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Public Radio's Environmental News Magazine (follow us on Google News)

Super Salmon

Air Date: Week of

Living On Earth’s Diane Toomey reports on the development of the first genetically altered farm-raised salmon. Creators of this "super fish" say it is safe, but critics say that's an open question.


CURWOOD: This is Living on Earth. I'm Steve Curwood. The debate over genetically-modified food is about to enter a new and possibly more contentious phase. So far the dispute is centered on splicing the genes of crops, such as corn or soybeans. But scientists are now experimenting with fish, hoping to speed up the time it takes salmon to fatten up in fish farms. U.S. and Canadian researchers are about to seek government approval for their creation, which could become the first genetically-altered animal to wind up in your local supermarket. Living on Earth's Diane Toomey reports.

(Water flows)

TOOMEY: There's a Quanset hut in Canada that's about to become the newest battleground in the fight over genetically-modified food. To look at it, you wouldn't think that groundbreaking research goes on here. This facility, which sits next to a potato field on Prince Edward Island, is filled with simple motors, fans, and water pumps, and there are three dozen concrete tanks covered with black netting.


TOOMEY: Fish physiologist Arnie Sutterland says some of the salmon here are normal.

SUTTERLAND: Now, these are Atlantic salmon. They're about four years old, and they just spawned last month.

TOOMEY: But one tank over, there are salmon who have undergone genetic engineering.

SUTTERLAND: These fish are about the same size as the tank you just looked at, but they're a year younger, because of their rapid growth rates.

TOOMEY: These are super salmon. They look normal. They don't get any bigger than normal salmon. They just grow faster. A genetically-modified salmon is ready for cooking a full year earlier than normal fish. This transformation is brought about by manipulating the amount of growth hormone a salmon produces. To do that, scientists have been cutting and pasting fish genes together. Elliot Entis heads the company that mastered the technique.

ENTIS: We've taken a portion of a gene from another edible species of fish, either a winter flounder or a fish called an ocean pout, and the portion of the gene which we've taken from those fish is the portion called the promoter sequence. That is, it's the instruction sequence which tells the rest of the gene where to produce a protein, and how often to produce it. We've taken that promoter, that instruction set, instead, and stitched it to the salmon's growth hormone gene.

TOOMEY: By injecting this engineered gene into salmon eggs, researchers have increased the level of growth hormone the fish generate. They put on weight faster and actually use less food to do it.

ENTIS: Our fish appear to need about 20 to 25 percent less feed input to convert to a pound of weight. In other words, our food conversion ratio is somewhere on the order of 20 to 25 percent better or more efficient than that of salmon currently being raised.

TOOMEY: The fast growing fish are called the Aqua Advantage Salmon, and Mr. Entis portrays them as good news for an industry that's notoriously inefficient. Farm-raised salmon normally must eat three pounds of food to put on a single pound of weight. Mr. Entis says he'll improve that ratio. Of course, genetic engineering is highly controversial, but Elliot Entis says this feed is different. He's not mixing genes from totally unrelated species. This is a fish-to-fish transfer, and the alteration involves just one gene that affects just one hormone. He denies he's fiddling too much with Mother Nature.

ENTIS: I'd like to say it's the natural transgenic.

TOOMEY: Critics, though, flatly reject the notion that any genetic engineering is natural.

KING: These glib statements that we're only introducing one gene, that we know what the gene is, we know what the protein is, really misrepresent, you know, what we understand about organisms and all that we don't understand.

TOOMEY: Jonathan King is a molecular biologist at MIT. He's not opposed outright to genetically-modified salmon, but he is concerned that the risks are being downplayed. Dr. King says genetically-modified animals might affect the people who eat them in ways we can't predict.

KING: When you're introducing a new gene, the product of that gene is interacting with hundreds or thousands of other components in the cell. The effects may be, you know, very, very small and hard to detect. The effects may be enormous.

TOOMEY: It will be up to the FDA to pass judgment on the safety of transgenic salmon. The agency will not only look for any impacts on human health, but for the first time will consider the risk a genetically-engineered animal might pose to the natural environment. One risk involves super salmon escaping into open waters. The fear is they could reproduce and pollute the gene pool of wild stocks of salmon. Fish physiologist Arnie Sutterland has been testing a special procedure on Prince Edward Island to make sure that doesn't happen. It involves pressure-shocking the fish before they're even born. The fertilized eggs are placed in a metal container that looks something like a thermos.

SUTTERLAND: And we just fill it full of eggs, raise the pressure up to 10,000 PSI, thereabouts, and hold it there for five minutes, and take the eggs out. And that's it.

TOOMEY: The eggs will go on to hatch, but Dr. Sutterland says those fish will not be able to reproduce. It's not certain if the process can be 100 percent effective. And there's a second risk if the fish escape. Even if they can't reproduce in the wild, will these super-hungry salmon outcompete their wild cousins for food? Dr. Sutterland says that shouldn't be a problem.

SUTTERLAND: They have to feed much more often. And as a result, they're foraging most of the time. Even if they could find enough food in the wild to satisfy this appetite, the risks they're going to have to take will expose them to all kinds of excess levels of predation.

WEBER: Well, maybe they would like to place a good bet on that, because if it doesn't happen, who is really going to be paying the price?

TOOMEY: Mike Weber is a marine policy consultant and former assistant to the head of the National Marine Fisheries Service.

WEBER: As we've seen in any number of cases, salmon that are introduced from hatcheries from farms oftentimes, because of their different behavior, end up displacing wild salmon despite all the assurances that are always made beforehand that it can't happen here.

(Flowing water)

MAN: Go to six point four, that's the length. The weight is four seven five point five.

TOOMEY: The debate over genetically-modified salmon is just beginning. As it unfolds, scientists here are continuing their research, measuring just how quickly these fish can grow. Even if they gain FDA approval, it's uncertain what the marketplace holds for fast-growing salmon. The conflict over genetic engineering has touched a nerve, and members of the International Salmon Growers Association have already decided not to use genetically-modified fish. Regardless, the developers of Aqua Advantage Salmon say they'll press ahead, and plan to file their FDA application later this year. For Living on Earth, I'm Diane Toomey on Prince Edward Island, Canada.

WOMAN: Go PJ, go PPT, go 1-2-3-5-5-7-5-2-4-A...



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