This is a transcript of the Gastropod episode Oysters: History and Science on the Half-Shell, first released on October 18, 2016. It is provided as a courtesy and may contain errors.

ROWAN JACOBSEN: My name is Rowan Jacobsen and my book is The Essential Oyster.

CYNTHIA GRABER: And so this is your second book on oysters. How did you get so excited about them?

JACOBSEN: Yeah actually, technically it’s my third book on oysters which is kind of embarrassing. This is definitely going to be my last book on oysters, I can tell you that.

NICOLA TWILLEY: Rowan Jacobsen’s middle oyster book is about the intertidal zone where oysters live, not oysters specifically, so I forgive Cynthia for not knowing that. Cynthia is usually very good at research.

GRABER: Thanks. I was a little concerned when he said that. But Rowan is in fact an oyster expert. His first book on the topic was The Geography of Oysters. Now he has a gorgeous new book out called The Essential Oyster. My partner Tim called it oyster porn.

TWILLEY: And anyone who knows us knows we love us some oyster porn. But if you don’t know us, we should we say: you’re listening to Gastropod, the podcast that looks at food through the lens of science and history. I’m Nicola Twilley.

GRABER: And I’m Cynthia Graber. And this week, Rowan will take us on a tasting tour around the world. We’ll get into the science of oyster flavor and oyster biology, and the history of oyster cultivation.

(PRE-ROLL)

(MUSIC UP)

JACOBSEN: Can we start with the shucking of the oyster? Because to me that’s part of the whole gestalt.

GRABER: Great.

TWILLEY: Yes.

JACOBSEN: So you’ve got this shellfish enclosed in its shell. So your first step is to get it open and you know it’s a little bit of a battle usually but you almost always win, which is kind of nice. It’s good to start with a little victory. And then you open up this, you know, this creature, denizen of the sea. And you immediately release, you know, the smell is just like that classic tide pool smell, so to me it’s very transporting because you’re immediately just right there on the rocky coast somewhere or on the beach. Then you pop it in your mouth and for some people that is the first challenge because an oyster is a lot squishier than most food we tend to eat, so there’s a bit of a slime factor.  But once you’ve eaten enough oysters that’s actually a plus, because you’re anticipating it and it’s just part of that, you know, that primal tidepool experience. Then you usually get a wave of salt, and it depends on the oyster because some oysters are a lot saltier than others, but you get this wonderful hit of salt. But then after then you know you kind of give the oyster a few half-hearted chews, and as you do that there’s this little hint of sweetness that follows up after the salt. And then after you’ve swallowed the oyster then you get, you sort of get this lingering, like these weird little just like pulses of flavor on the finish that can be all over the place.

GRABER: I’m hungry now just listening to that description.

TWILLEY: You’re always hungry during our episodes

GRABER: Nicky, you know, I’ve eaten so many of them—and I still don’t really get just what it is when I’m looking at it. It’s not like a leg of chicken—you know exactly what you’re eating. But what is an oyster?

JACOBSEN: All right so it’s—an oyster is a bivalve, meaning it has two shells like a clam or a mussel, and it’s a filter feeder like all other shellfish. So what—what it’s doing all day and all year long is it’s attached to a rock or another shell. And when it’s covered with water all day long, its shell is cracked open and it has these gills and it’s just pumping water across its gills and filtering out the phytoplankton, the little single-celled plants. And that’s what it eats, they just filter algae all day long and feed the algae and convert it into flesh.

TWILLEY: But what are we actually eating? What is that blob? I mean, are we eating its brains?

JACOBSEN: You’re not eating brain because they don’t have one. They’re super simple. You’re definitely eating belly and muscle and gills and cilia and the whole—the whole digestive tract and there is a little heart. Like if you look in an oyster, the plump end of it is the belly. And then in sort of in the center, you’ll see a little round disc that’s kind of ivory colored, looks kind of like a scallop muscle and it’s the exact same thing as a scallop has. That’s the little muscle it uses for opening and closing its shell. That’s another thing that I think—it kind of puts oysters in a different category—is we’re eating an entire animal and that’s pretty rare these days for most of us. It’s kind of interesting, the mix of flavors and textures with an oyster is all because of the different anatomy. The belly is really soft and it kind of pops almost like a soft-boiled egg when you bite into it and it tends to be salty inside, and the muscle is chewier and has the sweetness to it. So you mix those two together and you get sort of the full oyster experience.

