Science Friday - Why Eels Are So Mysterious—And In Demand

Episode Date: September 4, 2024

Eels have fascinated humans for thousands of years, even captivating big thinkers like Aristotle and Freud. Despite having been around for some 200 million years, eels are still rather mysterious creatures. For example, scientists still aren’t sure exactly how they spawn.But those unanswered questions haven’t stopped humans from wanting to eat them. So much so that they’re now endangered in some areas—and a lucrative criminal enterprise has risen up to poach baby eels from the wild.Guest host Rachel Feltman talks with Ellen Ruppel Shell, author of Slippery Beast: A True Crime History, with Eels about her journey into the wild world of eels.Read an excerpt of Slippery Beast: A True Crime History, with Eels. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

Eels have fascinated humans for thousands of years, captivating big thinkers like Aristotle and Freud, and they still make their way into pop culture every now and again. Electric eels are not actually eels, but I digress. It's Wednesday, September 4th, and you're listening to Science Friday. I'm sci-fi producer Shoshana Bucksbaum. Despite existing on planet Earth for some 200 million years, eels are still rather mysterious creatures. For instance, scientists still aren't sure exactly how they spawn.

But all of those unanswered questions haven't stopped humans from wanting to eat them. And a lucrative criminal underworld has risen up to poach baby eels from the wild for exactly that purpose. Here's guest host Rachel Feltman with more. Joining me now to talk all about her journey into the wild world of eels is my guest. Ellen Rupilchell, author of Slippery Beast, a true crime history, with eels. She splits her time between Bremen, Maine and Somerville, Massachusetts. Ellen, welcome to Science Friday. It's great to be here. Thanks so much, Rachel. Thanks so much for coming on. So I'll start with the most obvious question to ask someone who wrote a book all about eels,

which is, why eels? Well, that's a simple question and a complicated question. So the short answer is I didn't find eels. Eels found me. Would you like to know the story behind that? I would love to know the story behind that. Okay. Well, quite a few years ago, as you mentioned, spend about half the year on the coast of Maine.

And one year, my husband and I decided we needed some help with home repairs. So we hired a guy who in the book I call Sam. Sometimes he come in quite early, come to my kitchen with a four-pack of cider and just want to talk. And he'd tell me stories about his family and especially about his grandson, who he said he wanted to teach to fish as soon as he got the money together to buy a boat. And I said, well, Sam, why don't you mix business and pleasure and buy yourself a commercial fishing license to go with that boat? And he said, well, I did do that and I would do that, but, you know, the eels. And I said, what? What are you talking about? The eels? You afraid they're going to bite you or what? And he said,

no, I'm not talking about eels big enough to bite you. I'm talking about the little eels, you know, the ones the size of your pinky finger, you know, the ones we call the glass eels or the elvers, the baby eels. Ever since the price of those eels went through the roof, it's been dangerous down by the river. And I said, what do you mean the price went through the roof? And, and I said, what do you mean the price went through the roof. And he said, whoa, you know, they're about $2,500 a pound. Well, as you can imagine, that got me curious about the eel. And, you know, Sam left. Years went by. I couldn't get the eel out of my mind. And I started looking into it. And I found not only where the price was the price through the roof, but the eel was a most remarkable animal, and the natural history of

this animal kind of paralleled the history of science. And I got pulled into this story, as do so many people who encounter the eel, and it just wouldn't let go. Yeah. Well, there are so many absolutely fascinating eel facts in your book, but let's start with some very basic stuff. Can you give us a quick overview of the eel life cycle and why it confused scientists for so long? Yeah, eel is such mysterious animal. No one knew how it reproduced. So Aristotle, you know, about 2,000 years ago, he started things going with this idea that eels reproduced by spontaneous generation. Okay. And he held us theory as did people for, you know, almost 2,000 years, this idea that eels just reproduced out of the mud. They did not sexually reproduce, but they reproduced out of the mud. And the reason for that is because eels were everywhere and no one had ever seen an eel mating. No one ever seen an eel egg. No one had ever seen a pregnant eel.

So, yeah, how and where eels breed has, of course, long been a mystery to scientists. Remind me, what do we know and not know about where they spawn? Okay. Well, it is thought today that the Atlantic eel, that is the European eel and the American eel, both spawn in the sarcant. Sarasso Sea south of Bermuda. Again, it is thought no one has ever spotted a mature, sexually mature eel in the ocean or a mature eel in the ocean. And no one has ever spotted an eel egg in the wild.

