[Clip of Greenpeace Activist] This is a 600-foot floating slaughterhouse capable of processing an entire whale in less than half an hour.

Tulika Bose: In June of 1975, several GreenPeace activists set sail under a banner which would become a famous slogan. 

[Clip of Greenpeace Activist] We were left with no alternative but to carry out our pledge  to use our bodies as shields.

Bose: Save the Whales. 

[Clip of Greenpeace Activist] We stopped one chaser boat already and saved one plot of whales. Not bad for a morning’s work. 

Bose: Greenpeace’s constant campaigning against commercial whaling worked. 

Bose: The international whaling commission issued a moratorium on whale hunting in 1985. Humpback whales — a population once decimated by more than 95% — started making a comeback. 

[Whale Sounds]

Bose: But — something’s recently happened. 

[NEWS CLIP] Concern at the Jersey Shore after yet another whale washed up on an Atlantic City beach.

Bose: Dead whales have started washing up on shores again — many over the last winter.  

[NEWS CLIP] More whales are washing up on the East Coast this weekend and now marine conservation groups are trying to figure out why it’s happening.

Bose: It all begs the question — do we need to save the whales again? 

Bose: For Scientific American’s Science, Quickly — I’m Tulika Bose. 

[Bumper]

Joy Reidenberg: What's happening right now is what's called an unusual mortality event. That is the official name for an unusual number of dead animals washing up of a particular species.

Bose: That’s Joy Reidenberg. She’s a comparative anatomist and a scientist that also does whale necropsies — or in layman’s terms, whale autopsies.

Reidenberg: So when an animal washes ashore dead, the first thing we do is we examine the outside of the body. Why did the animal die, and what can we learn from its body? 

Bose: Though scientists can’t confirm what’s causing this unusual mortality event — there’s something that Joy can tell us about the dead whales. 

Reidenberg: Many of them seem to have some kind of indication that they’ve been killed through an interaction with humans. And that interaction is actually mostly ship strikes. 

Bose: And to really verify what’s killed the whale, Joy and a team have to dig inside the body of the whale itself.

Reidenberg: What we look for is, is there any evidence that there was bleeding at the site of the injury. 

Bose: This by the way — isn’t easy.  A fully grown humpback whale, for example, can weigh up to 80,000 pounds and be as long as a schoolbus. 

Reidenberg: So when the whale is in the path of a ship, it can actually bend the whale completely in half and break its spine, it can crush its ribcage and crush the vital organs inside, and then it can have slices through its body and those slices can be fatal if they slice through deep enough. 

Bose: But ship strikes don’t always tell the whole story. 

Reidenberg: If we look at the tissues and we don’t see evidence of bleeding, or bruising which is of course caused by blood vessels rupturing and causing this bloody stain inside the tissue, then the animal was hit after it was already dead — because a dead animal doesn’t bleed. It could be that the animal was already dead and it just got run over by a ship. In which case those slice marks might have not happened to a live animal. 

Bose: And that’s because there are also other human interactions with whales that kill them besides ship strikes alone. 

Reidenberg: Such as they could get tangled up in fishing gear. They often can't swim very well, they can't feed very well, especially if the lines wrap around the mouth, and the animal could actually die of starvation.

Bose: Not to mention — whales also get sick from viruses and bacterial infections. 

Reidenberg: So — sometimes figuring out what the cause of death is can be extremely hard. 

Bose: But — there’s something that Joy wants to clarify, as a scientist. Wind farms have been getting a lot of attention lately for allegedly playing a role in the recent spate of whale deaths. 

[NEWS CLIP] Too many dead whales are washing ashore, and that has activists calling on President Biden to offshore — to do something about offshore wind energy activity. 

Reidenberg: That’s because things that generate sound in the water can interfere with a whale’s ability to hear and can even affect their ability to communicate with other whales. 

Bose: However — Joy says that something doesn’t add up. 

Reidenberg: Right now there is no data to support that the wind farm industries, whether it's the wind farms themselves, or the seismic surveys that are done to determine where to place a wind farm have any effect on these whales. 

Bose: Here’s why. 

Reidenberg: Those sounds are not in the frequency range that these whales hear. So it's unlikely that that's causing their deafness. 

Bose: In fact  — Joy has another explanation for what could be causing the sudden increase in whale deaths. It’s not what you might think.

Reidenberg: What's probably the leading reason for the unusual mortality event is that we've done such a good job conserving these whales that their population has grown. So having such a large number of whales in the area means that if a certain proportion of a population is going to die anyway from natural causes, that number is going to be an absolutely higher number if your population is bigger. 

Bose: Joy has even more guesses as to why so many whales could be dying. 

Reidenberg: Are the whales staying in our area longer than they should be? Is something happening with their migrations? Something related to climate change? Is it related to the fact that whales are feeding in areas that are shipping lanes and now there are just more of them, so they’re getting hit by the ships? 

Bose: It’s important to note that online shopping during the Covid Pandemic led to record-making increases in cargo shipments along the East Coast last year, which is where and when a lot of the whales stranded. And — there are a lot of injured whales swimming around that have had contact with ships. 

Reidenberg: There are many whales still swimming around today that have slice marks on them from encounters with propellers. Damage that is significant, but it's not lethal. So for example, lopping off a tail is pretty significant damage, but it won't kill the whale. 

Bose: By the way, data on this is being collected and tracked at the National Marine Fisheries service. And — it might just mean we need to save the whales again. 

Bose: Thanks for listening. For Science Quickly, I’m Tulika Bose. 

Science Quickly is produced by me, Tulika Bose, Kelso Harper, Jeff Delviscio. 

Music by Dominic Smith. 

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You can also check out ScientificAmerican.com for updated and in-depth science news. 

See you next time.

[The above is a transcript of this podcast.]