Dolphins Are Dying and No One Knows Why

If an Unusual Mortality Event sounds like something out of a movie, it’s not. There’s one happening right now.

Unusual Mortality Event sounds like something out of a Roland Emmerich movie. A downtrodden, bespectacled scientist discovers it after an alarm beeps in the dank dungeon lair that doubles as his office. As he attempts to discern the cause of the noise, he knocks over a wobbly stack of papers, piled high because he has neither the time nor the will to file them. He locates the alarm, realizing the severity of the Unusual Mortality Event, only to be interrupted by a phone call. It’s his ex-wife. “[Generic sounding scientist name], you forgot about [Sam/Ben/Dana]” she says, wearily. “You remember, our child….” He cuts her off. “I have to go, honey,” he says, that last word indicating that he still pines for her and maybe, just maybe there’s a chance to redeem their relationship. “We’re facing an unprecedented Unusual Mortality Event,” he continues dramatically, both for her benefit and, conveniently, for the benefit of the viewing audience that’s beginning to wonder whether it was worth paying an extra five dollars to see this film in the RPX theater, especially since there has been far more family drama than stuff blowing up, which is why they shelled out more money in the first place.

At this point, our heroic but overlooked scientist brings his concerns about the Unusual Mortality Event—now shortened to “UME” because this thing has a run time of 99 minutes, tops, and there’s a huge special-effects budget left to blow through—to a mid-level official in the executive branch. His pleas are ignored at first but eventually accepted. Things die. Sam/Ben/Dana is in grave peril, then suddenly saved. The future of humanity goes right to the brink before getting pulled back. We all live happily ever after.

Except Unusual Mortality Events—which are unexpected, involve significant deaths, and require immediate action—don’t come from movies. They are real. Very real. And one of them is taking place with tragic results in the Atlantic Ocean right now.

IN JULY, BOTTLENOSE DOLPHINS started washing up dead on the shores of New Jersey beaches. This continued throughout the late summer, fall, and winter—the only change being that the location of the mammal carcasses shifted south to Florida as the ocean warmed. Between July 1 and December 15, 996 dolphins were “stranded,” which is marine-biology speak for a much darker reality. Compare that figure to the 117 average during the same period between 2007 and 2012, and, well, we have an Unusual Mortality Event that continues today.

This isn’t the first one. Between June 1987 and May of 1988, more than 700 bottlenose dolphins died in the Mid-Atlantic. It’s estimated that the figure represented roughly half of the Mid-Atlantic population. When it was discovered, no one knew the cause. But marine biologists kept samples of tissue from the deceased animals and later discovered that cetacean morbillivirus killed the dolphins. The disease, which is in the same genus as measles, only affects dolphins, whales, and porpoises.

While humans cannot contract morbillivirus, the plight of the dolphins might signify a concern about the health of the oceans.

Morbillivirus is also to blame for the recent deaths. It’s one of the first things scientists test for now that they know it exists. (A 1990 die off and another in 1994 in the Gulf of Mexico have been attributed to morbillivirus, too.) In August, biologists determined that morbillivirus was the cause of the latest Mid-Atlantic UME.

What no one knows: why now? Morbillivirus is endemic to the dolphin environment. It’s always floating around, waiting to be passed through the air via exhalation from a dolphin’s blowhole. So why are they dying off in 2013?

One theory, according to Erin Fougeres, a marine biologist with NOAA Fisheries, is that outbreaks are cyclical. “Those bottlenose dolphins that don’t die develop natural antibodies,” she told me over the phone. “As those animals slowly die out of the population, herd immunity drops which can lead to an outbreak. That’s what we think it’s happening.” Essentially, the dolphins that survived in the late 1980s were immune, but there are enough younger, non-immune dolphins today to spark an epidemic.

The other theory is scarier: that we’ve done something terrible to the ocean and the die-off is the first sign of something larger. “Marine mammals are very good sentinels for ocean and human health, and they really act like the proverbial canaries in a coal mine,” Dr. Greg Bossart, a veterinary pathologist and senior vice president in charge of animal health at the Georgia Aquarium, told The New York Times in December. “They give us an idea of what’s occurring in the environment.”

I asked Fougeres if she agreed with the canary-in-a-coal mine metaphor when it came to the bottlenose dolphins. She said she did. While humans cannot contract morbillivirus, the plight of the dolphins might signify a concern about the health of the oceans.

“We will continue to look and see if there are any underlying causes that might make them more susceptible to the virus this year versus other years,” she said. “Something like global warming might make a species interact with another one this year. These are theories.”

We’ll have a better idea in the spring. So far, the outbreak is following the same pattern it did in 1987 and 1988: start up north, then move south. Fougeres and the NOAA team believe the location where they find stranded dolphins will begin moving back up north after the winter. The die-off should stop in May. That’s the hope, at least.

But no one knows. There was an unrelated UME in Louisiana’s Barataria Bay, an area affected by the BP Deepwater Horizon oil spill. All the deaths aren’t linked but, as the NOAA marine biologist told the Times, “it says there are a lot of challenges that marine mammals are facing.”

While none of this sounds good, it—admittedly—would make a rather dull action movie. But it might make a good horror flick.

Related Posts