Today is the last class of your current eight class set. We will start class with a casual conversation. Our material today is about aquaculture. I have included a transcript. Listen to as much as you can.. Our reading today is about friendship. Please read as much as you can.
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ANNOUNCER: You're listening to Short Wave from NPR.
REGINA BARBER: Hey, Short Wavers. Regina Barber here. And today, I'm joined NPR global health reporter, Jonathan Lambert. Hey, Jon.
JONATHAN LAMBERT: Hey, Gina.
BARBER: So you're here a story from Senegal.
LAMBERT: Yeah. I traveled there earlier this year to witness the early stages of an ambitious experiment.
BARBER: OK. I'm very curious. What is this experiment?
LAMBERT: So a team of Senegalese and international researchers are trying to see if they can solve three big problems that are affecting rice farmers and Senegal more broadly with one simple solution.
BARBER: Ooh. OK. Before the solution, what are the problems?
LAMBERT: A debilitating disease, the need to boost rice production in Senegal, and poverty among rice farmers in the country.
BARBER: Ooh. OK. So how are they solving these problems?
LAMBERT: With fish.
BARBER: [LAUGHS] I like it. OK. Fish. Tell me more.
LAMBERT: Yeah, specifically, putting fish-- like, hundreds of fish of a couple of different species-- into rice farms.
BARBER: That's so cool.
LAMBERT: Yeah. It's really cool. The research team behind this has done smaller pilot studies that showed this could be promising. And this year, they're really scaling up the experiment and testing it out across 60 rice fields. So I tagged along with a team as they set out before dawn from Saint-Louis, which is this town on the coast of Senegal, to pick up these fish and deliver them to one of those farms, about 100-some miles south of the Sahara Desert.
BARBER: Wow. You became a fishmonger, sort of.
LAMBERT: Kind of.
BARBER: So today on the show, how putting fish in rice farms could be a win-win-win for fighting a debilitating disease, boosting rice production, and reducing poverty.
LAMBERT: And why rice farming helped fuel a surge of this disease in the first place.
BARBER: You're listening to Short Wave, the science podcast from NPR.
[RELAXING MUSIC]
BARBER: OK. So, Jon, I want to back up to something you said earlier about these rice fields being pretty close to the Sahara. I thought rice needed lots of water. So isn't this area, like, maybe too deserty to grow rice?
LAMBERT: Yeah, that's a great question. This region is called the Sahel, and it's really hot and dusty. The exception is right around the Senegal River. It's still pretty hot, but it's a lot greener. And a lot of that green is from rice farms. But it wasn't always this way.
BARBER: So what changed that?
LAMBERT: So a series of dams that were built in the 1980s. Before the dams, there just wasn't really enough water to support rice farming during the dry season. After the dams, it became a lot easier, and rice farming flourished. But the dams also had a major unintended consequence-- a surge in schistosomiasis.
BARBER: I have no idea what that word means. What is it?
LAMBERT: It's a disease that's caused by this parasitic worm that spends part of its life in freshwater snails.
BARBER: Oh, no.
LAMBERT: Yeah, it's it's not great. When I was in Senegal, Kayla Kauffman, a Stanford disease ecologist who works on the project, dug up some of these snails in a rice field to show me.
BARBER: OK. So what did they look like?
LAMBERT: It's basically like your standard snail, but they can be pretty tiny, but they're still really dangerous. The parasite reproduces asexually inside the snail and then can slink out into the water by the thousands.
KAYLA KAUFFMAN: They then try to find a person that's waiting in the water, like a rice farmer. And then they burrow through that person's skin and then go on this complicated path through their body.
BARBER: This is horrifying.
LAMBERT: Yeah. And ultimately, the worms lay eggs in a person's intestines or urinary tract. And that can cause a slew of problems, from stomach pain to bladder cancer.
BARBER: Oh my gosh. This is like a horror movie. OK. And because the dams were built to keep around more water, did that make the disease worse?
LAMBERT: Yeah, totally, not just because the dams meant there was a lot more water and, thus, a lot more habitat for the snails. But the dams also cut off the migration root of a key predator-- prawns.
BARBER: So these prawns would be eating these worms?
LAMBERT: Yes, yes. So they were a major predator. And they're not, like, small prawns. They're, like, kind of big, like big crayfish. And they're pretty fierce snail eaters.
BARBER: Wow.
LAMBERT: And before the dams, they helped keep snail numbers in check. But after, Kauffman says that prawn numbers fell. And fewer prawns meant more snails and more schisto.
KAUFFMAN: The link between dam construction and increased schistosomiasis is really strong.
