A study from the University of Gothenburg, in Sweden, cautioned that by giving some fish genes from other organisms – so-called transgenes – researchers have succeeded in producing species that are able grow considerably more quickly than non-GM fish and are more resistant to diseases. However, the robust nature of transgenic species means they can have a higher tolerance to toxins.
Fredrik Sundstrom, of the Department of Zoology, said the ability of transgenic fish to be more resistant to environmental toxins could entail the greater accumulation of toxins that “ultimately end up in consumers”. He added that there were “misgivings that the higher level of growth hormone in the fish can affect people”.
The report, commissioned by the European Union, acknowledged that GM breeding had the potential to revolutionise commercial fish farming – delivering higher production and better yields. It would also ease of pressure on over-exploited fish stocks and could result in a lowering of raw material prices for fish processors.
However, potential hazards to humans and the risks posed by the fish studied in the research escaping from farms into the wild means GM species should be “treated with great care” and reared in closed systems on land until further notice, said Sundstrom.
Threat to natural breeds
As well as examining implications to human health, the report also looked at any ecological threat posed by transgenic salmon and rainbow trout to the natural environment if they escaped from enclosed commercial breeding farms. Researchers found that GM fish “have a considerably greater effect on the natural environment than hatchery-reared non-transgenic species when they escape”. This is most likely due to their ability to cope better with food shortages and changes in water temperatures, noted the report.
“It is probably due to the fact that genetically modified fish have a greater ability to compete and are better at converting food,” Sundstrom added.
But the study said it was unable to predict if the escaped GM fish would outperform natural species over time if they became established in natural stocks.
Sundstrom concluded that broad international consent was needed before commercial farming was given the green light and that a precautionary approach should be applie.