A whale shark about 30 feet (9 meters) long was found dead on Parangkusumo Beach in Bantul Regency, Yogyakarta, Indonesia, on Oct. 18. Veterinarian Dwi Suprapti said it was the latest of eight whale shark strandings along Java’s southern coast in six months, VietnamPlus reported.
Rescue teams and environmental and fisheries experts arrived quickly, but the animal, which weighed more than 2 metric tons, died before it could be returned to the sea. Suprapti, who specializes in aquatic megafauna, said the cause of death has not been determined.
Experts hope necropsy results, combined with data on environmental quality and ocean conditions, will help explain the deaths, according to the report.
A feeding ground with a seasonal pattern
Indonesia’s Ministry of Marine Affairs and Fisheries says whale shark strandings are often recorded toward the end of the year. The waters off southern Java are a migratory route and feeding ground for the species.
Seasonal upwelling, in which cooler, nutrient-rich water rises to the surface, can lower sea surface temperatures and feed growth of shrimp and anchovies. How much those conditions have to do with the strandings still needs more research, the report said.
What a decade of records shows
Iqbal Herwata, senior manager of species conservation at Yayasan Konservasi Indonesia, cited 115 stranding events involving 127 whale sharks across 23 of Indonesia’s 38 provinces from 2011 to 2023. That tally comes from a 2025 study in Scientific Reports. West Java and East Java logged the most events, the VietnamPlus report said.
The institute’s release on the study says more than 70% of stranded animals were juveniles measuring 13 to 23 feet (4 to 7 meters). The paper partly attributes the rise in cases after 2020 to greater awareness and reporting, so the numbers may not reflect a purely real increase.
Those figures end in 2023 and do not include this year’s cases.
Why Indonesia matters for the species
Whale sharks are classified as endangered worldwide, and their population is estimated to have fallen 50% to 70%. Indonesia sits on a key migratory corridor linking Australian waters with areas south of Java, so what happens there affects regional conservation efforts, according to the report.
For Java, experts are looking to necropsy findings and ocean data for answers.
Source: Vietnam+ (VietnamPlus), Konservasi Indonesia, PubMed Central / Study: Scientific Reports