LAMBERT: Now this part of Senegal has among the highest burdens of schistosomiasis anywhere. For rice farmers, it's an occupational hazard. I spoke to one named Dgibi Dia at the farm that he's worked for four decades.
DGIBI DIA: [NON-ENGLISH SPEECH]
LAMBERT: He's saying that this always happens to us, since we are in the water for most of the time. He's had bad stomachaches, diarrhea, fever. It can affect him for weeks to months at a time.
BARBER: It sounds awful. How is it treated?
LAMBERT: So there is medicine to treat it, but he says it's hard for him to get it. Partially, that's because he's in a really rural part of Senegal, and partially, it's just expensive to get the drug. And it doesn't prevent reinfection. So farmers, because they're always going back into the water, they just get it again and again.
BARBER: Oh my gosh.
LAMBERT: That's where the fish solution I hinted at earlier comes in. One of the species researchers are testing out is called African bonytongue or heterosis.
BARBER: I love it. OK.
LAMBERT: Yeah. They're these--
BARBER: Tell me more.
LAMBERT: --big, kind of gnarly-looking fish, almost, like, prehistoric.
BARBER: Cool.
LAMBERT: Momy Seck Ndao, an environmental engineer on the project, told me that they're perfect for the job.
MOMY SECK NDAO: It's a species which can eat a lot of snails per days.
BARBER: OK. So the fish are kind of like, replacing the prawns as a predator.
LAMBERT: Yeah, exactly. Actually, some of the same researchers tried stocking some parts of the river that lost prawns with new ones earlier, like several years ago. But raising all those prawns proved really tricky. And the researchers think that raising all these fish will be easier. And the hope is that they'll eat enough snails in the rice farm to lower the risk of schistosome. Momy and her colleagues take measurements of the snail density in farms before adding the fish and'll do that again at the end of the season later this year. But getting these honkers into the rice challenging.
NDAO: Yes. [LAUGHS] Yes, and the heterosis is very, very crazy, very, very, very hard to-- to catch.
BARBER: Wow. I hear all this splashing. OK. So you mentioned multiple species are being added.
LAMBERT: Yeah. So the other species is tilapia. And hundreds of tilapia will be added to each field.
BARBER: Tilapia is such a, like, a staple for food, right? Do they eat snails too?
LAMBERT: Not really. They do eat a lot of the same stuff that snails eat, like algae, and so that competition could hurt the snails. But their main job isn't reducing schisto. It's pooping.
BARBER: You came place, Jon.
LAMBERT: Yeah. Here's Momy again.
NDAO: The feces of the fish, which is very important. It's a natural fertilizers.
LAMBERT: More fertilizer should mean more rice. That'd be great for the farmers and for Senegal as a whole. Because even with all the rice production that's happening in the Senegal River Valley, it's not enough to meet demand. The country still imports about half the rice it eats. And as a final bonus, the farmers can eat the fish themselves or sell them at the end of the season.
BARBER: I love this. Is there any cons to this? Because, like, you know how in other countries, you introduce a species to get rid of the other species, and then it's just like a, you know, invasive--
LAMBERT: Yeah. Because it's--
BARBER: --thing forever?
LAMBERT: That is a common pitfall of many attempts to try to solve a biological problem with a biological solution.
BARBER: Exactly.
LAMBERT: This one, when I posed this question to the researchers-- and they told me that because the rice farms are kind of like, a self-contained unit, there's less of a-- it's not like the fish are going to be, like, jumping out and causing other problems. And the fish--
BARBER: It's already human made, too, like--
LAMBERT: Yeah, yeah, yeah.
BARBER: --this rice paddy.
LAMBERT: It's, like, an artificial place. And so they're adding in this biological solution. That doesn't mean that there aren't things that could go wrong, but--
BARBER: Right. It's less.
LAMBERT: --they think that that potential is less because it's already in this sort of artificial, enclosed place.
BARBER: OK. All right. Well, at the beginning of the story, you talked about how you went somewhere to get the fish, and you brought it to the rice paddies. So, you know, in general, where are these fish coming from?
LAMBERT: Yeah. So the day that I was with the team, we set off from Saint-Louis, which is right on the coast, to a town called Dagana, which is about two hours away to a fish farm. And there, a fish farmer raises these tilapia. And the team caught nearly 2,000 of them and loaded them up into this big, green tank on the back of a pickup truck.
BARBER: So you were in this truck.
LAMBERT: I was in the truck. It actually stalled out a few times as we were trying to leave--
BARBER: Because it was so heavy?
LAMBERT: Because it was so heavy. And it's, like, really hot. And so I was worried, and the researchers were worried that it would-- like, the fish would bake in the sun. So we were kind of on, like-- it was a tight timeline to get the fish from the farm to the rice farm. But we made it.
