KPBS Radio is undergoing scheduled upgrade work which may result in temporary signal outages.
Garbage Patch Study Finds Plastic In Pacific Ocean Fish
Monday, July 18, 2011
On a recent expedition to the North Pacific Ocean UC San Diego researchers discovered plastic in nearly 10% of the fish they found. The Great Pacific Garbage Patch is to blame.
It is an area about 1,000 miles west of California that has collected a huge concentration of debris and plastic as a result from ocean currents. Based on evidence of the study, researchers estimate that fish in the ocean of the North Pacific consume plastic at a rate of roughly 12,000 to 24,000 tons per year. We talk to researchers at Scripps Institution of Oceanography about the recent findings on the Texas-sized Garbage patch and its impact on the environment.
Pete Davison, Scripps graduate researcher
Jim Leichter, Associate Professor of Biological Oceanography at Scripps Institution of Oceanography
Transcript DisclaimerThis is a rush transcript created by a contractor for KPBS to improve accessibility for the deaf and hard-of-hearing. Please refer to the media file as the formal record of this interview. Opinions expressed by guests during interviews reflect the guest’s individual views and do not necessarily represent those of KPBS staff, members or its sponsors.
CAVANAUGH: San Diego researchers went on a scientific mission in 2009 to explore the great Pacific garbage patch. We spoke to several of the grew at that time to find out what they were seeing in this area of dense plastic accumulation about a this happened miles west of California. Now those researchers have released disturbing findings finding that some of that plastic garbage is winding up in the stomachs of fish. My guest is Jim Leichter, Associate Professor of Biological Oceanography at Scripps Institution of Oceanography. And Jim, hello.
LEICHTER: Hello, Maureen. Thanks very having us.
CAVANAUGH: And Pete Davidson is in studio with me. He's a Scripps graduate researcher, peat, hello.
CAVANAUGH: Let me start with you, Jim. What kinds of specimens did you collect from the garbage patch?
LEICHTER: Well, we collected a wide range of mostly surface, but also subsurface biological and physical samples. Essentially net filtering water and seeing what's in this, particularly small materials.
CAVANAUGH: And Pete, you also collected fish right?
DAVIDSON: Yes. And this would be the subsurface net that Jim was talking about.
CAVANAUGH: What kinds of fish?
DAVIDSON: Well, the fishes that I was collecting were mostly what we call mesopelagic fish. And these fish live maybe 5 or 600†yards down in the water column in the day, and at night, they come up to the surface to feed.
CAVANAUGH: I see. So we wouldn't necessarily eat this species of fish.
DAVIDSON: I'm told my taste bad.
CAVANAUGH: Okay. All right. Just wanted to get it out of the way. Jim, as I said, this scientific mission took place in 2009. The first big findings are coming out now. What did you do in the mean time? What did you do with these specimens that you collected?
LEICHTER: Well one of the things, the cruise that we did, it's not the first trip that people have done out there, but it was the first of its type. It was organized by and run by graduate students. So what's been happening since then is that Pete and other folks on the crews have been working quite hard on taking all of the samples and really processing them into data. So in that case, dissecting fish and in other cases painstakingly counting all the small amounts of material that are in those samples.
CAVANAUGH: The big headline that's come out of this first scientific release from this study that you -- the mission that you went on in 2009 is that there is plastic, you found plastic inside the stomachs of the fish specimens. Tell us about that.
DAVIDSON: Well, in essence, that's true. We took all these specimens from our nets and cut them open, these are specimens about the size of your finger. Three inches long or four inches long. And you open it up and we rinsed out the inside of the stomach into some water, then we filtered that. And we looked at it under the microscope, and we found little itty bits of plastic, and they came in little films or fragments, fibers, bits of rope fiber, fishing line. And most the ones, since we were looking at small fish, the fragment accident we found were microscopic, which is one of the reasons it takes a while.
CAVANAUGH: Is there any idea, Pete, that the fish, if the natural process had been allowed to continue, would perhaps have excreted that plastic?
