A little piece of plastic is all it takes to destroy an animal’s life.
Last Friday, a dead harp seal pup was found on the island of Skye and brought to the Scottish Marine Animal Stranding Scheme, a government-funded organization that investigates mortality in marine mammals. There, veterinary pathologist Andrew Brownlow necropsied the corpse and pulled a small, crucially placed square of plastic out of its stomach. He posted about the case on the SMASS Facebook page on Wednesday.
The animal was likely eight months to a year old. Brownlow says it’s unusual to find plastic debris inside a seal stomach—seals more often become entangled by fishing nets, lines, and lures and die that way, rather than being killed by small floating plastic debris.
“Plastic ingestion in cetaceans and seals is really rare,” says Brownlow, who also heads SMASS. “They’re intelligent animals that seem to be able to distinguish between plastic and prey.”
The incident highlights just how pervasive plastic pollution is—even the smartest marine animals are falling prey to the deadly epidemic.
Normally, SMASS gets reports of stranded gray seals and harbor seals, which are common in Scotland. But finding a harp seal, which generally live in the Arctic, was unusual.
“This did not look like a gray seal,” Brownlow says. “[With a necropsy,] we don’t just tell how an animal died but we also try and understand how it lived.”
Harp seals are not endangered. They spend most of their time swimming the icy waters of the North Atlantic and Arctic oceans, feeding on fish and crustaceans, and they migrate to their breeding grounds in Newfoundland, the Greenland Sea, and the White Sea each year. (Related: “How a Wayward Antarctic Seal Ended Up on a Brazilian Beach”)
Finding a harp seal as far south as Scotland is rare, Brownlow says, but not impossible. He suspects the pup could have been born in northern Norway and, for some unknown reason, headed south. The animal could have been following prey or other seals, or it could have been lost, he says. In the Facebook post, Brownlow wrote that climate change may have also played a role in the animal’s displacement. (Related: “Baby Harp Seals Being Drowned, Crushed Amid Melting Ice”)
During the necropsy, Brownlow and his team of scientists found a flimsy 2-inch square of plastic crumpled up in the harp seals’ stomach. Mild ulcerations indicated that the plastic had been stuck there for some time. The debris could have blocked the pyloric sphincter, the part of the stomach that empties into the intestines, and prevented the animal’s stomach from emptying. The intestine was also inflamed.
Brownlow is quick to add that the plastic did not directly kill this seal. The animal was autolyzed, dehydrated, and emaciated, showing it had already been sick and hadn’t eaten recently before its death. The corpse had evidence of sepsis and some parasites, but no trauma.
Musk oxen put up a defensive ring around their young in Alaska's Arctic National Wildlife Refuge.
Brownlow says it’s likely that the plastic piece damaged the tissue of the stomach and allowed bacteria from the gut to flow into the bloodstream. The pup would have died early anyway, but the plastic piece could have sped up the process.
Plastic can’t be broken down in the stomach, but if the animal had been healthy, it might still be alive. The animal probably would have been discomforted, but the film most likely would not have killed it.
“This isn’t a problem from a conservation point of view, [but] it is pretty much a tragedy from an individual point of view,” Brownlow says. “[Plastic pollution] is the last straw that breaks the animal’s back.”
The Trash Crisis
Harp seals aren’t the only species plagued by plastic. Curious sea lions and other seal species often become entangled in ocean debris like fishing equipment, as well as plastic bags and packing bands.
About 700 species eat plastic, often thinking it’s food. But instead of providing nourishment, the debris can puncture the lining of the stomach, leading to starvation and death. Endangered sea turtles and seabirds ingest the waste, and fish, whales, and other gilled marine animals are increasingly at risk of consuming microscopic plastic debris. (Related: “Plastic Bag Found at the Bottom of World’s Deepest Ocean Trench”)
Since humans eat fish, we could be inadvertently looping ourselves into the plastic-eating food chain as we ingest microfiber bits of straws, bottle caps, and plastic wrappers.
Some plastic pollution is visible, but more than 90 percent of all plastic litter is less than half an inch long. At this size, the pieces might not be detectable to the public eye, but they can still mean a death sentence for unknowing animals.
“This is why these tiny little [plastic] pieces are as significant as the floating islands of this stuff,” Brownlow says. “Even little bits of plastic are the problem.”