Why Whales Swallow Plastic: The 2013 Terschelling Sperm Whale

On 29 July 2013 a young sperm whale, about 13.5 metres long, came ashore on Terschelling, one of the Wadden Islands off the northern coast of the Netherlands. Attempts to help it failed and it died on the beach. When the carcass was taken to the harbour town of Harlingen for a post-mortem, researchers linked to the Naturalis Biodiversity Center reported plastic in its stomach, and said such finds were becoming more common.

That single whale is a useful window onto a bigger question many readers ask: why do whales, which spend their lives far from shore, end up swallowing our rubbish, and how much harm does it do? The short answer is that plastic looks, moves and drifts like food, it cannot be digested, and in the worst cases it blocks the gut completely.

A dead sperm whale on a beach. Strandings like this allow scientists to examine stomach contents and look for the cause of death.

The Terschelling whale and what its jaw suggested

The Dutch whale had another striking feature: a large part of its lower jaw was missing. That detail connects to an old observation from the whaling era. Whalers killed hundreds of thousands of sperm whales over two centuries, and among them were animals with broken, twisted or missing lower jaws that nonetheless had full stomachs and appeared well fed. Squid recovered from sperm whale stomachs are also often whole, with few tooth marks.

From this, some researchers have proposed that sperm whales rely heavily on suction to draw prey into the mouth, rather than seizing it with their teeth. If that is right, a sperm whale hunting in the dark may take in whatever is floating near its target, which would make it as exposed to debris as a filter-feeding whale. The idea remains a hypothesis, but it fits the stomach contents found in many stranded animals.

A pattern, not an accident: sperm whale cases

The Terschelling animal was far from the first. A few well-documented cases show how long this has been going on and how varied the debris is.

• Southern Spain, 2012. A sperm whale of about 10 metres stranded on the Granada coast. A team led by Renaud de Stephanis, writing in Marine Pollution Bulletin in 2013, found 59 plastic items weighing close to 18 kilograms (almost 40 pounds), most of it sheeting from the vast greenhouses of Almería and Granada, plus rope, a hosepipe and two flowerpots. They concluded the whale died of gastric rupture after its stomach became impacted. (Some reports at the time placed this stranding in 2013, the year the study was published.)
• Northern California, 2008. Two sperm whales stranded in the region that year with large amounts of fishing net and other debris in their stomachs; one case was widely reported from the Point Reyes coast.
• Mediterranean and North Atlantic, 1989 and 1990. Earlier necropsies reportedly attributed the deaths of a sperm whale in the Lavezzi Islands, between Corsica and Sardinia, and another examined in Iceland to gut blockages caused by plastic bags and sheeting.

More recent cases have kept the issue in the news, including a sperm whale found off Sardinia in 2019 with around 22 kilograms of plastic inside it.

Graphic photo: tap or click to view

A widely shared composite: above, a dead sperm whale on a beach; below, researchers spreading out plastic recovered from a whale's stomach. The lower photo carries the watermark of Greece's Pelagos Cetacean Research Institute; the "100 plastic bags" figure in the caption is the meme's own and is not independently confirmed.

Why deep divers mistake plastic for squid

Sperm whales and beaked whales are both deep-diving hunters that feed mainly on squid. A drifting plastic bag or a loose length of sheeting, rippling in the current, has roughly the size, softness and movement of their prey. Sea turtles face the same trap with bags that resemble jellyfish.

Beaked whales have suffered badly. A juvenile female Gervais' beaked whale found in Puerto Rico in 2011 reportedly carried several kilograms of plastic, and a Cuvier's beaked whale that died at Rarotonga in the Cook Islands in 2006 was reported to have swallowed a single plastic bag. In March 2019 a Cuvier's beaked whale that washed up in the Philippines held around 40 kilograms of plastic.

A necropsy team at work on a dead whale on a shingle beach. Examinations like this are how researchers document what a whale swallowed and whether it played a part in its death.

Baleen whales: swallowing debris by the mouthful

Baleen whales feed differently. Instead of hunting single prey, they gulp enormous volumes of water and strain out krill or small fish, and any debris in that water comes in too. In 2000 a Bryde's whale stranded near Cairns, Australia, was reported to have its stomach tightly packed with several square metres of plastic, including supermarket bags and food wrappers.

The case that gave this story its original headline came from the United States. In April 2010 a gray whale died after stranding on a beach in West Seattle. Its stomach reportedly contained more than 20 plastic bags, small towels, surgical gloves, duct tape, a pair of sweatpants and a golf ball, alongside other rubbish. Whether the rubbish actually caused its death was reportedly never established, which is an important nuance: plastic does not always kill quickly, and a stranded whale may have several problems at once.

How plastic harms a whale from the inside

Plastic passes through a whale's stomachs largely unchanged. Small amounts may move through the gut, but sheets, nets and bundles of bags can lodge in the stomach chambers or intestine. The effects range from a sudden fatal blockage or rupture to a slow decline: a stomach full of material that cannot be digested leaves less room for food, so the animal may starve while feeling full. Sharp fragments can cause wounds and infection, and weakened animals are more likely to strand.

The scale is hard to pin down. A figure often repeated online says plastic kills one million seabirds and 100,000 marine mammals a year, but its origin and method are unclear, so it is best treated as a rough estimate. Firmer numbers exist for the problem itself: a 2021 review in Science counted 1,288 marine species known to ingest plastic, and recent estimates suggest that around 19 to 23 million tonnes of plastic leak into rivers, lakes and seas every year.

Seabirds share the same fate

Whales are the largest victims, but not the most numerous. On Midway Atoll in the North Pacific, home to a huge Laysan albatross colony, parents skim the ocean surface for food and bring back bottle caps, lighters and fragments along with squid. From 2009 the photographer Chris Jordan drew global attention to the colony with images of chicks whose decomposed bodies revealed stomachs full of plastic. Studies there suggest that nearly all chicks carry some plastic and that it contributes to deaths through starvation, dehydration and injury.

(The video originally embedded here is no longer available on YouTube.)

What actually helps

Much of the plastic found in whales is not from beach picnics but from industry and fishing: greenhouse film, nets, rope and packaging. That means change has to happen at several levels.

• Use less single-use plastic. Reusable bags, bottles and cups, and skipping balloons at outdoor events, cut the everyday flow.
• Bin and recycle properly. Much ocean plastic starts as litter or poorly managed waste on land, carried down rivers.
• Support better rules. Bag charges, deposit-return schemes and controls on agricultural plastic have measurably reduced litter where they are enforced.
• Back gear recovery. Programmes that collect old fishing nets and lost gear remove some of the deadliest debris from the water.
• Report strandings. Every necropsy adds to the evidence that shapes policy.

The Terschelling whale could not be saved. What it carried in its stomach, though, became part of a growing scientific record that has helped move plastic pollution from a niche worry to a global priority.

Sources: Originally compiled by Live Free Live Natural from Sea Shepherd Netherlands and InvestigateWest material. Further reading: Mongabay: the Granada sperm whale study (2013); Wikipedia: Marine plastic pollution.

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