Oysters & Aquaculture: On the Half Shell – Lab 073

People think it's back to school season, but it's really a different season for me.

Yeah, because we're not thinking about going to school anymore.

Thankful you can keep the trapper keeper.

I don't need it. I don't envy y'all that are thinking about Oh yeah, I gotta, you know, start thinking about classes. No, that time in my lives are ova.

But there is a more interesting and pressing time of our life, and it is a celebration for us. Tomorrow is National Oyster Day.

Zakeia and I have talked about food many a time on this podcast. Yes, and my friend also introduced me to oysters when I met her in grad school and changed my whole entire life. Did you know that that I had never had an oyster? I had never had an oyster. I didn't know that you didn't. We did a lot of culinary first together, Yes, but venturing into oysters was something that was new and surprisingly delicious for

It's good and based on the volume of oysters we're eating, we had to really ask like, what's going on with the oysters? Should we cut back? Should we you know, scale up the consumption? What's the deal?

I know? Right?

So, you know, we had to bring it to the lab. I'm t T and I'm Zachiah and from Spotify.

This is Dope Labs.

Welcome to Dope Labs, a weekly podcast that mixes hardcore science, pop culture, and a healthy dosa friendship.

This week, we're talking all about aquaculture specifically, we really wanted to know more about oysters, our favorite delicacy, and how cultivating these shellfish fits into our economy, the environment and changing climate.

Okay, so we have a question for you. Where are you on the shellfish spectrum? Are you a regular consumer of bivalves and crustaceans? So do you eat a lot of shrimp and crab and oysters? Are you a newbie? Have you just recently had your first oyster? Or are you keeping the industry afloat like me and TT? Be sure to answer the poll in the app right now. Let us know, let's get into the recitation, all right, TT, what do we know?

Well? I think I know that it is oyster season and that National Oyster Day is August fifth.

And we love the oysters, okay, but the habitat are our friends, the oysters. It's disappearing and a lot of that is related to land development, wetland lost, and pollution. We know that from our previous episode with doctor Ayana Elizabeth Johnson and we talked about this a little bit with doctor Nicholas Reyo.

Yeah we did. That feels like forever ago, but yes, we have touched on this before. We also know that aquaculture is not just about oysters, even though we talk about oysters a lot. It's about the cultivation of fish, shellfish, and aquatic plants.

But we know oysters are a huge part of the aquaculture movement. It feels like it's really growing, but I think that's about it. That's all we know.

We are laser focused on those oysters.

So let's jump into what we want to know tt So, I.

Want to know how aquaculture has changed over the years and when did people start eating oysters.

A long time ago? It was sustainable then, but is it sustainable now? If we consider what we know about dwindling populations, and we know what we're trying to do with oyster farming and aquaculture. A lot of times when we try to have interventions, we always end up messing up the environment, right, Like is this sustainable?

Is this helpful? Like I'm such a good person, I'm helping Meanwhile, dump the farm?

Right?

And then my question is as all things are affected by climate change, we see everything is affected by it. I want to know how aquaculture is affected by climate change and what scientists are doing to combat that.

And as the world's population grows, can aquaculture help us feed our planet. Let's jump into the dissections.

Our guest for today's lab is doctor Bill Walton.

My name is Bill Walton, the ACUFF Professor of Marine Science and the shell Fish Aquaculture Program Coordinator at the Virginia Institute of Marine Science here in Virginia out of College of William and Mary.

Doctor Walton works with shellfish farmers, resource managers, and organizations to address the challenges of shellfish aquaculture and also identifies opportunities to develop this industry. Before we dive into our questions, we need to understand what aquaculture actually is.

Aquaculture is the raising of organisms of any type, and that's plants, animals in an aquatic or marine environment. That means that you're doing something during the life cycle of that organism to help it succeed, so you've intervened in some way in that.

So, as doctor Walton said, aquaculture is when people farm aquatic species. So it could be fish, shellfish, or even plants, and that can happen in both freshwater or marine environments.

And people use aquaculture to pursue different goals like habitat restoration, trying to help threatened or endangered species, and of course for food.

You know, I think my first introduction to aquaculture was when there was like farmed tilapia and farmed salmon, And so when I think about aquaculture, what comes to mind for me is like multiple tanks of PVC piping swimming pools of fish. Like that's what I think of. So what does aquaculture look like for shellfish?

Let's take a minute to talk about the history of aquaculture. Humans have altered marine and freshwater environments in pursuit of food for thousands of years. We see this from indigenous communities around the world who use different cultivation methods to increase their harvests.