DAVIDSON: It's possible. We don't know. I'm not sure how to measure that. Other than keeping them in an aquarium and seeing what comes out. But yes, we don't know if -- they throw it back out the mouth, or they poop it through. It's possible they might just clog up and die. We don't know these things.
CAVANAUGH: I see. All you found was in fact indeed the fish had been eating small pieces of plastic. Jim, let me ask you, to give us a little bit of the history of this garbage patch, for people who may not be familiar with what it is we're talking about, how did all of this garbage, I guess most of it plastic, end up in the middle of the Pacific ocean?
LEICHTER: Yes. It's a long way off shore. The area that we were studying is even more than a thousand miles off of California. So it takes several days to get out there even by ship. The material we think, and other people have looked at this, it's accumulating material features of the circulation, of the currents which air large essential clockwise circulation around the north Pacific. And what's happening is that buoyant material that could be coming from almost anywhere along the Pacific rim, that material -- or it could be starting in the ocean if it's thrown off of ships, that material is accumulating in a very large zone. You can think be of it, if drew a triangle from Hawaii over to California, and then up north quite a considerable distance, a large portion of the ocean is oceanographically such that it's a site of what we call convergence. And the plastic material seems to be collecting. There are a lot of things we don't know. We really don't know how much. We don't know how long this has been going on. But we do know that -- we're pretty sure that there's significantly more material now, for example, than there was a decade ago or two decades ago. And the sources are variable, and I think can include any of the major sources of trash or debris or waste materials entering the ocean.
CAVANAUGH: Jim, you've explained that this whole research project going out to what's called the great Pacific garbage patch was a bit of an emotional experience for everyone on the boat. Tell us about that.
LEICHTER: I think it really is. And that's one of the things I think to sort of get across to people hearing about this story, there were several. On one we went out there, having heard that this was going on, but as scientists having a healthy dose of either skepticism oh, well, let's see. So one of the first emotions that I experienced and noticed others in the group was surprise at the amount of material we were finding. And then I think moving from surprise into a real sense of sort of the astonishing scale the -- what you might call the human footprint out there in this very remote part of the ocean.
CAVANAUGH: Pete, talk to us a little bit about that. That feeling that, you know, you've heard about it, but there it is. Of there it is just sitting there.
DAVIDSON: Well, it's -- I you sail out there, it's beautiful, it's sunny, it's nice. And every few minutes or so, you see a plastic bottle or bucket or a laundry basket go by. But if you look really closely at the water in just about every square yard of surface, you see these little flecks of plastic floating. And they're about the size of your finger nail. So if you look off the side of the bolt, and you're looking down this, and it's everywhere. . And the ocean is so big that if you take the concentration of plastic you see in those few square yards and you multiply it out by the area that this covers, it's an immense amount of debris. And -- but you can't see it from space, you can't stand on it.
CAVANAUGH: Right. It's not like a mound in the Pacific ocean. It's just this wide area, I've heard, the size of the state of Texas or something.
DAVIDSON: It's much bigger than Texas. I checked this out.
CAVANAUGH: That's filled with this plastic debris. I have also read that most of the plastic is actually dissolved into the ocean. Do we know that?
DAVIDSON: I don't think the plastic necessarily dissolves, per se, speaking scientifically. What happens is that wind and waves and sun break it down into smaller and smaller wits. So the little fragments we're finding in the fish were not what was made in the factory. They're little bits that have broken off. If you leave a plastic glass on your back porch for a year in the sun, it's going to crack apart and fall apart. Those are the little bits we're seeing floating around there. So they don't say made in USA, made in Japan or whatever. But they're blue or green or white, and the fish, eating them. And one of the things you might think about is, so what? It could be that there's no harm to them. But we do know, there have been studies that have shown that toxins prefer to absorb onto the surface of these plastic than they prefer to be in the water. So these are hydrophobic. So the plastic bits are floating around in the water, and things like DDT are sticking to the surface. So it's possible when the fish eat them, they're absorbing some of those toxins that come from air pollution. And this is something that I think should be looked into.