GRABER: It turns out that you can even see the heart beating.

JACOBSEN:  All oysters have kind of a flat side and a curved side. If you shuck the curved side with a really sharp knife, really carefully so you haven’t cut into the body of the oyster at all, you’ll see that disc of muscle that you just cut free. And sort of like nestled into one side of that muscle, you’ll see a little tiny kind of oval shaped more translucent—what looks like part of the muscle but that’s actually the heart and it’s almost got a little bit of a drum curve to it and you’ll see it pulsing if you’ve done your job really well.

TWILLEY: Hmm. That’s a little freaky. I don’t know if I want to see my oyster’s beating heart before I slurp it. It feels a little Hannibal Lecter.

GRABER: If you miss the beating you wouldn’t know it’s a heart, though—the blood is entirely transparent.

TWILLEY: That’s even more freaky, to be honest.

JACOBSEN: Basically seawater is what an oyster uses as its—for its circulatory system, for its blood. So whatever the salt level is in the water it’s in, it’s going to be the same as the saltiness of the oyster. And so, like, I can eat an oyster blind and tell right away whether it came from an area that was exposed to the ocean, so it’s going to have an oceanic level of salinity, or whether that oyster came upriver from brackish waters where a lot of fresh water was mixing. Like somewhere like the Chesapeake, the salt’s going to be hardly detectable.

TWILLEY: Okay, so some oysters are just lightly salted, and some are a salt explosion in your mouth, depending on the saltiness of the water they grew up in. But that’s not the only way that oysters can taste different.

JACOBSEN: There’s hundreds or thousands of different species of plankton that oysters are feeding on. And so just like you know depending on what you feed a pig, it’s going to influence the flavor of the meat. The oysters are just usually just like little pigs. So one thing I’ve noticed is oysters that grow near salt marshes tend to get that grassy olive taste, it’s like an astringency that you get with olive oil. And another thing that is really—there’s a little bit of science on it but it’s—we used to think oysters really just eat plankton from salt water. But it’s turning out that they, especially in times of year when there isn’t that much plankton in the water, they’ll actually feed on a lot of, you know, vegetal material that’s washing downstream in rivers.  So, and you can taste that. It’s a much less marine flavor and a much more sort of lettuce or chard, kind of cooked greens flavor that you get from these uplands.

GRABER: There are even more factors that influence what your oyster tastes like. It’s just not what the bivalve has been drinking and eating, it’s also the time of year.

JACOBSEN: Oysters have sort of this natural seasonal cycle where when water temperatures are really cold they hibernate, they can’t really process their food anymore. So say like in the Northeast around November when the water temperature drops to 40 or so they’ll just shut down like a bear. We’re switching from pig metaphor to bear metaphor now. And they’ll just hibernate until say, April, when water temperatures warm up.

TWILLEY: And, just like a bear, oysters will fatten themselves up as much as possible to get ready for hibernation

JACOBSEN: So they will gorge through September, October, November and get really fat and really sweet. That’s when you really get that amazing hint of sweetness. And it’s because a) because they’re just so full of food. But also b) I think probably as a defense against really cold temperatures, just like other animals and plants, they’ll develop some natural antifreeze in their body and those tend to be sugary. So in so in that November-December time period it’s going to be just sweet and wonderful. That’s that’s the peak for a lot of oysters. Then through the winter that will hold. It will be—it’ll still be firm and sweet. And then as spring hits, then you’ll get more of those grassy flavors as it starts to feed on some of the new plant sources that are out there. And then as summer hits it starts to think about reproduction. So it diverts all the energy that it was building into its body as food reserves in the fall. Now as it’s eating, it’s putting all this energy into building gamete. And at that stage it tends to taste pretty gamey. So summer oysters definitely are the—tend to be the least tasty of the year because you’re basically eating a lot of sperm and eggs. But then once the oysters have ejected all that into the water column which usually happens in July or August then they’re really skinny and you’ll see it—if you see an oyster that is basically translucent, just looks like a bag of seawater, that’s because it is and it won’t have a whole lot of flavor other than the salt of the sea water. And then it’ll start to rebuild its body through the fall. So yeah there’s three or four different sort of stages of taste.

TWILLEY: So there there is some truth to that old rule about not eating oysters in months that don’t have an R, right?

