Expert say underwater human activities interfere with navigation of marine mammals but more research and data needed to point cause of cetaceans stranding.

It was supposed to be a mundane technical map like any other. The map showed grids in the waters south of Flores Island to Lembata Island in East Nusa Tenggara. From above, the grid looks like a fence or fishing net spreading over the Savu Sea.

The map in question can be found on the ESDM OneMap, a geospatial platform run by the Ministry of Energy and Mineral Resources. The grids represent routes taken by vessels that make at least 31 two-dimensional seismic surveys, which use low-and medium-frequency sounds to map the southern seabeds of Flores, Adonara, and Lembata. 

The waters are known as the winter migration route of whales and other species from the cetacean infraorder, which rely on the frequencies for communication, hunting, and navigation. Today, an increasing number of these mammals are getting stranded on these islands’ shorelines. Many observers have linked the phenomenon to similar seismic surveys, but the jury is still out. 

Cetaceans migration route Jakarta Globe

A noisy sea

Hadi Wijaya, the head of the Marine Geological Institute, was only on his third day on the job at the Marine Geological Institute when he took an online meeting with the Globe on Aug 11. 

Under the auspices of the energy ministry, his office provides seismic survey services, conducts marine geological mapping, and manages infrastructures needed in marine geological mapping and seismic surveys.

“Implementing a seismic survey is more complicated than shown on the map,” Hadi said.

Imagine a 62-meter seismic survey ship traveling at four knots (7.2 km/h) from north to south before stopping in the middle of the sea. The boat then returns to land, shifting west or east, before crossing north-south again.

While traveling, the vessel shoots “periodic airgun fire producing underwater sound waves” to produce a graph showing the seabeds, Hadi said. By “periodic,” he meant a 10-minute interval between shots from end-to-end. 

The vessel will change course after completing the north-south seismic survey trajectory. The seismic survey ship is now traveling east to west in the same area. The seismic survey vessel stops in the sea, anchors, and heads east-west. 

Hadi said the ship needed repeated trips to produce a detailed map of “the underwater sedimentary structure.” 

Sea noise is indeed one of the stranding causes. The source could be from an underwater seismic survey or ship sonar, which ultimately interferes with the navigation of marine mammals.

Pingkan Katharina Roeroe, coordinator of the Marine and Fisheries Ministry’s Area and Fish Species Utilization Group

Besides the seismic survey routes, OneMap does not reveal other details about the survey in the Savu Sea or elsewhere in Indonesia. There is no information about the contractors, exact coordinates, or the period of the survey. Each survey line’s activity status is unknown.

“The lines drawn on the map of the southern part of Flores Island to Lembata Island are seismic survey lines that are no longer active,” said Eko Budi Lelono, Head of the Geological Agency of the Ministry of Energy and Mineral Resources, in an interview on August 10. 

He added that the last seismic survey carried out in the Savu Sea was recorded in 2007, “or two years before the declaration of the Savu Sea as a Marine Protected Area.”

The Indonesian government declared the Savu Sea a Marine Protected Area—covering 3.35 million hectares of waters in East Nusa Tenggara—on the sidelines of the World Ocean Conference in Manado, North Sulawesi, on May 13, 2009. With this addition, the total area of the Indonesian Marine Protected Area becomes 28 million hectares.

Savu Sea ecosytem and biota Jakarta Globe

Following the declaration, the government has imposed several restrictions on “unsustainable human activities in the Savu Sea National Park,” Pingkan Katharina Roeroe, the Coordinator of the Marine and Fisheries Ministry’s Area and Fish Species Utilization Group, said during a webinar, “Harmonising Management of Conservation Areas and Indonesian Archipelagic Sealanes,” on July 31.

She listed blast fishing and marine debris as unsustainable human activities but did not mention seismic surveys in the same category. 

The seismic survey matter came to light in a session before the end of the webinar. Asked by a participant whether seismic surveys negatively impact cetacean stranding in the Savu Sea, she answered: “Sea noise is indeed one of the stranding causes. The source could be from an underwater seismic survey or ship sonar, which ultimately interferes with the navigation of marine mammals.”

Limited resources

Pingkan said that there was a need for more in-depth research to determine whether or not seismic surveys are a source of disturbance to the cetaceans’ navigation system. Currently, “we are conducting more technical guidance in evacuating stranded cetaceans instead of in-depth research into the causes of the stranding incidents,” she said.

Research funds in the Savu Sea conservation area “source from the State Budget,” said Imam Fauzi, Head of Kupang Marine Protected Area Agency (BKKPN Kupang). His office “receives only a small amount of research funding” annually. At the same time, “few researchers have focused on cetaceans in East Nusa Tenggara.” He did not specify the funding or the number of cetacean researchers.