CAVANAUGH: That is absorbed more readily by this plastic debris than it would be just the water itself.
DAVIDSON: Right. If you think of it as oil and water don't like to mix, these DDTs are hydrophobic, they don't like to mix with water. So it's possible when the fish are eating these little bits, they're getting essentially poisoned.
CAVANAUGH: I'm speaking with Pete Davidson, he's a Scripps graduate researcher, and Jim Leitner is. We're talking about the initial scientific findings that have come in from the great Pacific garbage patch voyage that these researchers took back in 2009. And we've been talking about the fact that you found little bits of plastic in fish specimens that you collected from that region. How many specimens?
DAVIDSON: A little over 9%, and that works out to a lot of fish. These are very common fish. They're the most abundant vertebrates on earth by weight. And there are several of them for every square yard of ocean surface. So if you take 9% of them, and you weigh the little bits of plastic in their stomach, and you multiply it all out. You get an annual consumption rate of potentially 12 to 24,000†tons a year.
CAVANAUGH: Do we know if the fish are actually ingesting the plastic themselves or are they getting it from what they feed it?
DAVIDSON: I doubt they're getting it from what they feed on. They feed on very small crustaceans and also krill. It's possible the krill and cocoa pods are eating this, but given the size of the plastic parts we found, we think the fish are just pecking them. They see it floating in the water and they peck just like a fish in your fish tank.
CAVANAUGH: Where are these fish that have little bits of plastic in the food chain?
DAVIDSON: Trophic level three. If you think of a plant as trophic level one, they get their energy from the sun and create their own food, and then trophic level two would be an herbivore, somebody who eats plants like a cow or a sheep. And the next trophic level, would be these fishes. It's well short of a tuna which would be a top carnivore like a whale or dolphin or us. But they're midtrophic level animals.
CAVANAUGH: Would the tuna be eating these fishes?
DAVIDSON: Some of them. Maybe five% of the diet of the tuna is these fish. So it's possible.
CAVANAUGH: I see. And it swims back home, as it were.
CAVANAUGH: Jim, what impact does, if any, does the garbage patch have on San Diegans?
LEICHTER: That's an excellent question, Maureen. Of I think the combination -- there is a direct impact, certainly, as San Diegans we're all very closely connected to the sea. We look out and we see it all the time. Soap there's certainly the sense of are we living as a clean ocean? Are we living as an ocean heavily impacted by people? There's -- with us discuss material getting into the food wagon potentially. And then I think I would say that third is the sort of the less tangible, but the sense that we really are connected to the Oceanside, not just in terms of what we take from it, but what we're -- in a lot of sense are putting into the ocean. And I think that sense that the human impacts on the ocean are large enough to cover or to impact various far, far from shore small fish in the food web that a lot of people wouldn't even necessarily think or know about it. So I think this illustrates a -- the type of impact we're having in the ocean and that can attend to the coast as well.
MAUREEN CAVANAUGH: I'm going to direct this to you, Pete. Because Jim sounds like he's still at the great Pacific garbage patch with the lines that we have. But what research remains to be done on the specimens that you collected?
DAVIDSON: On the ones that I select collected? I think I'm done. There were other people out there besides me. There was a researcher, the chief scientist, a grad student, and she is studying the distribution of the plastic, she's studying whether or not it's associated -- it's changing the tab at that time in certain ways. So I think she's found a link been this marine inspect, and this plastic. So the in fact that there's more floating material, means the insect has a higher population level than it would. So that's an. Example of an ecological change. I believe she's working that up now. It takes a couple years to write up science. Science is not fast.
CAVANAUGH: Exactly, but we're going to be hearing things from this research project for a number of more years. I want to thank you very much, Pete Davidson, Scripps graduate researcher, thank you.
DAVIDSON: Thank you.
CAVANAUGH: And Jim Leichter, associate professor of biological oceanography at Scripps. Thank you.
LEICHTER: Thank you, Maureen, and thank you for the interest in this topic.
To view PDF documents, Download Acrobat Reader.