Why Native Fish Matter

IRA FLATOW: And now we turn the page back to our book club. As we announced last week, we’re setting sail for the lakes, the Great Lakes– Ontario, Erie, Huron, Michigan, and Superior. HOMES, as we call them, and as we read Dan Egan’s The Death and Life of the Great Lakes, you can learn how to participate on our website at sciencefriday.com/bookclub. Producer Christie Taylor is captaining the ship, and is back with us for an update. Welcome back, Christie.

CHRISTIE TAYLOR: Thanks, Ira. I still remember learning about HOMES in grade school too.

IRA FLATOW: Wisconsinite that you are, we should let everybody know.

CHRISTIE TAYLOR: Yeah, exactly. In my blood. As you said, we’re celebrating the Great Lakes this month, and they have been through a lot, as you’ll know if you’ve been reading the book– pollution, invasive species, low water, and now high water– but there are also places that a lot of people love. Our guest reader, biologist Donna Kashian, shared this memory of a butterfly migration.

DONNA KASHIAN: I have so many wonderful memories of the Great Lakes, both as a child whose parents had a cabin near Lake Michigan and as an adult doing research on the lakes, but one in particular stands out. I was doing research on Lake Huron. I don’t even remember what we were looking at on that particular day. It was late in the season– maybe August– we were in the middle of the lake. It was flat water, clear blue skies, and monarch butterflies were just flying everywhere. We were in the middle of their migration south. It was so surreal and beautiful. I knew birds used the lake as a flyway on their migration, but I never knew monarchs did.

CHRISTIE TAYLOR: And our other guest reader, journalist and author Peter Annin, had a particular summer night that he still looks back on.

PETER ANNIN: My wife and I are fortunate to live on a remote section of Lake Superior’s shoreline, and on a summer night a few years ago, we paddled to dinner at a friend’s house about a mile away. After a delicious fireside meal on the beach, we launched for home into a calm, cloudless, moonless night with the Milky Way splashed brilliantly across the sky. As we paddled along that dark, uninhabited shoreline, it was as if we were traveling through a snow globe of stars reflecting off the water and sky all around us. No one spoke. We just silently slipped along, with no lights or sound except for the gentle dips of our paddles in Superior’s deep, mysterious water.

CHRISTIE TAYLOR: Hm. Beautiful. And our listeners have also been sharing their fond memories on the Science Friday VoxPop app– like Robin, who now lives in Baltimore.

SPEAKER 1: My absolute favorite memory is taking the car ferry from Ludington to Manitowoc across the lake. It was the most incredible experience being at– it felt like you were in the middle of the ocean. It made you realize just how big Lake Michigan really was.

CHRISTIE TAYLOR: And now I want to talk about fish. There are more than 100 species that make their living in the waters of the lakes. They thrived in the glacier-fed waters for millennia before humans connected the lakes to the sea, bringing in new fish and other pests. And now, another invasive fish– three different species actually, of carp– are threatening to enter the lakes from Illinois.

But the native fish are still there, struggling in places, but alive– and our next guest says that, while helping those native fish to thrive won’t restore the lakes to their former state necessarily, it will make them more resilient to the new dangers of carp, climate change, and more. And here to explain is Dr. Solomon David, a fish ecologist and assistant professor of biology at Nichols State University in Thibodaux, Louisiana. Welcome, Dr. David.

SOLOMON DAVID: Thanks, Christy. Happy to be here.

CHRISTIE TAYLOR: Yeah, and I can’t see you right now, but I hear that you have a fish in the studio with you right now.

SOLOMON DAVID: I do. I try to have a gar on hand at all times.

CHRISTIE TAYLOR: So wherever you go, there you gar?

SOLOMON DAVID: Exactly.

CHRISTIE TAYLOR: Well, thank you for bringing a prop today. One of the reasons we wanted to talk to you is because our last book club this summer was about birds, and how smart they are, and how great and beautiful and pretty, and it turns out that there’s kind of this science battle between bird people and fish people. The scales are really flying. Why is this making such a splash?

SOLOMON DAVID: I think a battle is a– that’s a great way to put it, but I think we should emphasize that it’s a friendly back and forth of scientists showing off the overall diversity, and in the end that fishes are a lot cooler than birds.

CHRISTIE TAYLOR: Oh– see, oh. OK. So why do you love fish? Why are fish cooler than birds for you?

SOLOMON DAVID: I think it’s the diversity. You’ve got a high degree of species diversity, there’s more species of fish, there’s more individuals of fish. They can change color– again, they’re extremely adaptive and resilient and diverse as vertebrates, but in the end, birds and fish, they’re all fish.

CHRISTIE TAYLOR: They’re all fish? How is that?

SOLOMON DAVID: So if we think about the tree of life, all the vertebrates are on a particular branch, and fishes, certain types of fishes, branched off, and then birds went another direction. But really, when we think about it scientifically speaking, they’re all part of the same group that we would actually call fish.