On a separate occasion, Putu Liza Kusuma Mustika, a member of the International Union for Conservation of Nature (IUCN) Cetacean Specialist Group, agreed that there are few marine mammal researchers in Indonesia. “We have fewer than 20 researchers who are actively doing marine mammal research correctly,” said Liza, who started researching marine mammals in 2001.

She felt compelled to underline the word ‘correctly’ because “a researcher can publish their findings on marine mammals, but they do not correctly conduct the research.” In addition, “the willingness of various parties to receive training related to cetaceans is still minimal in Indonesia,” the 48-year-old researcher said. 

“If we have five other qualified researchers to be added to those less than 20 researchers that would be nice. More would be great, of course, but the quality is the first condition,” Liza said.

Knowledge and training in the coastal area are essential, said the adjunct researcher at the College of Business, Law and Governance, James Cook University, Australia, “before we jump to the human activities factors in the open sea which, for years, have been contributing to cetacean stranding.” She continued that some of the greatest attention “has been paid to the sounds produced by offshore human activities.”

Overlapping frequencies

The sea, where marine mammals inhabit, has background noise in the 1-1000 hertz (Hz) range. It’s the range “derived from natural sources and also increasing anthropogenic inputs,” wrote Ross Compton et al. in their findings, “A Critical Examination of Worldwide Guidelines for Minimizing the Disturbance to Marine Mammals during Seismic Surveys.”

“Seismic surveys and cetaceans both use low to medium frequencies,” said Liza. Baleen whales produce sound typically at 10 Hz to 1 kHz. Toothed whales use frequencies within 10-150 kHz. Dolphins make sounds at around 200 Hz to 150 kHz. The pulses of the seismic survey lie within 10 Hz–10 kHz. She continued that the seismic survey and whale frequency “have the longest frequency overlap among others in the category.”

The dominant frequencies of airgun pulses lie within the 0-120 Hz range, “though there are significant levels of high-frequency sound up to 20 kHz also produced by the pulses,” wrote Campton et al. 

In a written statement, the Marine Geological Institute’s Hadi said that “the output frequency of the airgun is around 3–200 Hz.” He said the airgun, a tube-wave with a valve, will be opened at a specific time to produce a sound explosion between 15 and 24 decibels (dB). Normal human conversation is about 60 dB. Whispers are 30 dB.

Meanwhile, Danielle Kreb, the scientific program advisor at non-profit organization the Conservation Foundation for Rare Aquatic Species of Indonesia, said that “seismic test blasts are up to 256 dB – and are pumped from the surface of the ocean all the way to the seabed, every 3 to 6 seconds, for 24 hours a day for weeks or even months.” That is the “sound can be heard at the core of the blast.”  

The sound, the marine mammal researcher added, “is louder than NASA’s Saturn V rocket which was 204 dB. The Hiroshima bomb was 256 dB,” she said.

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In several seismic surveys conducted off the Indonesian coast, the office led by Hadi acts as a service provider, including a survey vessel equipped with all the systems needed for the survey and supporting data. The ministry’s term for such cooperation is “public service bureau cooperation,” or BLU.

Hadi said the cost incurred by a company to conduct a seismic survey could reach Rp 1 billion ($67,000) per day. Surveys can take up to two weeks.” The rental fee for Geomarin 3, a seismic survey vessel owned by Hadi’s office, is calculated daily.

“The vessel rental cost is approximately one-fifth of total costs spent on an actual day. However, sometimes the rental fee also takes into account the risks and disruptions of work in the related locations,” Hadi said. He did not specify the types of risks and disturbances nor the presence of cetaceans’ possible count in the categories.

While checking the data sheets his staff prepared before the interview on August 11, he continued, “It is the company that pays the fees in the BLU contract, not us.” The cost is enormous. If the data leaks, what will their profit be?”

Asked whether the ‘related locations’ he mentioned included the Savu Sea and, if so, whether there was seismic survey activity this year, he replied, “It depends on the exact location.” If a company targets an exploration area that still lacks data to strengthen its plan to develop an oil and gas working area, it will probably conduct a joint study. “Again, we don’t have all the data. “

A joint study is one of the initial processes in underwater oil and gas exploration. It combines literature and data from several previous survey reviews, accompanied by implementing the latest series of seismic surveys. The joint study will help a company to be able to narrow the area of ​​oil and gas exploration, which, in the end, will also have an impact on their spending.

“The last time a joint study was conducted in the Savu Sea was in 2021, but it was not accompanied by seismic surveys. Only a literature review,” said Eko in an interview on Aug 9. “Even if there was a seismic survey in the joint study in the Savu Sea, we must first coordinate with BKKPN Kupang,” said Eko, who, like Hadi, repeatedly referred to data sheets his office prepared beforehand. 

