Bali searches for answers after unusual whale strandings

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Bali, Indonesia – An unusual series of whale strandings has raised concerns in Indonesia, with three of the huge mammals stranded in Bali since early April.

It all started when on April 1, the rotting carcass of an 11-metre-long (36-foot) Bryde’s whale was found on a beach on Bali’s southwest coast.

Then last Wednesday, a live 60-foot sperm whale was found stranded on a beach in the southeast. The locals managed to push it back into the sea, but hours later it stranded on another beach, where it died.

The most recent event occurred over the weekend when the carcass of a 17-metre-long (56 ft) sperm whale — a deep-sea species that strands infrequently — was discovered off Bali’s southwest coast.

The events are part of a wider phenomenon that has seen 21 unexplained whales stranded across Indonesia since the beginning of the year, the Ministry of Fisheries and Marine Affairs said. They include the partial carcass of a 10-meter sperm whale that washed up on Bali’s southern coast on Jan. 19 and the remains of a 10-meter sperm whale found floating off the coast of the Kangean Islands, a small archipelago 120 km (75 mi) miles) north of Bali, on Monday.

Permana Yudiarso, who has been coordinating the government’s response to marine mammal strandings in Bali since 2012, said the frequency of recent strandings on the island was abnormal.

“Last year we had nine incidents in Indonesia. Normally we have less than 20 each year. But three cases in a week in Bali alone – it is quite worrying,” Yudiarso, who is the head of the Bali Office of Coastal Resource Management at the Ministry of Fisheries and Marine Affairs, said. to Al Jazeera.

Post-mortem examinations are being conducted on samples taken from two of the three whales found on the island. But even if the results are made public later this month, they are unlikely to provide a definitive answer to the spate of incidents.

Veterinarians examine the remains of one of the sperm whales that washed up on Bali.  They wear white protective suits.  The waves lapping at their feet.  The whale's teeth are clearly visible
A team of veterinarians took samples from the remains of the sperm whale on Sunday [Dicky Bisinglasi/AFP]

Some wildlife activists point the finger at plastic. Indonesia is the second largest source of marine plastic pollution after China, according to Indonesia’s coordinating Ministry of Maritime Affairs.

“Plastic pollution, when plastic is found in whales’ stomachs, and noise pollution, when the sonar the whales use for navigation is compromised by underwater noise and they get confused and become stranded themselves, are two of the leading causes of death,” says Femke den Hare. , wildlife paramedic and co-founder of the Jakarta Animal Network.

In 2018, a sperm whale was found dead in the waters of Wakatobi National Marine Park, some 1000 km northeast of Bali, with 115 plastic cups, 25 plastic bags, four plastic bottles and two sandals in its stomach.

A smaller amount of plastic was also found in the stomach of one of the sperm whales that stranded in western Bali earlier this month. “We still can’t say if the cause of death was plastic. It could be a disease,” Yudiarso said.

Still, he noted that there was a pattern in the strandings, which are more common in the transitional period between the wet and dry seasons.

“We are in the middle of that period now,” said Yudiarso. “It could be related to the tropical storm we had in Java last month or a more recent storm north of Australia in the Timor Sea. We also can’t rule out the effects of underwater earthquakes – we have them all the time in Bali. There were two earthquakes on Monday morning and that may have disrupted the whales’ sonar.”

‘whale trap’

Sumarsono, the head of the conservation department of the Bali Natural Resources Conservation Agency, who like many Indonesians goes by only one name, shared an alternative theory.

“The south of Bali has many steep sloping tidal flats where the difference between high and low tide is extreme, creating a natural fall,” explains Sumarsono.

“Many marine animals become trapped close to shore and by the time they realize something is wrong, it is too late for them to return to the deep ocean. Bali is in the middle of the migration route between Indonesia and East Timor, so getting trapped is a more likely cause of death than disease. It is statistically unlikely that three whales would die of disease within a week.”

Then there’s the issue of rising sea temperatures caused by the burning of fossil fuels and the associated depletion of ocean oxygen levels from the uptake of carbon dioxide.

A study, published in 2019 in the scientific journal Nature Climate Change, warned that warming oceans is increasing the risks of extinction and decreasing the biological richness of the sea. “Multiple regions in the Pacific, Atlantic and Indian Oceans are particularly vulnerable to marine heatwave intensification due to the coexistence of high levels of biodiversity,” the study said. It identified Indonesia’s waters as one of the five most affected areas.

Ocean heat reached an all-time high in 2022.

Karen Stockin, a professor of marine biology at Massey University in New Zealand, said it was important to distinguish between climate change and regular marine heat waves — periods of abnormally high ocean temperatures relative to average seasonal temperatures caused by short-term weather events such as El Niño events.

“They’re very different, but they both have the potential to change the distribution of prey like squid, and that carries the risk that predators like whales that rely on squid change their distribution in response,” she said. “If changes in distribution move whales closer to shore, that could increase their risk of stranding.”

An aerial view of the stranded whale.  There are people walking around on the beach, a yellow excavator and a team of vets in white protective suits.  It's high tide.
Three whales stranded in Bali this month, but experts say the cause may never be known [Dicky Bisinglasi/ AFP]

Sumarsono noted that two of the three whales that last stranded on Bali had large amounts of squid in their stomachs.

But that’s not necessarily a smoking gun, according to Stockin.

“The most important thing to consider with strandings like this is that the causes are quite complex. It is seldom easy to pinpoint a single cause. In most cases, strandings are most often caused by a multitude of factors.”

Vanessa Pirotta, a naturalist who has extensively studied whale beaching in the Australian state of Tasmania, an island like Bali described as a natural “whale trap,” said the phenomenon remained largely a mystery.

“What makes the recent strandings in Bali even more interesting are the two very different species that have stranded: sperm whales have teeth and use high-frequency sonar to communicate and navigate, and Bryde’s whales, which are toothless and use low-frequency sonar. So each stranding can be completely independent and can happen for different reasons,” she told Al Jazeera.

“Maybe they are connected or it was just a bizarre week of coincidences where three whales got stranded on one island. Maybe something scared them. Maybe one of them died of old age or was sick, but it’s way too early to make that call. The results of the autopsy exams can help understand the causes and identify a connection, but that’s not a given. In short, we will probably never know what caused their deaths.”



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