CHRISTIE TAYLOR: So everyone likes to say that birds are dinosaurs, or dinosaurs are birds. Does this mean dinosaurs are also fish?

SOLOMON DAVID: Exactly. So I mean, the bird people like to say that birds are cool because they’re dinosaurs, but really they’re all fish, and so I think it shows that we can all get along, and think that biodiversity is really cool.

CHRISTIE TAYLOR: We all love fish, when it comes down to it.

SOLOMON DAVID: Exactly.

CHRISTIE TAYLOR: Great. Well, you’ve done a lot of research on the Great Lakes, which is where our book club is focusing this month. We’ve already talked about the invasive species last week that are changing the ecosystems in the lakes– the alewives, the lampreys, the mussels– but what about the good guys, the native fish? Who’s who, and how are they doing?

SOLOMON DAVID: Yes, I think it’s important to talk about the positive stories of the Great Lakes. So we’ve got some Great Lakes native species, like the lake sturgeon. It’s a species that’s charismatic– they grow really large, they can get over six feet long. They’ve actually had a makeover. They were once hated fish, and now they’re a respected flagship species of the Great Lakes. So that’s one of our charismatic species that we have in the Great Lakes, where their populations are starting to come back with some help from us.

Some other species, like the lake whitefish, which are cousins to salmon, we’re seeing migrations return after a hiatus of about 100 years, so–

CHRISTIE TAYLOR: Wow.

SOLOMON DAVID: That’s environmental improvement, habitat improvement. We’ve got that species starting to come back.

CHRISTIE TAYLOR: What about– so when we talk about the fish that are starting to come back, what makes a fish species more resilient than others? And are all the native species doing about the same, or are some of them more sensitive and still struggling?

SOLOMON DAVID: Great question. It’s extremely species specific, so particular types of fish require particular environmental parameters, particular things to eat. So if particular habitats are improved, then it might draw back maybe a couple of different species of fish, maybe one in particular. In other cases, if we can improve habitat, we can bring back entire fish communities.

CHRISTIE TAYLOR: Really. So what is improving habitat, then? Is that getting rid of pollution? Is there anything else they need?

SOLOMON DAVID: I think improving the habitat by getting rid of pollution, but also restoring habitat. So an example from Green Bay, Wisconsin, where we built a wetlands– we restored wetlands and created some artificial wetlands– the fish came. So it’s sort of an if you build it, they will come perspective.

CHRISTIE TAYLOR: Nice. Well there’s another fish that’s ambiguous when we talk about native versus invasive, and that’s the introduced Pacific salmon, which was added on purpose to the lake, but is not from there. Should we call those invasive, or do we care about their health? Do we want them there?

SOLOMON DAVID: Well, human categories are always kind of fun. So we call the bad guys invasive and the good guys are sort of introduced. So I think they’re important to the economy, to recreational fisheries, but they do affect the ecosystem, so I think it’s important to keep that in mind, and hopefully maintain balance between our introduced valuable fishes and our native species.

CHRISTIE TAYLOR: And then there’s– you mentioned you brought a gar with you to the studio, and we haven’t talked about gar yet. What is a gar, Solomon?

SOLOMON DAVID: So if I were to describe a gar, I’d say picture an alligator with fins instead of legs. They’ve got a long snout, lots of teeth, armored scales. It looks, again, like a crocodile with fins instead of legs. It’s a very ancient-looking fish.

CHRISTIE TAYLOR: And they are really ancient, right? They’re older than any other fish, or something like that?

SOLOMON DAVID: Yep. They’ve been around since about 150 million years, so they’re older than a Tyrannosaurus Rex.

CHRISTIE TAYLOR: Wow. Why? What’s the secret to their success?

SOLOMON DAVID: I think they’ve been able to adapt to their habitats really well. They’re air breathing, so they can go up for air, they can survive in habitats that maybe more conventional water-breathing fishes can’t, but they’re really just persistent. They’ve found a body plan that works, and they’ve stuck with it for, you know, since the Jurassic.

CHRISTIE TAYLOR: If it ain’t broke, don’t fish it?

SOLOMON DAVID: Exactly.

CHRISTIE TAYLOR: I just made Ira make a face on the other side of the room. So gar are important partly because they are also a native fish in the Great Lakes, but they’re not just there, right? They’re in Louisiana, which is where you are. How many different kinds of gar are we talking about?

SOLOMON DAVID: So there’s seven species of gars that are alive today. They range from southern Canada all the way down to Costa Rica, and like you said, we’ve got Great Lakes gars that some of those same species exist down here in Louisiana throughout the Mississippi River Basin.

CHRISTIE TAYLOR: So what makes them the fish that you have chosen to study?

SOLOMON DAVID: I think they’re really cool. I was into dinosaurs as a kid– that’s not a nod to birds– but I think I like the look of them, the sort of ancient appearance, and they’re very persistent, so they’re very resilient. So I think when we think about biodiversity and resilience, this is a great example of a resilient organism that has persisted for a long time amidst a lot of other sort of changes since 150 million years ago.