JACOBSEN: Yes there is. And now the whole oyster industry is mad at me for saying so but… Everyone would like oysters to be a year round product and you can certainly safely eat them year round. But they definitely taste the best in late fall, early winter, and then again in like late spring.

GRABER: This annual flavor variation is slightly different in warmer waters. Oysters from the Gulf of Mexico don’t go through such a dramatic spawning season in the summer and a plumping up time in the fall.

JACOBSEN: So they’re more evened out throughout the year in the Gulf.

TWILLEY: Oysters have been doing their thing on coastlines all around the world for millions and millions of years. They are very ancient indeed. And then when humans showed up, just a few million years ago, we started eating them.

GRABER: Archaeologists think we originally used oyster shells as spoons. And in ancient Greece, voters sometimes voted by making a mark on the inside of an oyster shell.

JACOBSEN: Oysters been popular everywhere they ever showed up. Romans were big into them and just like us they had their oyster appellations. They knew that oysters from certain places were particularly tasty and they imported oysters to Rome from all over Gaul. France has always been a particular oyster hotspot and is to this day.

TWILLEY: The ancient Romans loved their oysters. They shipped them in bathtubs full of ice and served them on the half shell with a sauce made of pepper, lovage, egg yolk, vinegar, olive oil, wine, and their version of fish sauce. Yum?

GRABER: I’m not sure.

TWILLEY: They even baked a special bread to go with their oysters—I guess maybe the original oyster cracker!

GRABER: Native Americans loved their oysters as well. This continent has been home to oysters for millions of years, too. Lots and lots of oysters.

JACOBSEN: You can find middens, which are mounds of old shells, up and down both the East Coast and the West Coast that go back thousands of years. They were definitely a core food for for the Native Americans. And these middens—like you picture like a little shell pile but there they’re like hills. There are entire neighborhoods built on some of these these middens.

GRABER: Those were the hills made of discarded shells—the reefs of living oysters were even bigger.

JACOBSEN: When the first settlers hit the New World they ran aground on oyster reefs. John Smith was stuck on one for a while in Virginia in 1680. He actually camped on it. That’s how big—some of these reefs were 20 miles long.

TWILLEY: Some biologists actually estimate that New York Harbor contained half of all the oysters in the world at one time. Pearl Street, in lower Manhattan, was built on a midden and paved in oyster shells.

GRABER: And there’s a good reason we’ve been eating them for as long as we have. They’re delicious, yes, but they’re also incredibly good for you. They’re a great source of protein. They’re the highest source of zinc you can find in food. They also have an incredibly high amount of vitamin B12 and vitamin C.

TWILLEY: And one oyster can contain as much calcium as a glass of milk. Which is surprising to me. But exciting! More reasons to eat oysters.

GRABER: But all of those oyster lovers of history weren’t enjoying the ones we eat today. They snacked on wild oysters. And you won’t find those on many oyster bar menus these days.

JACOBSEN: There aren’t that many wild oysters left, like you don’t see too many wild ones on the market anymore. Well, you know, it’s kind of funny because like we have this mentality from other foods like fish where we always want the wild ones, right? Like, oh, farmed isn’t as good, you want those wild flavors. But with oysters I’ve found that generally the farmed ones are totally superior in every way to the wild ones. Wild oysters are, you know, it’s kind of like they’ve dropped on to whatever spot they could find. It’s probably not a great spot. They’re probably competing for food with a bunch of other oysters that are packed in with them. So they tend to be long and skinny and you know a little bit emaciated compared to the farmed ones who have it easy so they’re nice and fat.

GRABER: And oysters are not like salmon that have to swim, so it’s not as if they’re missing out on their cardio if they’re farmed rather than wild.

JACOBSEN: Really, they’re still living the same life a wild oyster would lead, except they’ve got lots of space and lots of food and protection from predators. So they tend to just be a lot more plush compared to the skinny wild ones.

TWILLEY: Farming oysters has a long history too.

JACOBSEN: Even in the Roman era actually there were people who were quote unquote farming oysters but it wasn’t like we farm them now.

GRABER: The Romans would first seed oysters in calmer waters so more of them would survive, because the oyster survival rate in the wild is only one in ten thousand. Seeding them in calm waters gave the oysters babies a better chance to grow.

TWILLEY: Then the Romans would take the little baby oysters on twigs and move them to areas with good current and the right salinity to plump up. And they did this kinda-sorta farming method for two reasons. One, they were starting to eat down the stock of wild oysters nearby, and this boosted the harvest. And two, the resulting oysters were fatter. Plusher, as Rowan would say.