But one of the things we also know is that in the last century we've had a lot of human intervention that has affected aquatic species, and so in response to that, we've seen a rapid acceleration in aquatic farming.

There's been a drastic decline in oyster populations all over the world. Example, oyster populations are just a fraction of what they were like in the nineteen hundreds, and three fourths of the oyster eaves were lost due to over harvesting from eighteen sixty to nineteen twenty. That's just sixty years. That's someone's lifetime. We talked about how humans have disrupted the food system in our episode on biodiversity with doctor

Oysters are mollusks or bivalves, and that's just a fancy way of saying they have two shells.

And humans have developed a lot of different ways to grow and maintain these creatures.

To understand how aquaculture works. We need to get an idea of the oyster life cycle in general. When oysters spawn, they kick out the eggs and sperm into the water, and those eggs and sperm meat fertilizing the egg and then you get a lot of growth in tiny little larvae floating in the water. And so the larvae float through the water until they can attach to a hard surface, and often they're attaching to other oyster shells.

And once they're attached, those little oysters are called spat, and these spat don't have shells, so once they're settled, they start to put all their energy into their shell growth, and they do that by isolating calcium carbonate from the water column.

And so when those generations of oysters grow, one set of oysters on top of another set on top of another set, you get shell clusters and those are called oyster reefs or oyster beds, and the oysters grow there for the rest of their lives. And this is not a short growth process. The oysters that we see at the table are usually about two to three years old because they're growing at about an inch a year.

And this life cycle that we just describe, it's full of a lot of dangers.

Most of those, in fact would be lost. They'd either be eaten or washed away. They wouldn't survive. But in a hatchery, we can make sure that most of them survived.

So taking all of this into account, we ask doctor Walton to describe what a modern oyster aquaculture setup actually looks like. And the hatchery is the first step of modern oyster aquaculture, and a hatcherie is an environment that encourages the oysters to reproduce.

Hatcheries do that by mimicking and amplifying what happens naturally, so they're increasing the yield of each batch.

We induce them to spawn. That's one way to do it, where you just change the temperature for the oysters and you convince them that it's spring and so they spawn for you. And that should be more romantic than it is. But essentially oyster spawning is throwing their gam meats out into the ocean or the river, and those gam meats have to find each other up in the water.

Those are called broadcast spawners. In the water, most of the spawn would be lost. They're going to be eaten by other fish or different things that are in the water, or just simply washed away with the tide. But in a hatchery, you don't have that same problem.

And at that point we care the babies called farv We care for them for about two weeks and we make sure they have all the food and oxygen and clean water that they need, and then they go through what's called metamorphosis. And so some audience members will remember

So at the hatchery they're just increasing the survival rate of these oysters. And once that process takes place, that's what we call a seed, and those are the baby oysters. And if you're an oyster farmer, you're gonna then buy those seeds for you to grow oysters. And so you can buy them, buy the thousands or millions, and then you can start to raise them.

I don't usually like to think about buying things on the thousands or millions, but you can buy a thousand of those oysters for about ten to twenty dollars.

Wow, right, that's cheap.

That is that's incredible value.

Do I want a little oysters?

We have to find a place to put them, because when you're farming oysters, it seems like they need to be in naturally occurring water. Bathtub water won't do.

Okay, my Brita filter won't work. So those indoor farms that we had talked about and imagined all the oysters being grown in, they pop into our minds when we think about aquaculture, but they aren't really economically viable. And that's because when you provide that oyster seed with food and oxygen, it grows into a really hungry oyster and you need more space that an indoor environment might not be able to provide.

And doctor Walton says, you also need a lot more food. Very quickly juvenile oyster becomes feed me see more little shops.

So you have this like incredible demand for food. These shellfish are really good at eating the microscopic plants. And so when you start to scale that up and say, okay, I'll start a factory for shellfish in the middle of the country, and I'm going to try to like raise all the food for them under controlled conditions. Technically, I guess you could probably do it, but I have a very hard time imagining that somebody could turn that into

So the economic forces behind aquaculture push people to use offshore locations in natural waters because it's actually more financially feasible, and like you were saying, better for the oyster, because there's more food available naturally.

When I'm first growing your seed, they're about one millimeter and so that's you can see them, but they're very small. They look like grains of sand. You might on that screen. You might be putting a quarter of a million to half a million of those grains of sand on one and the seawater that's flowing by them is going to bring them enough food and oxygen that they'll grow.

