. The busy traffic not only causes stress to aquatic life but also damages the river’s ecosystem, especially in narrow creeks where fish spawn.
The prolonged stress reduces the animals’ immunity and contributes to ailments and premature deliveries, changes in migration patterns and avoidance of excessively busy spots like tributaries. The latter results in fiercer competition for space and food. Besides that, the dolphins are at risk of being struck by speedboats, as excessive noise confuses their sonar system.
The underwater noise pollution from the busy river traffic is worst at confluences. One of the most affected is the Kedang Kepala tributary in Kutai Kartanegara, which is known as one of the few remaining Mahakam dolphin habitats. “This is very worrying,” said Kreb.
During their trip, the researchers focused on several important spots, such as those at the Kedang Rantau, Sabintulung, Tunjungan, Kedang Kepala and Siran estuaries. To our delight, dolphins were sighted in various spots along the way.
Kreb noted that the number of Mahakam dolphins in the Kedang Kepala River had dropped by 50 percent since pontoons began “invading” the area two years ago. The river has sustained damage to its banks, because it is too narrow for large vessels to make L- or U-turns.
She expressed her wish that vessels be banned in the area, because it has been earmarked as a priority conservation area for not only water but also wasteland ecosystems.
“Residents have told me that the Mahakam’s current used to be stronger. This means the water quality has deteriorated. The loss of vegetation at the riverside has deprived small fish of spawning grounds. All this has happened over the past two years, since the strong presence of vessels began in the area,” Kreb said.
Lucky day: Rare freshwater dolphins are sighted in a quiet corner of the Mahakam River. Busy water traffic and toxic waste from mining and logging activities have been attributed to the animal’s dwindling population.(Courtesy of RASI)The Mahakam, one of Indonesia’s mightiest rivers, is home to endangered freshwater dolphins in Kalimantan. Conservation group Rare Aquatic Species of Indonesia (R...
PREMIUM Lucky day: Rare freshwater dolphins are sighted in a quiet corner of the Mahakam River. Busy water traffic and toxic waste from mining and logging activities have been attributed to the animal’s dwindling population.(Courtesy of RASI)The Mahakam, one of Indonesia’s mightiest rivers, is home to endangered freshwater dolphins in Kalimantan. Conservation group Rare Aquatic Species of Indonesia (R...
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