GRABER: The Romans weren’t the only ones who started the early oyster semi-farming system. The Greeks did something similar using broken pottery, so did the Mesoamericans. The Japanese moved their oysters with bamboo and leaves. No one knows exactly who invented the technique or when, although some Ancient Chinese sources put oyster cultivation back as far as four thousand years ago.

JACOBSEN: But we didn’t—like the modern style of oyster farming which is really sort of taken oysters to the next level in different ways—it really kicked in when we figured out the whole hatchery concept which was mostly in the 1970s, when that really started.

(MIDROLL)

TWILLEY: So let’s get back oysters. Originally, there were two kinds of wild oysters in North America. The one the New Yorkers were paving their streets with: that’s the Eastern oyster.

JACOBSEN: And it’s native from the Maritime provinces in Canada, all the way down to Florida, and all the way around to the Gulf of Mexico. And so it’s like, it’s always been kind of like the workhorse oyster on the East Coast. And that’s the one that easterners are usually most familiar with. It’s got a very just like a clean briny Atlantic Ocean flavor to it usually.

GRABER: On the West Coast, our second native species is called the Olympia.

JACOBSEN: Really doesn’t get much bigger than a 50 cent piece. And it was always really slow growing, so it was pretty easy to wipe out.

GRABER: And we did wipe them out, almost entirely. The West Coast is one of the most productive oyster regions in the world. But when the Europeans rushed west for gold in San Francisco and then again further north on Vancouver Island, they ate all the oysters. White settlers stole the oyster trade away from Native American women, and then wiped out the local oysters. There are a few left today, but they’re hard to find.

TWILLEY: The same story played out on the East Coast—as New York City got bigger and bigger, its oyster beds got smaller and dirtier. Oysters were being overharvested sure, but it did not help that we were emptying raw sewage into their habitat too. The last wild oyster bed in New York Harbor was closed for harvesting in 1927. But the wild Eastern oyster hung on further south.

JACOBSEN: Louisiana, even after the East Coast had lost all its great wild oyster beds, the Gulf was just such a productive spot for oysters that Louisiana was just still full of millions and millions of wild oysters.

GRABER: Until 2010. That’s when BP’s oil spilled throughout the region. Louisiana lost more than 50% of their wild oyster beds. It was complete devastation.

TWILLEY: So, yeah, today, we mostly eat farmed oysters. Which, like Rowan said, are definitely plusher. More plush? Whatever. And we have more than just two types. In fact, there are five types grown in American waters these days. The Eastern and a few remaining Olympias and three others besides.

JACOBSEN: On the West Coast, the big oyster is called the Pacific oyster and it’s actually native to Japan. And it’s got a much more sort of cucumbery, melony, fishy flavor to it. And it came in in like the 1920s, 1930s after we wiped out the native oyster on the West Coast. Then there’s two kind of wildcards. One is called the Kumamoto, which you’ve probably had. It’s the most popular oyster in the country now probably. Also from Japan originally, smaller and sweeter than the Pacific oyster. And a little harder to grow but can be sold for more money because it’s so popular, and a little bit rarer. So you’re seeing more and more Kumamotos on the West Coast.

GRABER: The fifth oyster is the Belon, which is native to France. It was brought to Maine in the 1940s. But people there couldn’t figure out how to farm it so they just dumped their stock off the coast.

JACOBSEN: And like, 30 years later, these beautiful beds of Belon started showing up off the Maine shore wild. And they’ve since spread down about as far as Cape Cod and they’re all over the place from Cape Cod up to Maine, always lurking in these low water spots.

TWILLEY: Like Rowan says, the Belon is native to Europe. If you’ve ordered oysters in France, you’ve probably eaten Belon.

JACOBSEN: They are super intimidating. They taste—people have described it as coppery but coppery kind of doesn’t really do justice. It’s more like licking a piling, you know, or something. It’s, there’s a touch of creosote and there’s a lot of fish sauce in there. Noisette is the word that the French use to describe the flavor. So there’s definitely a little hazelnut in there too but it’s like hazelnut crossed with fish sauce. It can be really great but it can also be just like really freaky and it leaves, you know, like when you touch your tongue to a battery terminal and you get that little hint of electrical shock?

