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JOE PALCA, host:

From NPR News, this is TALK OF THE NATION: SCIENCE FRIDAY. I'm Joe Palca.

And for the rest of this hour, in case people were wondering, we're going to be talking about fish farming. Eating salmon used to be an expensive luxury. But now at four or five dollars a pound, Atlantic salmon has become a staple at many dinner tables.

According to the Blue Ocean Institute, the Atlantic salmon sold in the United States, almost all the Atlantic salmon sold in the United States, is farmed. Fish farming, especially for salmon, is controversial. Critics of the practice say it has high environmental costs and can cause water pollution and lead to disease in wild fish stocks.

A new report in the journal proceedings of the National Academy of Sciences this week seems to back up that claim. According to the study, juvenile migrating wild salmon are becoming infected by sea lice as they pass salmon farms. The study says the sea lice can sicken and even kill the migrating salmon.

Joining me now to talk more about this study and it's possible impact is my guest Ray Hilborn. He's a professor of aquatic and fishery sciences at the University of Washington. He's also the winner of the 2006 Volvo Environment Prize.

Congratulations, Dr. Hilborn. And thanks for joining us today.

Dr. RAY HILBORN (University of Washington): Thank you very much.

PALCA: So this study, can you tell us a little bit more about how the juvenile salmon were becoming infected and why we should even be concerned about this?

Dr. HILBORN: Well, what the authors of this study did is follow salmon down through the migration through the island network in central British Columbia, where there's many salmon farms, and follow the rate of infection of the salmon by these sea lice. Actually this has work that had already been - they'd already published previously - and showed essentially that when they went by salmon farms, the infection rate of sea lice went up dramatically.

And then they've also showed in this study that if you then took those fish and held them in pens, the ones that were heavily infected by sea lice had a very high mortality rate, suggesting that the salmon farms are generating a lot of sea lice on juvenile salmon and many of them are dying.

PALCA: So what's the possibility that - I mean, do we know that the sea lice are definitely being - the population of sea lice are being increased by the salmon farms?

Dr. HILBORN: No, I don't think we actually know anything about the total population of sea lice, because that's quite hard to measure. But the study definitely provides support for those who argue that the salmon farms are causing more mortality among the wild naturally spawned fish as they move up through these inlets towards the ocean.

PALCA: I should add that if you want to join this conversation about fish farming please call us. Our number is 800-989-8255. That's 800-989-TALK.

Maybe I should get you to describe to us just a little bit about what fish farming is.

Dr. HILBORN: Well, salmon farming as predominantly practiced in Norway, the East Coast of the U.S., a little bit on the West Coast of the U.S., and western Canada, involves raising baby salmon in a hatchery, then putting them out in pens that are what they call net pens that sit in the salt water and feeding them in there until they're ready to market.

So there's no - it's not like a hatchery where fish are let go and go into the wild. These fish are completely contained within the farm's operation unless something goes wrong and the net gets torn.

PALCA: So are these - I mean, what's the concern here? Are they worried that the fish will escape and somehow contaminate the wild population or what?

Dr. HILBORN: That's certainly a concern that many have expressed. But that's not what this article - this article is about these farms basically being a source of these sea lice and that infects wild fish as they swim by. And because the farms are naturally quite high density compared to the natural density of salmon.

PALCA: And what are some of the other arguments against fish farming? I mean it sounds reasonably benign.

Dr. HILBORN: Some of the other arguments - there is others. There's a pollution argument that the areas under farms get a lot of the food that gets uneaten. And there's some effects of farms on a pretty small scale. I think the bigger concern that has received more publicity in the past has been the impact of fish that escaped from farms on wild fish. So for instance, in British Columbia, a lot of the Atlantic salmon that have escaped have now started to spawn naturally, and they've basically become an introduced species, which most people would regard as undesirable.

And in the Atlantic, in the range of Atlantic salmon, their concern is that these fish that are raised in farms are highly bred and highly domesticated, and when they go out and spawn with wild fish, they reduce the viability of the wild population by putting in a lot of genes that are really not designed to do well in the wild.

PALCA: And is that why the state of Alaska has banned fish farming?

Dr. HILBORN: That's one of the reasons. I think the main reason is that salmon farming has dramatically reduced the price of salmon in the world, and that's had a very negative impact on Alaska salmon fisheries. And so in Alaska, salmon farming is viewed as very much a bad competitor with their own industry on healthy wild salmon.