CHRISTIE TAYLOR: Just pausing to say that this is Science Friday from WNYC– I’m Christie Taylor. This is Science Friday from WNYC Studios. Talking about fish with Dr. Solomon David, assistant professor of biology at Nichols State University. And Dr. David, you are also looking at using gar for medical research, which is kind of confusing to me because I know we have zebrafish as a model organism already, so why do we need another fish model?

SOLOMON DAVID: Sure– that’s a great question, Christie. We’re helping out some biomedical research, so we’re sort of the boots on the ground working with some of these fish. So the zebrafish works as kind of a lab rat fish, if you will. We use the zebrafish to understand the human genome and human disease. The gar, since it sort of has this go-between between the zebrafish and the human genome, so the gar genome actually helps us understand the human genome better by sort of translating what we know about the zebrafish. So it kind of works as a Rosetta Stone, if you will to translate it, and the more we know about the human genome the more we can predict diseases, development, that sort of thing. So they’re important to ecosystems, but they can also be very important to us.

CHRISTIE TAYLOR: Because we’re also fish, apparently.

SOLOMON DAVID: Exactly.

CHRISTIE TAYLOR: I’m not quite going to get over that, I think. So going back to the Great Lakes, one of the species of gar is this giant monster called the alligator gar which, in recent years, the state of Illinois has been trying to restore to their historic range in Illinois. Is this a move that could help the Great Lakes invasive species problem at all?

SOLOMON DAVID: Well, I think it’s important to recognize the alligator gar found in the Great Lakes, but they’re almost gatekeepers if you will. Maybe they could be the gar-dians of the Great Lakes, if you will. But they’re apex predators, but they won’t really be able to put too much of a dent in the Asian carp problem. So they’re important for increasing biodiversity. They will eat Asian carp, but there’s just so many that it’s not going to– it may not make appreciable differences there.

CHRISTIE TAYLOR: But biodiversity has its own value in helping an ecosystem be resilient.

SOLOMON DAVID: Exactly, so the more species we have, the more resistant and the more resilient we can be in the face of threats such as habitat loss invasive species, which are going to be exacerbated by climate change.

CHRISTIE TAYLOR: OK. So what if I told you I’m still perhaps a bit on team bird right now, for all the great things you’ve said about fish? what would you say to help people like me appreciate fish when we can’t necessarily just hang out in a lake in a scuba tank watching them go by every day?

SOLOMON DAVID: Sure. I think it’s important to get into nature. I mean, birders still go out into the woods and look at birds, and so I think if you can get out to a stream, a pond, or a lake, rivers, bayous, that’s what I did, and that’s what got me into fish, but also a lot of other wildlife. Urban landscapes can also have fishes. There are several towns that have waterways going through them. And if you can’t do that, check out local aquariums and zoos. They do great work, and you can see some exotic species and native species that you may not be able to in your backyard.

CHRISTIE TAYLOR: Are there any things fish can do that other animals can’t that just kind of blow your mind?

SOLOMON DAVID: I mean, there’s a lot of cool things that fish can do. I’m not saying no animals can do them, but something like the lungfish can undergo something called aestivation, which is kind of like hibernation. They can go in a sort of suspended animation for six years. So out of the water, they can dry out. You add water, they come back. Fish like the Greenland shark, my favorite shark species, can live up to 400 years old. And they’re also personable, so they can respond to owners, if you have a fish. And so I think they don’t get as much credit as they deserve.

IRA FLATOW: Wow.

CHRISTIE TAYLOR: Yeah. That’s amazing.

IRA FLATOW: One last question to Dr. David– is there something, is there an oceangoing gar?

SOLOMON DAVID: There is not necessarily, but alligator gars and longnose gars can survive in the ocean, so you can see them in saltwater.

IRA FLATOW: So they would be called a sea-gar?

CHRISTIE TAYLOR: Oh, no.

SOLOMON DAVID: Exactly.

IRA FLATOW: I’m sorry.

SOLOMON DAVID: I think that’s great.

IRA FLATOW: You guys were going great with the puns. I couldn’t be out-punned. You had–

CHRISTIE TAYLOR: It’s like Ira catnip. All right.

SOLOMON DAVID: That was a great setup.

CHRISTIE TAYLOR: We’re out of time.

SOLOMON DAVID: I went for it.

CHRISTIE TAYLOR: Thank you so much. Solomon David, fish ecologist, assistant professor of biology and gar pun aficionado at Nichols State University in Thibodaux, Louisiana. Thanks to him and his gar guest.

IRA FLATOW: That was great.

SOLOMON DAVID: Thank you so much, Christie.

IRA FLATOW: Christie Taylor runs the Science Friday Book Club, and you can grab a copy of The Death and Life of the Great Lakes, and learn how to participate on our website at sciencefriday.com/bookclub. And if you have any of your own gar puns, send them– you know, tweet them to us @scifri. We’d love to hear all your gar puns, because we ran out of time.

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