GRABER: No, actually, I’ve never done that before. But while Rowan’s book focuses on the different oysters you can find all over the US, he also gives a nod to the rest of the world. Because, as we’ve said, oysters grow everywhere, and they’re popular most everywhere.

JACOBSEN: France grows an insane amount of oysters and the average French person eats 18 times as many oysters as the average American. So France is still sort of the center of oyster culture.

GRABER: But France’s Belons don’t corner the market on oysters internationally. The Pacific oyster—the Japanese one that we grow on the west coast—that grows throughout the Pacific. Three-quarters of all the oysters in the world are Pacifics.

TWILLEY: But reading Rowan’s book has made me want to try other species like the New Zealand Flat, which is supposed to be like the Belon, but even more intense. And he describes the Sydney Rock Oysters as the Yukon Gold potato of shellfish—so basically super buttery and creamy.

GRABER: So those are all different oyster species, but then within each species there are also hundreds and hundreds of different varieties.

JACOBSEN: Right, so it’s just like with wines it’s like you know there’s all these different ones that are made out of Chardonnay grapes, but depending on where they grow they’ll be named for the place they grow or be named for the winemaker or whatever. Same thing with oysters. So on the East Coast you’ll have all these different oysters on the market that are all Eastern oysters, but they’ll be named for the place like Wellfleet or Blue point or Apalachicola. Or they’ll be named for the grower.

TWILLEY: And like wine, increasingly growers are giving their oysters completely made up, deliberately catchy brand names, like Naked Cowboy or French Kiss.

JACOBSEN: Yeah, you’ll see 30, 40 different names on a chalkboard menu in a good oyster bar but you’re probably only seeing three different species.

GRABER: And the different varieties all taste different from one another, too. This explosion in oyster flavor and variety is a new phenomenon—Rowan says we’re in the middle of an oyster renaissance. And that’s due to farming, which really didn’t get started until the 1970s, and the invention of the hatchery.

TWILLEY: For thousands of years humans had been cultivating oysters—collecting the larvae from the wild and seeding it onto sticks and ceramics so that they could raise it in oyster beds. But actually producing the larvae—taking control of oyster reproduction, the same way we do with our other livestock animals? That was impossible until really quite recently.

GRABER: The first report of successful spawning of oysters came in 1879, from America’s first real oyster scientist, William K. Brown. He was summoned by the head of the Maryland Fish Commission to deal with the decline of oysters in the Chesapeake Bay. And so he spent a long and disappointing summer shucking oysters, hoping to find a baby in there. At the time, scientists believed lady oysters got pregnant just like lady women, so why couldn’t he find an oyster embryo in a single shell in the Chesapeake Bay?

TWILLEY: History does not record why William Brown decided to scrape out the sperm and eggs from ripe oysters, put them in a jar full of water, and give them a stir. But he did—and within just a couple of hours, he could see the fertilized eggs starting to grow. Of course, it took another 100 years, and yet more decline in the supply of wild oysters, before West Coast researchers figured out how to take artificial oyster reproduction to scale. But today’s commercial hatcheries are basically a big, high-tech version of William Brown’s glass jar.

JACOBSEN: They basically take the, you know, the studliest moms and dads, put them in a little hot tub together, turn up the water so the oysters think it’s high summer, which is breeding season. All the sperm and eggs get shot out into this little hot tub, and so you get really high success rates and then they put in crushed sand or shell for the oysters to attach to and then that seed which looks just like grains of sand is what they start in their nurseries and then grow the oysters up from there.

TWILLEY: At this point, the oysters are so tiny that 10,000 of them fit in a little baggie.

JACOBSEN: So you take those little sand grain oysters and you put them in a little upweller system, so which is just basically just a plastic barrel, they’ll be underneath docks where there’ll be a little trap door. You open up the trap door and there’s these plastic barrels that are sunk down. There’s a little pump that’s pumping water constantly in and out so that they—there’s a fresh source of food and you’ve got these little tiny grains of sand that then turn into little sesame seeds in a few days, and they’ll like double in size each day at that stage. So there’s a lot of like cleaning out the oyster poop from the oyster tanks and transferring the oysters to the next size barrel in those early early weeks.

GRABER: Then, once the oysters grow to the size of like corn kernels, the farmers transfer them into mesh bags, out in the ocean, wherever their farm is.