Okay? So we're not absolutely sure of this, but it is thought that they spawned in the Sargasso sea. In the case of the American eel, which is the eels we were talking about in Maine, it spawned in the Sargasso Sea. and then it grows into a larval stage. And that larva, which is maybe three to five inches long, travels all the way from the Sagaso Sea up through the eastern seaboard,

in the case of the main eels, up to the main coast. And as it crosses toward the coast, it becomes what we call a glacial. They look like little transparent toothpicks. And then as it comes, it tends to come into the freshwater, area as it starts to do that, it becomes an elver, it becomes pigmented. And some, some eels stay in the ocean and some continue up the rivers and settle down into lakes or other places, other waterways, where it just eats. It becomes a yellow eel, and it just eats and eats and grows and grows,

and it can stay there for as long as up to 40 years. And then after it reaches a certain point, Somehow it knows to return to its spawning place in the Sagaso Sea. It becomes what we call a silver eel. That's the last stage in this development. And it retraces its steps all the way back to a spawning ground where it spawns once or maybe twice, we're not sure, and then dies. And that's the life cycle of the eel. So you can imagine how typical it was for ancient scholars to have any idea of how the eel reproduced.

Wow, yeah. And as you were just describing, you know, eels have to migrate thousands of miles. Do we know how they do that navigation? Oh, wow. Well, that was such a controversial question. I mean, some folks thought, some scientists thought it was olifaction because eels have an incredible sense of smell. Some felt that they were following the gravitational forces from the moon. There were all different theories. Most recently, it's been thought that they have a magnetic sense. sense, that they have particles around their nose area, the front of their face, that are magnetically sensitive, and that they're drawn by the magnetic fields toward their destination, right? This, again, is controversial. I went to Norway to discuss this with a scientist who was most closely associated with this theory. Her name is Carolyn Duraff. She's an amazing scientist, and she has a laboratory there where she did the experiments that resulted in this conclusion. It seems to be probably the most likely theory. They have a certain magnetic sense, eels do, that draws them to their destinations in both directions,

both from the sagasso Sea and back to the sagasso Sea. So personally, I had the pleasure-dubious honor of helping to catch some wild eels for research back when I was an undergrad. But I think most folks these days have their first eel encounter when they see, you know, maybe Unagi at a Japanese restaurant or maybe at like the Feast of the Seven Fishes, if you have a particularly ambitious Italian grandma. But like other types of seafood, they've been overfished. So what are the statuses of the three populations of eels, the American, European, and Japanese eel? Well, exactly. So there are about 820 different species of eels. And the ones that we think about, the freshwater eels, there are maybe 18 different species. And the most commercially viable ones are the Japanese eel, the American eel, and the European eel. Now, all those eels have declined in number dramatically since the 1970s. It's thought that the Japanese eel is declined by as much as 95 percent, the European eel by as much as 95 percent. and the American eel by about 50%. So as you can see, the Japanese and European eel are both critically endangered. The American eel is not classified as critically endangered,

but many scientists believe that it's on the verge of becoming quite endangered. It's certainly under threat. Yeah. Even going into your book as something of an eel enthusiast, one thing that really blew my mind was your deep dive into the international wild eel trade. So how is it that baby eels or elvers from Maine end up on eel farms in China? Yes. So there's an elver season. So elvers are baby eels. There are about 2,500 of these eels to a pound to give you some idea of how small they are. These eels are caught in the estuaries generally or in the rivers of Maine in the case of the Maine eel.

The only legal place to catch elvers in the United States is the state of the state of. of Maine. There's a very small fishery in South Carolina, but it's really not significant. So the only significant elver fishery in the United States is the state of Maine. So they're caught on the coast during elver season, which starts in March and usually ends in June. And then they are shipped, by and large, they are shipped to farms in Asia, generally China, to be grown up to market size. It takes six months to a year to grow them to market size, after which they are slaughtered and prepared and sent back to the United States for sale. So it has the supply chain for the American eel in the United States is circuitous and dramatic, really, as the life cycle chain

of the American eel. And in that process, as you can imagine, there's lots of room for slippage, poachers, all sorts of things. International cartels are involved in this. Criminal cartels, organized crime. It is the most costly wildlife crime on the planet. It's hard to imagine this, that elvers, not tiger paws, not ivory from elephants, elvers are the world's costliest wildlife crime. Wow. And can you say a little bit more about what it is about the eel industry, and the supply chain that lend itself to criminal enterprises? Really, what it comes down to is money. Our other big product in Maine, of course, is lobster.