BKKPN Kupang’s Imam stated that he had not received any information regarding the conduct of seismic surveys in his working area. “I had never received any letter regarding the plan to carry out a seismic survey in the Savu Sea,” said Imam, appointed the highest authority in his office in March 2021.

If his office receives such a letter, “we will, in return, share information about marine mammals crossing the Savu Sea along with the buffer [zones] that the seismic survey operator must avoid.” Therefore, they would not disturb the Savu Sea conservation area. “He stopped for a second before continuing, “let me check again with my secretary.” 

Two days passed when he sent a short sentence through an online chat application: “We never received such a letter.”

Speaking via Zoom from Queensland, Australia, Liza prompted, “At this point, we are discussing the problems that occur in our open sea. We haven’t taken all the interactions to the high seas level, a vast ocean that is not under the jurisdiction of any country. All we can do is to fix the policy in the open sea.” 

In that way, “cetaceans, at the very least, will be able to cross safely along Indonesia’s territorial waters before reaching the high seas,” said Liza. 

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Divergent responsibilities

The Denpasar Marine and Coastal Resources Management Agency recorded 30 incidents of cetaceans stranded in East Nusa Tenggara between January 2018 and May 2022. According to data published by the agency, 6 of the 30 incidents occurred between January and May 2022.

“Of all the districts in East Nusa Tenggara, Alor recorded the highest number of stranding incidents since 2018,” the agency head, Permana Yudiarso, said. 

The most stranded species in the 30 incidents were the short-finned pilot whale (17), followed by the pilot whale and sperm whale (11 each) and the dolphin (6). Sabu-Raijua was the district with the highest number of cetaceans stranded since 2018. 

“Every year, there are always occurrences of cetaceans trapped in narrow trenches before, in some cases, stranded onshore in the Savu Sea coastal area,” said Amang Raga, a former marine mammal program coordinator at the non-profit organization Jakarta Animal Aid Network (JAAN). 

The ethologist—a scientist who studies animal behavior—who lives in Surabaya, East Java, has flown several times to lead the evacuation of stranded cetaceans in East Nusa Tenggara. “The furthest and most sudden trip occurred in October 2014, when five blue whales washed ashore on Lembata Island,” Raga recollected. 

At the time, he had to travel from Natuna Islands, the outermost northern border of Indonesia, to Lembata. “It was the most rushed trip I ever made,” he brought back the memory with a laugh. Gaining a great deal of experience during a series of evacuations, he recalled the time he had to meet with Indonesia’s eastern indigenous people. 

Communities in several coastal, traditional villages believe the body parts of cetaceans that wash ashore—alive or dead—should be cut at the earliest opportunity. Like the Lamalera people, they believe the stranded cetaceans are ancestral gifts. 

If they don’t eat the meat of the stranded cetaceans, “the ancestors will be angry and curse the community in the village through crop failure [of crops and fish catches] for a long time,” said Raga, who studied ethology in Chiang Mai, Thailand. 

When this happens, performing necropsies, which provide crucial and valuable insights into their health and potential impact on human activities, is becoming increasingly difficult. “The only thing I could do was glance at the stranded cetaceans’ bodies,” said the 45-year-old ethologist.

For example, said Raga when interviewed on August 21, “Are there bruises like the shape of an island map on their bodies?” If there are, it means that the cetaceans were stranded due to being affected by the seismic survey’s acoustic waves.” The low-frequency acoustic waves, he continued, “cause shock on whales passing near their airgun detonation.” 

“Sometimes I wish human activities were not one of the factors in the cetaceans’ stranding. But we can’t ‘close our eyes, can we?” said Raga, who also led the evacuation team for five blue whales stranded in Waienga Bay, Watodiri village, Lembata in October 2014. 

He pinned a tagging device on one of four blue whales stranded in the bay before they made it out of an “S”-shaped shallow sea trench with only one exit to the deep waters. Raga always returned to Waienga every year in October after that incident. 

“Every year in October, the tagging monitor detected signals from the tagging device that I attached to a blue whale’s body, indicating its movement around Waienga,” Raga said, before continuing, “From that, I knew it was on a pilgrimage.”

The blue whale swam back to the same place in the same month when it and its family had been trapped in a narrow trough, leaving behind a member of its family whose bones now stand as a monument at the Watodiri village’s entrance.

This story was first published in Jakarta Globe on 11 September 2022 and produced with the support of Internews’ Earth Journalism Network.

About the writer
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Anastasia Ika

Anastasia Ika is a researcher-writer based in West Java, Indonesia. Ika tarted working as a print media journalist in 2009 and she loves to write human-nature interaction stories. She is now working as...

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