TWILLEY: And that, my friends, is how you grow an oyster in today’s high tech world. But really, the invention of this whole hatchery-mesh bag oyster growing system led to an oyster revolution. The mesh bags keep your oysters together so you don’t lose them, and they help protect the oysters from predators.But the really big deal about mesh bags is that they mean you can grow oysters anywhere because you don’t need a nice shallow bay for the oysters to attach themselves to anymore.

JACOBSEN: In fact many oysters today never touch the bottom because they’re grown in floating trays out—especially out in British Columbia and Washington State. They’re just in 60, 80 foot deep bays in plastic trays that are dropped down from rafts. So they have a very different look to them because of that environment. But it means that you can grow oysters anywhere now.

GRABER: So the invention of this hatchery-mesh bag method not only increased production, but it really expanded the range of possible oyster flavors by allowing us to grow the bivalves in entirely new environments. Even more recently, oyster farmers have developed a bunch of new farming techniques that also change oyster flavor and texture.

JACOBSEN: Part of the oyster renaissance is that farmers have gotten much more sophisticated about what they do in those stages to affect the final oyster because it can make a huge difference. Like, if you—if you just keep them in bags on the surface, it’s a pretty easy environment for them, they’re going to grow long quickly. And the oyster also if it grows too quickly it kind of doesn’t have that much essence to it.

TWILLEY: So instead, farmers put the oysters down on the bottom of the bay where they can’t get as much food. They grow much more slowly and end up tasting far more interesting.

GRABER: And there’s a new trick that oyster farmers have also just recently introduced: tumbling.

JACOBSEN: You can attach it to a line that’s sort of right at the mid tide line and attach a float to it so that when the tides go up and down, the float goes up and down and it basically tumbles the bag of oysters around the line and constantly jostles them

TWILLEY: Or you can do what some farmers do, and put the oysters in a cement mixer to slosh them round and round. There’s a surprising number of oyster tumbling videos on YouTube, if you’re curious—it’s sort of hypnotic in that way that watching a washing machine can be.

JACOBSEN: And what that does is it costs it constantly chips up the oysters growing edge. It’s almost like polishing rocks where all the oyster shells are getting smacked together as they go up and down and around and around in the tides. And so you’re getting a much smoother shaped oyster shell that looks almost polished. It’s really beautiful. But it’s also actually changing the nature of the oyster because oysters like they like to have their shells cracked open and be feeding. But if they get knocked they assume that a predator is trying to get them so they clamp shut real fast. So in this environment where they’re getting flipped around, they’re getting knocked a lot and they’re constantly kind of opening and then shutting their shells. It’s actually kind of like pilates for oysters. It literally builds their muscle because they’re working their muscles so much harder. So those oysters are smaller, they have really polished shells and they have really developed muscles inside. They’ll be like 50 percent muscle instead of 20 percent muscle. And so they tend to have a very firm sweet flavor to them.

TWILLEY: So these new farming techniques are introducing new textures and flavors to oysters. But there’s also oyster breeding.

JACOBSEN:  The first big oyster breeding breakthrough was a guy named Stan Allen at the Virginia Institute of Marine Sciences a few decades back perfected the triploid oyster, which is the sexless oyster. Triploid oysters have three sets of chromosomes so they’re neither male nor female. And what that means is that in summer when the water warms up and all the other oysters thoughts turn to the birds and bees, triploid oysters couldn’t care less. They just keep eating. So they’re kind of like steer, they they just keep fattening through the summer. So especially in the south with the warmer waters, those have been a big breakthrough because they they make for a really nice summer oyster. But now what you’re seeing, and this is really a first, is oysters being sort of like being bred uniquely for an area or for a farm.

GRABER: In the past only a handful of hatcheries bred oysters for all the farms. Which meant that all the farms were buying the same genetic stock each year.

TWILLEY: But now, there are more and more small boutique hatcheries, and some farms even have their own hatcheries, and are breeding their own, unique oysters.

JACOBSEN: This is brand new and partly why I think we’re sort of into uncharted waters in the oyster world is we’re now getting farms with very distinct lines of oysters on them with their own characteristics. So we’re getting more and more diversity.

GRABER: And just as farmers were perfect the hatching and the finishing and the breeding, Americans were getting ready to fall in love with oysters.

JACOBSEN: I think sushi helped for sure. Like I remember being weirded out by sushi at one point way back and once you fall in love sushi then raw fish is fine so —oysters are a little weirder than raw fish, muscle, but they’re still you know they’re within the whole sushi realm. So I think that helped for sure.

