Research fuels worry about genetically altered fish and the environment
By Sandi Doughton
The Seattle Times
13th June 2004
In a head-to-head battle for food, normal coho salmon lose out to their genetically engineered cousins, says a new study that adds to the controversy over what critics call "frankenfish."
Not only did the aggressive, gene-modified salmon gobble up most of the feed when raised in tanks with ordinary salmon, but they also gobbled up their weaker competitors - including their own type, British Columbia scientists reported in the June 7 online edition of the Proceedings of the National Academy of Sciences.
The results were often dramatic population crashes, with only one or two of the genetically modified fish surviving in tanks that originally held 50 animals, said lead author Robert Devlin of Fisheries and Oceans Canada.
"When food supplies are low, transgenic (genetically modified) fish have a very significant effect on the population," he said, adding the caveat that laboratory experiments may not predict what would happen if bioengineered salmon escaped into the environment.
But that's a question that needs to be answered soon.
Massachusetts-based Aqua Bounty Farms has asked the U.S. Food and Drug Administration for approval to market what could be the first transgenic food fish: Atlantic salmon that grow twice as fast as normal fish. Aqua Bounty hopes to raise its transgenic salmon in coastal net pens in the United States and market the eggs around the world, said Joseph McGonigle, vice president for external affairs. "We are constantly hearing from companies that are interested in it," he said.
Faster growing salmon would cut costs dramatically for fish farmers and lead to lower prices in the supermarket, McGonigle said.
Consumer groups, commercial fishermen and some scientists say studies such as Devlin's show the potential ecological consequences of unleashing man-made breeds of fish.
"We should not be taking a risk like this at a time when native salmon stocks are already in trouble," said Doug Gurian-Sherman, senior scientist at the Center for Food Safety, a consumer group based in Washington, D.C.
A 2002 National Academy of Sciences report expressed moderate concern that genetically engineered fish might pose risks to consumers if, for example, a person who was allergic to scallops ate fish with a scallop gene spliced into its DNA. But experts agreed that the biggest danger is that some of the gene-modified fish would inevitably escape into the environment.
Hundreds of thousands of Atlantic salmon have escaped into Northwest waters from salmon farms over the past several years when floating pens were ripped apart by storms or marauding sea lions.
The worst-case scenario involving transgenic fish is the "Trojan gene" hypothesis proposed by Purdue University geneticist William Muir: Genetically engineered salmon out compete normal fish for food and mates, leading to less-hardy hybrids and the eventual extinction of the entire wild population.
McGonigle says the net pens would hold only sterile females, eliminating the possibility that escapees could breed in the wild. Several other studies, including some in Devlin's lab, have shown that the genetically engineered fish aren't likely to survive well outside of captivity because they're more susceptible to disease and oblivious to predators.
"We realize we have no chance of getting approval unless we can clearly demonstrate these fish are completely sterile, and they represent no genetic threat and no behavioural threat, in terms of competition for resources," he said.
Washington's Fish and Wildlife Commission banned genetically engineered fish from marine net pens, but the state has no rules that bar them from land-based tanks or fresh water, said John Kerwin, who manages the state's hatchery program. Oregon has similar restrictions, while California bans the creatures entirely - including the fluorescent Glo Fish, a genetically engineered aquarium fish that went on sale last year.
Devlin's research for the Canadian government is attempting to unravel the possible effects of genetically engineered food fish before they're approved.
"We're just starting to gather the kinds of laboratory information which we hope will provide us with understanding about these animals," he said.
He works with coho salmon that overproduce growth hormone as a result of genetic tinkering. Aqua Bounty's Atlantic salmon were engineered in a similar way, using genes from chinook salmon and a species called ocean pout.
In both cases, the genetically engineered fish grow much faster than ordinary fish but don't get much bigger at maturity.
At 1 year of age, Devlin's gene-engineered fish are 10 times the size of ordinary coho.
For the study reported June 7, Devlin and his colleagues manipulated the amount of food available to the fish. When food was abundant, normal and genetically modified fish coexisted well. It was only when food was scarce that competition turned deadly for the normal fish.
While populations made up only of normal fish were able to ride out food shortages, mixed populations invariably crashed.
But the experiments also revealed another wrinkle: Populations made up have only genetically engineered fish also crashed when food supplies were low.
Does that mean transgenic fish might pose little risk if they escaped into the environment because they would die out when food supplies drop?
It's possible, Devlin said.
"If you had a small population, where the fish couldn't migrate out of the area, transgenic fish might eat themselves out of house and home and there would be no risks," he said.
But on the other hand, if numbers boomed when food was plentiful, the bioengineered fish could devastate normal fish in the cutthroat competition that would ensue.
McGonigle says he hopes to have an FDA ruling within the next two years, but the target date has been pushed back repeatedly.
Because of regulations to protect businesses, the agency's evaluation process is largely secret, leading critics to call for a new system that is open and gives more authority to environmental and wildlife agencies.
"FDA has absolutely no experience with these kinds of issues," said Gurian-Sherman, the Center for Food Safety scientist. "And we know nothing about what they're doing."