Off Sri Lanka’s southern coast, where the ocean drops into an indigo trench, a blue whale dives below the surf, her gargantuan size belying the grace of her movement through the silent water. Her hymn of clicks and whistles resonates through the deep, calling to her young calf.
Her kind has lived here for generations, at the pinnacle of a food chain that begins in the ocean’s depths. But her world is different from that of her ancestors. Overhead, giants of another kind carve across the sea – ships, hundreds of them, their steel hulls an invisible threat. This female had grown accustomed to the ships’ presence. But one spring morning proved to be her last.
In March 2012, the lifeless body of an 18m female blue whale was found in the harbour of Colombo, Sri Lanka’s largest city, a deep gash exposing her left flank. She had collided with The Quartz, a container ship, and was discovered draped over its bulbous bow, a spear-like protrusion at the front of the vessel. Eyewitnesses reported no smell, suggesting she had died recently.
A team disposed of the corpse out at sea but, two days later, the remains washed up on a beach south of Colombo. The dead whale was now rapidly decomposing: its flesh had turned a putrefied grey, its carcass flecked with lacerations left behind as birds pecked through the carrion. This time, the smell was unmistakeable. The case was later documented by Asha de Vos, a prominent marine biologist in Sri Lanka. The collision alerted conservationists to the dangers whales face in the seas surrounding the island nation.
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A changing route
A cosmopolitan species, most blue whales embark on seasonal migrations through every ocean except the Arctic, never staying put for long. But in the northern Indian Ocean around Sri Lanka, a remarkable confluence of meteorological and geological quirks enables these giants, plus a menagerie of other species, to thrive year-round.
Before calling into port in Colombo, The Quartz, like many vessels, traversed Sri Lanka’s southern coastline. Since 1980, that stretch of water has hosted one of the world’s most heavily trafficked shipping lanes, a funnel for maritime trade connecting Asia with the Arabian Sea, and onwards to the Middle East and Europe.
More than 100 merchant ships ply these waters daily. Over a decade after The Quartz struck that whale, I saw some of them from a vantage point on one of the beaches flanking Mirissa, an idyllic fishing village on the southern shore. They drifted across the horizon, almost peaceful despite their size. It was impossible to see the deadly obstacle course beneath them, impossible to know of the graveyard of giants in their wake. From the brainy sperm whale to the elegant Omura’s and the inquisitive Bryde’s, many whale species call the waters around Sri Lanka home. But none are more iconic than the island’s blue whales.
These leviathans journey the world’s oceans along seasonal migratory routes. In summer, they feed near plankton-rich poles and, when temperatures dip, they travel to warmer climates to breed and give birth. Most blue whales follow these patterns, save for those encumbered by age or malady. But Sri Lanka’s families are peculiar, being among the few of their kind to stay close to home all year round.
“In the northern Indian Ocean, most blue whales are unusual and stay close to the equator,” says Russell Leaper, a whale scientist at the International Fund for Animal Welfare, who has consulted on whale welfare in Sri Lanka for more than a decade. Their aversion to wanderlust, he explains, comes down to the waters around the island representing the whale version of an all-you-can-eat buffet.
Easy pickings
A few kilometres south of Sri Lanka’s coast, the seafloor plunges hundreds of metres deep. Here in the ocean’s depths, a place almost no light can penetrate, decomposing organic matter accumulates in the form of nutrients such as nitrates and phosphates. This material might languish on the seafloor were it not for the powerful columns of water that regularly rocket it to the surface.
Between the island’s two monsoon seasons, Sri Lanka is constantly buffeted by interchanging wind patterns. In summer, hot and humid air sweeps in from the Indian Ocean to the south. In winter, cool and dry winds from the Himalayas descend from the north. The contrasting air temperatures accelerate wind speeds and create perfect conditions for upwelling, the process that shifts warm surface water offshore and replaces it with cooler water from the deep sea.
These swirling currents ferry a smorgasbord of nutrients to the upper layers of the ocean, where tiny microorganisms consume them. Among these are krill – small, shrimp-like crustaceans and a staple food for blue whales. Floating near the surface, shimmering like dust caught in sunlight, krill in Sri Lanka have adapted to thrive in tropical seas thanks to the strong upwelling cycles, and blue whales are present year-round to gobble them up.
New dangers for whales
Few things threaten blue whales; humans are one of them. The spread of commercial whaling in the early 20th century destroyed global numbers from nearly 300,000 to a few hundred as whalers harvested the animal’s blubber and oil for everything from lamp fuel to bars of soap. It took decades to regulate whaling and partially restore blue whale populations but, as technology and trade have connected the seas like never before, new dangers are emerging for these gentle giants.