TWILLEY: But it wasn’t just our newfound appreciation for dragon rolls that helped spur the oyster renaissance.

JACOBSEN: It was what I kind of call the good food movement, you know, which hit in so many different areas around then. When people started thinking a lot more about where their food came from and about the environment that was producing their food, and kind of wanted to connect with that. So oysters kind of became this great way to get back in touch with that world. And at the same time people were getting much more savvy about wine. We’re thinking about terroir and oysters are the food that kind of best expresses terroir, merroir or whatever you want to call it. So then that’s when you started to get all these different oyster names and these new oyster growers and a lot more experimentation in the industry.

GRABER: And today you have hundreds of varieties, all with their own names, like we said, and all with their own merroir. Or, you know, taste—the taste that’s influenced by the species and the water and what the oysters are eating and how the farmers grow them.

TWILLEY: In short, it’s a golden age for oyster lovers. And you can feel good about eating all these farmed oysters because they’re actually leaving the ocean cleaner than they found it. Rowan explained.

JACOBSEN: So let’s go back to their lifestyle thing where they’re in the water all day filtering out phytoplankton. So they’re incredibly good at cleaning water, at filtering it. So they’re kind of like little pool filters that way. Self-propelled self-perpetuating pool filters. One adult Eastern oyster can filter like 40 or 50 gallons of water a day through itself, pulling out all of the tiny particles and getting the water a lot cleaner. And when the water is clear sunlight can penetrate a lot better and that allows seagrass to grow from the bottom and sea grasses are sort of the other key to this whole intertidal ecosystem.

GRABER: And oysters don’t just clean the water. Their reefs provide incredibly important habitat.

JACOBSEN: Back in the day when we had oyster reefs that were 20 miles long, they’re very much like coral reefs do in tropical waters. You’ve got this complex habitat of limestone basically with lots of little tiny crevices in it—very good hiding places for all the little juvenile and small organisms in the sea. So that really was kind of like the condominiums of the ocean where a lot of creatures would get their start was hiding in these oyster reefs. And then birds would come and feed on the oyster reefs, they were really the center of that ecosystem.

TWILLEY: And at the same time the oyster reefs were providing all this habitat, they were also acting as a natural breakwater, like a buffer against storm surges. Part of the reason that hurricanes seem to be causing so much more damage in places like Louisiana is because the oyster reefs that were protecting the land are gone.

JACOBSEN: And not only were they a breakwater, but they were a self-healing breakwater that even if there was a big storm that would blow a hole they would reseal it, I mean oysters colonized it. So that’s part of the reason that there’s a lot of oyster restoration efforts now is to get that sort of reef barrier back up and running.

GRABER: Oysters are quite possibly the perfect food—they taste great, they’re good for you, they clean the water, and their reefs provide homes for other baby fish and protect the coast from storms. But it isn’t all sunshine and rainbows in oyster land—they do still face a major threat. This time it isn’t how many we’re eating, it’s climate change.

JACOBSEN: So as carbon levels go up in the atmosphere, the oceans absorb a lot of that carbon dioxide and it turns their water more acidic. That acid eats away at any kind of shell that’s in the water because all the shell whether in coral reefs or oysters or anything else, it’s all—it’s basically like you know like an antacid pill, so it just dissolves in carbon dioxide. And there was huge, huge mortality rates in the hatcheries on the West Coast a few years ago because they just got a big hit of really acidic water. And very few oysters made it at all one year.

TWILLEY: Climate change also intensifies the diseases that oysters face, so that’s not good. But even with those challenges, oysters are really kind of the food of the future. Delicious, nutritious, and good for the environment. If you’re not eating them already, I really want you to consider it. You probably should be.

GRABER: Maybe some of you are afraid of bad oysters. I have a good friend who, after she tried her first, she was up nearly all night worrying that she had poisoned herself.

JACOBSEN: Okay, so yes, so people ask me all the time how do I avoid getting a bad oyster. This is another thing that I don’t quite get because if you have a really bad oyster you know it the moment you pop that shell a little bit because you clear that room out. A really bad oyster is just, you know, foulness incarnate. And people can tell 50 feet away. It’s just like the smell of rotting flesh.