PALCA: Okay, let's take some of your calls now, and let's go to Jeff in Buffalo, New York. Jeff, welcome to the program.

JEFF (Caller): Thank you for taking my call.

PALCA: Sure.

JEFF: As I understand it, most of the salmon farming is conducted in estuaries, river estuaries, and of course salmon that are coming back out, the juvenile smolt come out through the estuaries and are then exposed to the sea lice. Being as they aren't as well equipped with scales, they're much susceptible, is that the case?

Dr. HILBORN: Well, I think most salmon farms are actually not in true estuaries. They're usually in, say - in Norway, they're in fjords. But I think your basic mechanism is probably right, that these are young fish that have just entered the saltwater pretty recently. I'm really not an expert on the defenses of the individual fish to the sea lice.

JEFF: Yeah, as I understand it, Canada has quite a fishery - well, the farmed fishing farm in the estuaries, and it's doing quite a bit of damage to the Atlantic salmon in the Northeast United States due to bleed over populations into the U.S. estuaries as well.

PALCA: All right, Jeff. Thanks for the call. I wonder, Dr. Hilborn, can you tell us a little bit about the part of this field that you are spending most of your time with these days?

Dr. HILBORN: The salmon farming?

PALCA: Well, no, your own research. I mean, are you also looking into the salmon farming issue, or is that just one part of what you're doing?

Dr. HILBORN: Oh, I mean, the salmon farming is not a major part of my own research. I was just asked to comment by the journal on that article.

PALCA: Oh, okay.

Dr. HILBORN: But I would like to mention that one of the counterarguments to this article is that there are - and there's at least one paper out documenting this - that the wild salmon have done particularly well in certain years, despite these farms there. And the paper made no attempt to estimate the population level impact. And that's still an issue that is to be resolved. Yes, okay, fish swimming by farms get infected and they die, but is this is an important issue at the level of the wild populations of B.C., and that certainly is not a settled issue.

PALCA: Okay. Let's go now to Dan in Syracuse, New York. Welcome to the program, Dan.

DAN (Caller): Yeah, I was trying to pull over. Your screener told me I had a little bit of background noise. I was speaking in Bluetooth, but I'm trying to pull over as fast as I can to talk.

PALCA: Okay.

DAN: The only question I have, as I told her, that you know, we're talking about a red flag on our food products, but I guess with a lot of the salmon, it may be a pink flag. I guess the question I would have, I'll just make it simple and I'll listen off the air, is what salmon should we be eating? What is the safest, and can we get that out so that the public will understand what that means?

PALCA: Okay, thanks, Dan. Ray Hilborn, can you speak to that at all?

Dr. HILBORN: Well, certainly, I don't think that there is any - the top of the list would have to be wild salmon from healthy populations, which basically means Alaska and some parts of British Columbia, that they're - you know, I don't think there are any concerns about conservation, pollutants, etcetera. You know, most of the world's farmed salmon come from areas where you don't have much in the way of wild fish anymore - Chile, for instance, it's all a completely artificial industry.

So you know, there's a lot of judgment calls as to what you consider acceptable. And you know, certainly I've had a lot of farmed salmon that was an extremely good product. I wouldn't say that people shouldn't eat farmed salmon. But this is certainly from the point of view of management of populations. This is a warning that we have to be very careful, and we really need to decide if we want to have salmon farming in places where we have healthy wild populations.

PALCA: Now this paper's talking about these net pen aquacultures, but are there other types that might be more or less susceptible to this problem?

Dr. HILBORN: Well, many environmental groups have pushed for salmon farms to move onto dry land, where they raise the fish in tanks rather than in open net pens, which would essentially eliminate almost all of these concerns, because they could treat the effluent, they could treat any pollution issues. But my understanding is that that is just economically much more expensive and not economically viable at the moment.

PALCA: So getting to that point. I mean, is a lot of this being driven by the fact that people are just expecting to pay less and less and less for food? Is that what's driving these attempts to farm fish more inexpensively?

Dr. HILBORN: Well, the Norwegians developed this salmon farming technology and, you know, it's been astoundingly successful at producing a lot of fish at a very low price, and it's being copied anywhere in the world that people could have the right kind of habitat. And it's just the natural dynamic. If you can produce something you can get a lot of money for at a reasonable cost, someone's going to do it.