BARBER: Awesome. OK. What about the other fish, the snail eaters?
LAMBERT: So those are actually trickier to get. They live naturally in rivers. And people have to go out and catch them, usually as juveniles, and then raise them from there. Like, it's harder to raise them in a fish farm setting. And along the way, we stopped at this smaller field site managed by the team to grab a few of those big fish.
BARBER: OK. So you take these fish. You drive up to the farm. What do you do now. Do you just, like, plop the fish into the rice fields?
LAMBERT: It's more like gently ease the fish into their new home. But--
BARBER: OK. How do you do that?
LAMBERT: --it's basically the same principle. They take them in buckets and, like, slowly submerge the buckets and then give the fish time to, like, swim out when they feel ready. It usually takes, like, 5 to 10 minutes.
BARBER: And what do the farmers feed them?
LAMBERT: Nothing. They don't feed them anything. The idea is to just kind of let the fish do their thing.
BARBER: Because they have to eat snails and algae and poop--
LAMBERT: Exactly.
BARBER: --and then, hopefully, be dinner for the farmers.
LAMBERT: Exactly. And this is happening across 60 rice fields for this whole season. And in each of those fields, the researchers will be collecting a ton of data. They're tracking the snails. They're measuring rice growth with drones.
BARBER: Oh.
LAMBERT: And they're closely tracking how the farmers are using the fish.
BARBER: OK. So the hope is that this reduces this disease-spreading snail population, it'll boost the rice, and also maybe the farmers' income?
LAMBERT: Yeah, yeah. And they have more reasons to be optimistic. For one, fish and rice have been raised together for centuries in Asia. And the benefits to rice yields are well documented there. It's pretty rare in Africa, but the researchers have done this experiment on a much smaller scale over the past few years. And they actually published some promising data just a couple of months ago.
BARBER: Ooh. What did they find?
LAMBERT: So they found that adding fish boosted rice yields by about 25%. It also significantly boosted income and slightly reduced snail numbers. The sample size was kind of small, so that's why they're scaling up the experiment this year. And when I was in Senegal, I got to talk to some of the farmers who'd already tried this out. One farmer, named Abou Diallo told me that it changed his life.
BARBER: Wow. How did it change his life?
LAMBERT: So before, he sold about 60 bags of rice a year. But after adding the fish, he sold about 90 bags a year.
BARBER: Whoa, that's a lot.
LAMBERT: Yeah. And that extra income made a big difference for him.
ABOU DIALLO: [NON-ENGLISH SPEECH]
LAMBERT: He says he's been able to renovate his home and buy a flock of sheep. Plus, he says the fish he gets from his farm taste better than those he gets at the market, and are obviously cheaper too.
BARBER: Wow. OK. So what about this disease, this-- your nickname for it, schisto?
LAMBERT: Yeah. He hasn't gotten it since, but it's hard to say if that's because of the fish or not. That's why the researchers are expanding the scope of the experiment this year, to really try to nail down the precise benefits. Understanding what works and what doesn't will help the researchers scale up this practice even more. They told me that's really their ultimate goal.
BARBER: OK. So, but how would that work? You obviously need a lot more fish.
LAMBERT: Yeah. You would need a lot of fish, and there'd have to be a lot of growth in that aquaculture industry to produce all those fish. And farmers would need a lot help in getting up to speed on how to do this. But Momy thinks the potential is there. In part, she thinks that because this is a particularly Senegalese solution to these problems.
NDAO: You are in Senegal. Senegal, Senegalese people love a lot fish. We eat it every day, rice and fish.
LAMBERT: It's actually the national dish, called thieboudienne.
NDAO: If you grow rice and fish in the same area, you have this, just need to add vegetables. [LAUGHS]
LAMBERT: She says that farmers have been pretty willing to try it out, in part because of that cultural connection. If they can back that up with some science that says it helps prevent schisto and helps them grow more rice and make more money, she thinks it could really take off.
BARBER: Jon, thank you so much for bringing us this reporting.
LAMBERT: Thanks for having me.
BARBER: This episode was produced by Rachel Carlson, Hannah Chinn, and Juan Diego Ramirez. It was edited by our showrunner, Rebecca Ramirez.
LAMBERT: Tyler Jones checked the facts. Jimmy Keeley was the audio engineer. I'm Jonathan Lambert.
BARBER: And I'm Regina Barber. Thank you for listening to Short Wave, the science podcast from NPR.
[RELAXING MUSIC]
BARBER: Did you have some of this national dish?
LAMBERT: I actually did have some thieboudienne, and it was incredible, honestly.
BARBER: Yeah!
LAMBERT: It was so-- it was so good.