TWILLEY:  That seems straightforward: don’t eat stinky oysters. Okay, so let’s say you do want to try oysters, but maybe you’re still a little nervous about the slime factor.

JACOBSEN:  I tend to recommend small oysters. Small oysters are definitely less intimidating. Especially if it’s just like a small salty oyster. Then it’s pretty easy. So I’ve had a lot of success getting small salty oysters into oyster virgins and then they convert pretty quick. It’s really fun to to bring people over to the other side of the fence. But now is actually really like the best time ever for for getting people onto that side of the fence because there are more of those small cute oysters on the market than ever before. The whole market is tending to skew toward less intimidating oysters which the, you know, the old school people grumble about. But I think it’s probably a good thing.

GRABER: I was an oyster virgin until 2010. I tried them in France, and then a couple of months later—this is when I really became genuinely obsessed—I walked into Island Creek Oyster Bar in Boston and had oysters from Cape Cod.

JACOBSEN: LAUGHS Those are my favorite oysters too. Well, first you had the best experience—if Island Creek was your first oyster experience that’s you know—very few people have such a perfect entry into oysters, because that was the oyster bar that kind of raised the bar—sorry, bad sentence there—but they raised the bar on oyster quality and attention to oysters. They were kind of the first oyster bar to put the names of the growers on there and to really pay attention to merroir and to have servers who just knew their stuff down pretty deep and could explain everything to you. That really—that is just a spectacular place for your first oysters. So you get the you know oysters in prime condition and I think that that is—your odds of becoming obsessed are a lot higher. And especially if it’s one of those Cape Cod oysters. Cape Cod is just like oyster heaven. It’s—you know all it is is one giant long spit of sand basically left over from glacial days, and then slowly descending on either side and with really nice tides that wash in lots of fresh water twice a day on the high tide, this perfectly salty Atlantic water. There’s virtually no rivers on Cape Cod. There’s some freshwater springs but there’s no real rivers. So every oyster coming out of Cape Cod is just wicked salty as they say out there. It’s kind of just like a perfect storm of conditions to grow oysters. They all tend to be great in the same way, like there’s not a huge amount of diversity but they’re all going to be great very briny oysters that taste like you just got smacked by the Atlantic Ocean and go great with beer.

TWILLEY: Since you got to hear about Cynthia’s first time, you’re going to hear about mine. Which was on the West Coast, at one of the two oyster farms in Tomales Bay, which is this skinny little bay north of San Francisco where the San Andreas fault meets the ocean.

JACOBSEN: They were the first to do the picnic tables on the water, shuck your own oysters. So they’re oyster farms but you just go there, buy a bag of oysters and they’ll loan your knife or the knife is actually like attached to the picnic table and you shuck away. And it’s this stunning spot where you’re looking out at those—those you know golden grassy hills and then the water’s coming in and you can actually see the oyster farmers at work out on the water. It’s just a spectacular moment. And the oysters are being farmed you know half a mile away or less quarter mile away. So what you’re smelling as the breeze comes off the water is the exact same smell as the oysters that you’re eating. So it’s all just like of a piece. You know, it’s like, hard to differentiate between the oysters and the place which to me is you know what you what your goal is. Those choices of course are Pacific oysters. So totally different than the the East Coast oysters. Instead of that like briny wave at the beach thing, they’re much more cucumbery and melons scented and sweet. Really. They call them sweetwaters and they really do have an amazing sweetness on the finish.

GRABER: Oh my god!

TWILLEY: And now you’ll have to excuse us while we go get some oysters

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TWILLEY: Thanks to Rowan Jacobsen, the author of the new book The Essential Oyster: A Salty Appreciation of Taste and Temptation. It’s a gorgeously illustrated tour through hundreds of oyster varieties. You’ll want to page through it at home and then, once you’ve worked up an appetite, bring it along with you to your nearest oyster bar.

GRABER: In two weeks, we’ll be back with an episode about a cuisine that most Americans rarely if ever get the chance to eat. Which is kind of ridiculous, because it is quite literally the native American cuisine. We’ll meet the farmers, seed-savers, researchers, activists, and chefs who are trying to change that, and solve some major health challenges in the Native American community along the way.

SEAN SHERMAN: And you know Native American food will be a viable option for the future. And we can’t really wait for that day when we can drive across the country and there will be a whole bunch of Native American restaurants out there. and really showcasing the huge variation and variety of food flavor and culture and history we have all across the board.