And doctor Walton is being modest. Oysters require a lot of food and oxygen. You'd need a lot of money to keep those bivalves fed. Like if you are going to be a farmer, there's places that you can go where they've taken little seeds and developed them into seedlings. Yeah, and the oyster farmer is buying the seedlings and then cultivating those into big It's like.

What people do for their gardens. When you want to start, you know, growing tomatoes or if you want to grow basil, maybe you'll go to a nursery that have already started growing them in those little plastic containers and then you take it home and you plant it in your garden and then you can go and start growing your own vegetable garden or growing your own are growing whatever you can get the bulbs or the seeds that have already started to grow, and you put them that someone has

And you know, just like a home garden. For oyster farmers, there are multiple setups that they can develop to grow those oysters. So one of the first examples that doctor Walton walked us through is an oyster farm.

So we're gonna be talking broadly about two different systems on bottom farms and off bottom farms, not to be confused with bikini bottom farms. So if we're the oyster farmers and we have these seeds, we have to think about where they go. And on bottom farming, the farmers are creating a hospitable area at the bottom of the water body for their oysters to grow.

We get in a boat and we go out of the river here and you might just see corner posts like poles sticking up out of the water, and I would just have to assure you that there are private leases, what we call private leases, that are being farmed on the bottom there.

So those seeds that you've purchased, those little baby oysters, the kid oysters, you're trying to make your land more attractive so that they stay there.

And those look very much like what a natural oyster bed looks like. The typical thing actually that you put down would be oyster shell. So you essentially take the bottom that was soft mud, and because it's your lease, you decide that you're going to improve that bottom by putting oyster shell on it. We call that culting. And when you culch, you're improving that habitat so that you're

So what they're doing is culture. They're trying to improve the habitat. This is the equivalent of you adding fertilizer or something to your soil in the area where you are. Oysters want something to attach to, so you add things in onto the bottom of the water where you're going to be growing them to make it attractive for the oysters. Another form of on bottom farming is when cages or mesh containers sit on the seafloor.

You might see a number of buoys on the surface, and that would look a little bit like if we were going out and we saw crab traps or lobster traps somewhere, and in that case, we'd bring the boat up and we would go to those buoys. In there, it's a cage or a basket that's sitting on the bottom and the oysters are sitting inside those bags, and we would bring that. We'd bring that cage up to the surface and you'd see that it's full of oysters.

So it's a mesh container that the oysters are living in but since it's sitting on the bottom of the ocean, other little friends that are also living in the ocean can get in there as well. You know, some uninvited guests, but I guess they're welcome.

Yes, And although it may seem like a nuisance, this is actually great because this is evidence that for aquaculture farming, and specifically oyster farming, these mesh containers create habitat for other critters, so other members of this ecosystem to also live and thrive. So, yes, you're doing it for the oysters, but the homies are coming along too, and they bringing groceries.

I was just at of some farms recently and we spent time picking up all the eels that had come up with it that immediately started to bail out of the gauge because they didn't want to be out of the water, and so we just scooped them up and got them back overboard. So you see lots of marine life in amongst these things.

All right. So that's farming on the bottom of the seafloor or a river bit off. Bottom farming is when the shellfish grow in a mesh container suspend it near the surface of the water.

The other version that somebody might see would be going out on the water and seeing baskets or bags floating

Now, we didn't cover all the different ways that people farm oysters, because there are some in between methods that involve being in the water and then out of the water. Just know that people are getting to the oysters a lot of different ways.

It's really cool to hear about how these farmers are able to farm oysters in so many different ways that actually mimic their natural environment.

This makes a lot more sense than my original idea of swimming pools of oysters. The elephant in the room here is that most of our oyster reefs and most of our environment that existed for oysters to grow on and to thrive and flourish is gone. Right, So you have farmers creating these artificial reefs with mesh bags and cages that are benefiting oysters and other organisms and other

We're going to take a quick break, and when we get back, we'll talk about the economics around aquaculture and its place in a warming planet. On next week's Lab, we're talking all about forever chemicals, what they are, where there are, and how we can move around them.

In the meantime, let's get back to the lab. We've been talking to doctor Bill Walton about oyster farming and aquaculture. Now we're going to consider what aquaculture means for a growing population.

It's a really good question. Does aquaculture fit the bill? Can it help us feed the world as our population continues to grow?

The world population is growing, we know that we have to provide food and that there's to me just sort of the ethical requirement of thinking of ways how do we produce that food in a way that also minimizes the environmental impact while we do that. When we look to the oceans, we know that the total world harvest from fisheries has leveled off essentially, I think at least

Can, getting as much as we can so are we saying it's leveled out or is decreasing now did it used to be increasing like or do we have more people eating fish and they used to so the demand I have some questions.