Elvers are about 400 times the value of lobster. It's very, very valuable and quite relatively easy to ship and smuggle. And so unlike, you know, an elephant, elvers are very, very small. So that has really brought in all sorts of, you know, criminal elements into this industry. It's, as everyone told me, you know, eels are a dirty business, always have been. But since the price went through the roof, it's gotten very dangerous as well as dirty. Hmm. And speaking of eel crime, you interviewed a kind of notorious eel kingpin named Bill Sheldon for the book. Can you tell me more about Operation Broken Glass? Bill Sheldon is such an

interesting guy. He's literally an expert on the eel, on the American eel. He has a degree in wildlife management. He's also a grandfather. He's not a young man. And Bill was the biggest eel dealer in the state of Maine. And unfortunately, as Bill himself will admit, he got greedy and he got involved in a coaching ring that involved six states up and down the East Coast that encouraged the illegal fishing of eels, elvers. And let's make sure we understand this. It's the baby eels that we're interested in.

illegal fishing in states, you know, where it was not illegal to fish, alvers. And the alvers were then laundered through the state of Maine with Bill's help. And this operation broken glass was a four-year federal investigation that ended in April of 2014 with the arrest of about 110 criminals up and down the East Coast. 22 people were imprisoned, including Bill Sheldon, who I interviewed about a month and a half after he got out of the state penitentiary. So unfortunately, with prices that high, even people with expertise and long experience of honest fishing of Elvers got pulled into the trap of, you know, illegal activities. But I'm sure some folks are wondering, you know, why don't we just catch and eat adults instead?

But as you share in the book, wild-caught adult eels actually taste pretty best. that. Can you explain why? Yes, well, eels, as I mentioned, can live a very, very long time. The ideal weight for eel, especially in something like sushi, which is what the preparation that Americans prefer, those eels are small, relatively small, and you have to catch them at just the right time to get them that size. That's virtually impossible. You really can't time that in the wild. The other factor is, As I said, they do live a long time and they're bioaccumulators. Eels are very, very fatty and they store all sorts of things in that fat. And many river bottoms where they are nocturnal animals during the day, they burrow in the mud

and absorb all sorts of toxins and unhealthy materials from that riverbed. Not only are you exposed to those toxins, but it doesn't taste very good. So many Americans do not like the taste of wild eel. And I had the opportunity to taste it myself in Norway. I did taste wild eel. I'm a big fan of domesticated eel or cultivated eel. I was really shocked at the taste of wild eel. You know, I sort of describe it as almost like a wet sponge taste.

It's really not something that many of us would really enjoy. Yeah. Now, I've spoken to people who really do like it. You know, there's various countries, you know, certainly have a tradition of eating wild eel. but it really depends very, very much on where you get it, how old it is, all these factors that you really can't control. So cultivated eel is what the vast majority of eel eaten around the world is. It's not wild eel. Right. And given everything you learned about the bad actors in the eel trade and the threats that eels face, should people just avoid eating eel altogether?

You know, that is such an interesting question and a complicated word. And many scientists told me people should not avoid eating eel because if we lose it as a commercial product, we're going to lose interest in it all together. They would prefer that people continue to eat eel in moderation, but kind of know where it comes from and be mindful of where it comes from, just like so many things we think about eating, right? If we can do that, if we can balance our concerns, our environmental concerns with our hunger for eel, we'll be better off than if we just simply stop eating it. Ellen, thank you so much for joining us today. Thank you very much, Rachel. Ellen Rupel-Shell is the author of Slippery Beast, a true crime history with eels. She splits her time between Bremen, Maine, and Somerville, Massachusetts.

If you want to read an excerpt of the book, go to ScienceFriiday.com slash eels. That's ScienceFriday.com slash eel. That's just about all the time we have for today. Lots of folks help make the show happen, including... Dee Petersman. Sandy Roberts. F. Ramby. John Dancosky.

Tomorrow, dogs who are trained to sniff out spot-urn lantern flies, plus new research about the origins of the asteroid that killed the dinosaurs. I'm SciFRI producer Shoshana Bucksbaum. Catch you next time.