“Generally speaking, collisions with ships and entanglement with fishing gear are now the leading human-induced threats to whales,” says Anna Nisi, an ecologist at the University of Washington, whose research focuses on how animals navigate human-dominated areas.
A 2024 study authored by Nisi produced the first model-mapping of where shipping traffic intersects with whale movements. She discovered that, while the ocean is no longer a whaler’s hunting ground, it remains a battlefield: 92 per cent of known whale ranges overlap with shipping routes, now a ‘primary threat’ to the creatures. The northern Indian Ocean surrounding Sri Lanka ranked among the riskiest places for whales, particularly blues, to navigate.
Nisi’s analysis relied on predictive modelling, using shipping and whale movement data to estimate where collisions are likely to occur. It cannot tell us exactly how many whales have been struck around Sri Lanka. But perhaps nothing can.
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Beached whale carcasses, like the female that collided with The Quartz, are the exception rather than the rule. After only a few days, a deceased whale’s remains lose buoyancy and sink to the seafloor, a phenomenon known as whale fall. Condemned to the ocean’s depths, the creature’s flesh and skeleton create miniature ecosystems where other marine life can thrive. But to humans, whale fall only means a graveyard in the abyss. The untold numbers that lie there died silently and unseen, the reasons for their demise buried with them.
The true rate of ship strikes, and resultant mortality, is a black box of unknowns. Sri Lanka’s reported share of injury or death-causing strikes might be only 20 to 30 per cent of the total, says Ranil Nanayakkara, a conservation biologist in Colombo, based on his 2017 survey of whale deaths. Fish stock assessments off the USA’s west coast have put the rate of detection for blue whales colliding with ships even lower, at only 2 per cent.
Rerouting ships
For more than a decade, de Vos, Leaper and other conservationists have petitioned the Sri Lankan government to reroute ships from the current shipping lane, which stands 8-10km from the island’s southern coast. In 2023, several bodies filed a proposal with the International Maritime Organization, a UN agency responsible for marine transport, advising a new lane 27km offshore. Research has found that this adjustment could cut collision risk by 95 per cent.
Under the proposal, vessels calling at ports would continue on the current route and ships transiting through Sri Lankan waters would take the new lane. While the share of ships docking changes throughout the year, it averages around 15 per cent, according to Leaper.
But to advocates’ dismay, the Sri Lankan government rejected the proposal. In a statement, officials questioned the lack of data on whale collisions and argued that placing vessels further from navigational infrastructure and well-charted seabeds represented a safety concern. In 2019, authorities were wary of the potential economic impact a new lane would have on ports.
A missing endorsement from the government means many legal, insurance and logistical hurdles to a new lane remain uncleared. But in an encouraging sign for Sri Lanka’s whales, similar measures elsewhere have succeeded without a helping hand from government.
A simple truth is that companies don’t want their ships to be running into whales, says Sean Hastings, an officer with the USA’s National Oceanic and Atmospheric Administration. In 2014, Hastings founded Blue Whales and Blue Skies, an initiative that incentivises shipping companies to reduce speeds while transiting close to California’s coast, a popular migratory corridor for blue whales and a collision hotspot.
Hastings has worked with de Vos to explore how similar initiatives could work in Sri Lanka, where consensus is building even without the government’s help. In 2022, MSC, the world’s largest container shipping company, began rerouting its vessels to journey 27km from Sri Lanka’s shore. A few months later, Wallenius Wilhelmsen, another cargo giant, made the same call.
More than 50 companies have signed on to navigate more cautiously in these zones, which Hastings reckons has reduced whale-strike risk by nearly 60 per cent. Three years ago, the programme did away with financial incentives such as awards and lower docking fees, instead focusing exclusively on positive recognition for participating companies, a momentum-based strategy that Hastings says is responsible for rising compliance. “Whales are the best messengers to tell this story,” he says. “Everyone, including ship captains, cares about whales.”
Since these announcements, a third of ships transiting south of Sri Lanka have opted to move further out to sea. That share rises to more than half when it comes to the largest and fastest ships, according to Leaper. More unilateral decisions from companies are likely in the coming years, he adds, possibly amounting to a “new traffic scheme by default”.
In the meantime, a unique family of blue whales will share their home with silent killers. An untold number will be struck. A few might wash ashore, their wounds a visceral testament for the world to see. But most will sink into the deep, their slow arcs never to breach the surface again. A haven for whales who chose never to leave the island may yet become their paradise lost.
Still, some will dive. They will duck below keels, twist around propeller blades and sing warnings to their kin when they detect ominous vibrations pulsing through the water. A mother will still guide her calf to the surface, threading pathways now lined with steel. For now, this sea is still her sanctuary, not yet her grave.
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Main image: a whale near Sri Lanka. Credit: Getty