The number of wild caught fish and shellfish has plateaued, so it hasn't stayed, but the amount of fish and other organisms harvested through aquaculture has grown, and doctor Walton says aquaculture could be a major source of sustainable food. You know what I think about a lot, what's that the growing population of this world. I think that we have to start thinking about how we're going to produce enough food as our population is growing, like, we have

If anybody who likes eating shellfish, let's say raw oysters, if you've gone into a raw bar in a city, these are expensive items. The typical person might think when they think marine aquaculture, they might think salmon, and in fact that's relatively low in terms of value total value compared to some of the other species that we raise. So shellfish are sort of one of the big things

So, not only is the need to produce more food a concern, but economic forces are also pushing this innovation around aquaculture. It's important to understand how aquaculture and the changes to our coastline is impacting people economically. Doctor Walton says that US aquaculture is actually not a world leader. We're currently sixteenth in the world in terms of production, and he says that's surprising given how much coastline we have.

You're doing this out in shared waters. As a community, you need to decide that you want to do it. It has to be permitted that said, of the aquaculture that we do do in the US, in the marine environment, it is dominated by harvest of oysters and clams and muscles.

Okay, so we're not going to solve world hunger with oysters, but aquaculture technology could help develop more food and sustainably.

Oysters are a really healthy food, right, and when you think about what it takes to produce that protein, it's probably a good choice as a society to be thinking about that. I'd like to get there, but we're not there.

So we have this situation where as doctor Walton said, we have a pretty pricey food, oysters. In this case, let's be in sold to restaurants where people are buying them for two or three dollars per oyster, and sometimes that's the happy hour deal. So how do you feel good about cultivating something that's so expensive.

The way I feel good about that is not only the environmental impact that I think is as I said, I think is a net positive for the coastal environment.

When doctor Walton first got into shellfish aquaculture, one thing that stood out to him was that oyster growers were really invested in water quality and he thinks that's a great aspect of the industry.

And based on what he says so far, that makes sense. Right. Good water is important for these communities livelihoods.

To have somebody come in and be literally invested in the water quality arguing for it. I just love that. I love that we have essentially stewards of our coastal waters. Yes, they're growing something and they're harvesting something there, but they're also really some of our best advocates for water quality out there as well.

It's such an amazing point to make and I think really important, and I'm glad that doctor Walton highlighted it. These farms and cultivation areas affect people and communities locally.

I think of places that I've worked, for example, with shrimping, and the grandparent who runs the shrimping boat is not encouraging their grandchildren to become shrimpers. When those communities start to have that movement away from fisheries, what happens to them.

Doctor Walton says that aquaculture is a way for people to stay involved and work in coastal places, many of which are rural, and we're seeing more and more rural communities turning to aquaculture as an industry.

I think there is again this sort of social element of if we can find ways that people can make a living working on the water to provide food in a way that's environmentally sustainable, that keeps those communities thriving and alive. Honestly, I think the biggest part of it for me is that it's something that's giving communities the option of do they want to adopt another way of bringing in food from the sea that presents ways for young people in that community to go have careers and

Doctor Walton is saying this is a sustainable industry that can bolster rural economies and improve the environment. Sounds almost too good to be true, right.

Remember, all of these organisms are working in a beautiful symphony together and they balance each other out within their ecosystems. If an oyster farmer is not appropriately managing their oyster farm and they are creating all of these oysters, these oysters are eating up all of the nutrients that are in their surrounding area, and what that does is create

And that's just one example of the importance of this balance. You know, this lab, we're focusing on shellfish aquaculture, but there have been concerns about finfish aquaculture, so growing fish that have fans, so thinksmon and catfish and what that can mean for other wildfish in the area. We have more info about that in the show notes, so be sure to check it out at Dope labspodcast dot com.

Well, there are some other factors to consider when thinking about oysters, specifically climate change. We act doctor Walton how climate change has impacted aquaculture and how the industry has to adjust, and it's really interesting. In some areas, warmer conditions might actually benefit the farms at least in the short term.

There may be longer growing seasons, et cetera, et cetera. But when we think about climate change, that change is hard and certainly rising temperatures can be stressful for oysters in certain environments, and we know that that affects how much dissolved oxygen is in the water, so there's concern about that and that by the way that could function differently at the surface of the water versus the bottom

So climate change isn't just directly affecting whether shellfish survive and how they survive, but it's also changing the farming techniques that farmers are using, and they have to change if they want to continue operating in this industry.

