June 8, 2010

Genetically-modified rainbow trout much larger than usual are already being produced at a laboratory in Rhode Island, which is expected to lift aquaculture in the US.

Two rainbow trouts of the same age were raised in the same tank. But the larger one has been genetically modified. 

"You can see this enhanced muscling and these are the parent stock. The other fish on the bottom doesn't have the increased muscle mass. So we know this fish has about 20% more muscle mass than the standard fish has," Professor Terry Bradley, research lead at [the Department of fisheries and veterinary science at] the University of Rhode Island, explained.

The process starts in a laboratory. Over the last four years, Dr Bradley has injected 20,000 rainbow trout eggs with a DNA variation which inhibits a protein that restricts muscle growth.

"Each egg and the micro pump is set to deliver five nano-liters of DNA which you cannot see it.  We put dye in it, so all you see is this tiny little dot inside the egg, of green food coloring, and that's the only way you know it has been injected," he said.

The research will continue for a few more years before a larger and more efficiently-growing rainbow trout can move on to the commercial markets.  Bradley says the final goal is to increase the overall efficiency of aquaculture.

USDA says the value of aquaculture production rose to nearly US$1 billion in the US over the past 20 years, mostly due to growing demand for fish in general and harvesting restrictions on wild fish.

Mark Mirando, who is with the Department's National Institute of Food and Agriculture, says the rapid growth of aquaculture is linked to population growth.

"The demand for seafood in the US and worldwide is rapidly increasing but the ability of the oceans to supply that food, even at the current levels, disregarding population increases and increases in demand; the ability of the oceans to supply that is diminishing," Mirando said.