Jakarta – A total of 55 long-finned pilot whales (Globicephala melas) became stranded in the waters off Mbadokai Beach in Rote Ndao regency, East Nusa Tenggara, with nearly half of the animals later dying as rescuers struggled to return them to the sea.
Imam Fauzi, head of the Kupang office of the National Waters Conservation Agency (BKKPN), said local residents first spotted the whale pod in shallow waters of the beach in Southwest Rote district on Monday night.
"Residents attempted to guide the whales back to deeper waters, but the animals repeatedly swam toward the shore until they eventually became stranded," he said on Tuesday as quoted by Kompas.id.
Several whales were also caught in fishing nets installed by local fishermen near the beach.
Imam said the stranding may have been caused by strong currents. He explained that pilot whales travel in tight groups and rely heavily on the leadership of a dominant individual.
"If the leader becomes stranded, the rest of the group may follow and end up beaching themselves as well," he added.
Imam said local residents, along with police officers and personnel from the Indonesian Military (TNI), worked throughout the night to slowly push the stranded whales back into deeper waters. However, rescuers struggled due to the animals' heavy weight.
Rescuers eventually managed to save 34 whales, while 21 others died from injuries and dehydration.
Southwest Rote Police chief Second Insp. Subur Gunawan said the rescue team used fishing boats and limited equipment to escort the animals until they were safely back in deeper waters.
"The effort required patience and close coordination between authorities and the community. It took several hours to complete the operation as the whales had to be guided slowly to prevent them from returning to shallow waters," he said.
Rote Ndao Police chief Sr. Adj. Comr. Mardiono praised the local community, especially fishermen, for their active role in rescuing the protected whales. He said it was the largest such rescue he had witnessed in the area.
"We are grateful to the fishermen who helped save the whale pod today. Their active participation reflects their commitment to save this protected species," he said.
BKKPN's Imam said the carcasses of 21 pilot whales were buried on Mbadokai Beach on Tuesday afternoon to prevent environmental contamination and avoid foul odors.
The burial, which involved BKKPN officials, police officers and local residents, was completed around 8 p.m.
"Before burial, the team examined each whale and recorded its measurements. The smallest was about 2.4 meters long, while the largest measured 5.1 meters," he said, as quoted by Kompas.com.
Imam added that BKKPN Kupang will continue monitoring the area for any further stranding of whales.
Yuvensius Stefanus Nonga, executive director of East Nusa Tenggara Branch of the Indonesian Forum for the Environment (Walhi) has called on the government to conduct a comprehensive scientific investigation into the Rote Ndao pilot whale stranding, involving independent researchers, academic institutions and civil society organizations.
"This is not simply a wildlife incident, but a serious warning about the growing vulnerability of East Nusa Tenggara's marine ecosystem. Mass stranding of whales should be treated as a signal of possible ecological disruption in the region," he said as quoted by national radio station RRI.
He explained that long-finned pilot whales are social mammals that rely on echolocation, a sound-based navigation system, for communication and orientation. Mass stranding incidents have often been linked to disruptions of this system.
Yuvensius said such disruptions can result from shifts in ocean currents, changes in prey distribution due to climate change and other environmental disturbances. Human activities, including underwater noise from ships, seismic surveys, and marine resource exploitation, can also interfere with whales' sensitive communication and navigation.
"All potential causes must be investigated thoroughly and transparently, especially given that East Nusa Tenggara lies along a major migration corridor connecting the Pacific and Indian oceans, used annually by multiple species of whales and dolphins," he said.
Both short-finned and long-finned pilot whales are generally listed as of least concern on the International Union for Conservation of Nature (IUCN) Red List. However, certain regional populations such as the Mediterranean subpopulation of long-finned pilot whales are classified as endangered or critically endangered.
In Indonesia, long-finned pilot whales are a protected species under the 2018 Environment and Forestry Ministry regulation.