This is a little complicated. Rising temperatures alone may not pose a problem for oysters, but other changes caused by climate shifts could, like heavier rainfall. Because these oyster farms are so integrated into the natural environment, they're sensitive to shifts in the weather. Doctor Walton says rain changes things, and also if it gets warm, it changes things.

So oysters are pretty good at tolerating changes in salinity. But if you are also raising the temperature on those oysters at the same time that they're getting stressed by the freshwater inputs, we have seen mortalities from those combinations, and certainly that's been associated with the idea that that could belimate change. The other big thing that you hear

pH is an indicator of how acidic or alkaline water is, and on average the ocean is about twenty five percent more acidic than it was a couple centuries ago. Now that's bad news for marine life because the acid that's forming in that water decreases the amount of carbonate that's available for them to build shells and skeletons. Doctor Walton says, the larvae are really vulnerable to these changes.

If I to get to a reef and the oysters were dissolving away, that's pretty obvious, right. I'm not saying that that's happening, but you could see that microscopic larvae having problems in the water that you can't see is a harder problem to identify in the first place. So I think that's one of the things that some hatcheries.

That's such a great point that doctor Walton is making that we can't really see this lack of carbonate in the water because we only see the shellfish that make it. We don't know which ones aren't making it. And it's interesting that hatcheries are trying to treat their water so that larvae have a better chance of survival. Doctor Walton said that this kind of aquaculture can actually benefit habitats.

And if we think about it, oysters are solving a lot of problems. Some of them we can't see, and some of them we can't. But doctor Walton gave us a couple of really good examples.

Shellfish are actually really good at cleaning up water.

The other thing that I think has to happen with that is that they do eat that microscopic plants and they turn it into oyster. That to me is very similar to when you put sheep out into an overgrown pasture and they graze the pasture down. Shellfish are essentially that.

Another example is a lack of habitat for other organisms that are living in the water. This reminds me of our episode on biodiversity. I mean, we've already talked about it before, but I'll bring it up again where we talked about how all of these organisms, all of these animals are not living in a vacuum. We all live together and we are all serving a purpose, you know.

Well, it turns out that the shellfish farm doesn't look like an oyster reef to us, but a lot of the organisms in the water perceive it is very similar. If you're a little juvenile blue crab or a little juvenile fish or shrimp, those are tough places to make a living because it's you have nothing to protect you. There's no safe corner.

So the oyster farms become the habitat that protects those other sea creatures.

And if you think about it, the shellfish farm that is out for example, on the eastern shore of Virginia, those clams or those oysters are filtering that water the same way that a reef would be. They eat the excess food out of the water, which potentially can help

I know we've said it before TT, but I think we got to say it again. Oysters really feel like the true MVPs.

Honestly, they're doing so much for the culture, the aquaculture, and.

You know, human efforts to improve the environment. Often we don't get it right. We don't always get it right. It's usually tied to some type of economic benefit, you know, but it feels like here, I mean, I could be missing something, but it feels like it's a win win. Okay, it's time for the one thing.

Okay, Zee, what's our one thing this week?

Our one thing this week is really capturing the vibe of this lab and it is an Instagram page Black Girls the letter in Oysters. So black Girls in Oysters, and this page is giving you all the vibes, all the tips, recipes, suggestions. If you are into oysters like we are, they recently had a real and it says all the dudes and don'ts around eating oysters and I just loved it. That's it for Lab seventy three. Be

And don't forget that there is so much more to dig into on our website. There'll be a cheap heat for today's lab, additional links and resources in the show notes. Plus you can sign up for our newsletter check it out at Dope labspodcast dot com. Special thanks to today's guest expert, doctor Bill Walton. You can find doctor Walton at doctor Underscore Oyster, and you can find us on Twitter and Instagram at Dope Labs podcast.

TT's on Twitter and Instagram at dr Underscore t Sho.

And you can find Zakia at Z said. So Dope Labs is a Spotify original production from Mega Ownmedia Group.

Our producers are Jenny Ratilit Mass and Lydia Smith of Wave Runner Studios.

Editing and sound design by Rob Smercy.

Mixing by Hannes Brown.

Original music composed and produced by Taka Yasuzawa and Alex Sugier. From Spotify, Creative producers Miguel Contraras and Grace Dielia. Special thanks to Shirley Ramos, Jess Borison, yasmin Afifi, Kamu Elolia, Till krat Key and Brian Marquis. Executive producers from Mega Own Media Group are us T T show Dia and Zakiah Wattley.