PALCA: All right. We're talking with Ray Hilborn. He's a professor of aquatic and fishery sciences at the University of Washington. I'm Joe Palca, and this is TALK OF THE NATION from NPR News.

And let's take another call now. Let's go to Scott in Cincinnati, Ohio. Scott, welcome to the program.

SCOTT (Caller): Thank you. My question concerns more of the product that the fish are fed in the aquaculture pens, the red food dye in the pellets that causes the salmon to become more pink and, I guess, be more commercially viable. And I buy quite a bit of it from my wholesale club, and I've seen it also in the grocery stores.

I called and asked about it. It was not approved by the FDA, and I'm wondering if that red dye that's in the pellets that's fed to the salmon in the aquaculture pens, is it cancer causing? Has there been any research done on that? And then also I was curious about is the omega-3 count in the aquacultured salmon as high as natural salmon caught in the wild that we would eat. Thank you.

PALCA: Okay, two question there, red dye and omega-3. Can you speak to either of those, Dr. Hilborn?

Dr. HILBORN: No, I'm afraid I'm going to have to pass on both of those. I'm an ecologist, and those are physiological type questions. I just don't know the answer to either of those.

PALCA: But I mean, just from an ecological standpoint, you said that the problems would be solved if some of these ocean aquacultures if things were kept in tanks. I presume the tanks would be on land. Are there no environmental issues related to tanks - fish on land?

Dr. HILBORN: Well, I think - not that I know of.

PALCA: Okay.

Dr. HILBORN: I mean, there would be - the only obvious one would be you would have the effluent, you know, that the water would need to be recycled and it would contain a high level of nutrients because of both the fish excretion and the unused food, and it would probably still have disease issues. I mean, I don't know, you know, if you could filter out the larvae of the sea lice, etcetera.

PALCA: Okay, I think we have time for one more call. Let's go to Leslie in Kansas City, Missouri. Welcome to the program.

LESLIE (Caller): Yes hi. Thanks, it's quite interesting. I was disturbed, though. I don't know if you've mentioned the fact that these farmed fish are often treated with antibiotics. Is that correct? I've read that that's the case because they're in such close confinement, just like in beef cattle. They use it as a prophylactic type thing.

PALCA: Ray Hilborn, what -

Dr. HILBORN: Certainly there is some treatment with antibiotics. The data I've seen suggested that due to concern about that, the amount of antibiotics being used has been reduced about a hundred fold.

LESLIE: Really.

Dr. HILBORN: I've seen one paper on that, but that was an issue that was raised a couple years ago and again, they've responded to that pretty rapidly. So in terms of the actual total level of average treatment, I'm not sure, but it's a lot less than it used to be.

PALCA: Leslie.

LESLIE: Well, that's good because you talk about, you know, these things are relatively harmless, or some people say, but I don't believe that's the truth. We've got enough antibiotics in our world - in the groundwater and everywhere else.

PALCA: Okay. Leslie, thanks very much for the call. And just briefly, we only have about a minute left, but tell us a little bit about the reason for your winning the Volvo Environment Prize.

Dr. HILBORN: Well, my main area of research has been on trying to figure out how to sustainably manage world's fisheries, and my particular interest has been in rather than decrying all the failures, of which there have been many, is looking at the places that fisheries have been successfully managed and trying to apply the lessons from successful fisheries to all the ones that haven't been successful.

PALCA: And you think there - I mean, obviously you're optimistic about the possibility of applying these lessons.

Dr. HILBORN: Oh yeah. I think, you know, we know very well how to manage fisheries successfully and sustainably now, it's just that we - there's a lot of impediments to doing it, ranging from legal impediments to fixed interests, etcetera. But you know, we've learned a lot of lessons, and we know how to do it.

And you know, the track record in the U.S. is remarkably good. I mean, the U.S. only loses about 15 percent of its potential yield due to over fishing. You know, we're getting 85 percent, and I defy you to find another government program that produces 85 percent of a theoretical maximum.

PALCA: Well, I think I won't take up that challenge, but instead I'll thank you very much for joining me this hour.

Dr. HILBORN: Okay, thank you.

PALCA: Okay. That was Ray Hilborn. He's a professor of aquatic and fishery sciences at the University of Washington.

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