WILD SALMON THREATENED BY FISH FARM SPECIES
THE NEW YORK TIMES, October 1, 1996.
New research revealed that more than one fourth of salmon spawning in Norwegian rivers and streams are escapees from fish farms. The species from the fish farms are hatched in metal tanks, vaccinated against infections, and raised in sea pens artificially lighted to speed maturation. After five generations, the genes of the farm stock favor fast growth and a high fat content. Lars Petter Hansen, the scientist at the Norwegian Institute for Nature Research who conducted the research, said, "The heavy numbers of escaped farm fish make us believe that the genetic constitution of wild stocks will change so that they will be less adapted to their local habitats." Wild salmon have homing instincts that aid them in finding their native streams after spending a lifetime at sea, whereas farm salmon tend to swim up whichever stream is nearest at spawning time. Wild salmon are genetically different from one river to the next, and the fear of crossbreeding with strays will erase the river-specific characteristics necessary for long-term survival. During a series of storms in 1990, approximately four million fish escaped from fish farms into Norwegian waters, and in 1992 another large breakout occurred during a hurricane. An estimated 200,000 to 650,000 salmon escaped in 1995. In the Saltdals Fjord, near Bodoe, 90 percent of the salmon netted over several weeks last summer were identified as farm fish. In American rivers, wild Atlantic salmon are almost extinct. Research in Canada and the U.S. is preliminary, but the Magaguadavic River in New Brunswick has become a prevalent area for scientific studies on the effects of intermingling of wild and domesticated fish. DNA studies comparing today's wild salmon in the river with specimens preserved from the 1970's show there had been unwelcome cross-breeding. Walter Gibbs, "Fish Farm Escapees Threaten Wild Salmon,"
It should also be noted that the genetic stocks of wild salmon have also been stressed by overfishing the large fish leaving predominantly the genes for smaller slower-growing fish in the natural gene pool. This process is self-defeating.
New Scientist 27 Jan 1996 Can we make Supersalmon Safe?
New Scientist 6 January 1996 Altered Salmon Grow by Leaps and Bounds
This week genetically altered salmon injected with genes for a growth factor which will make tham grow at up to ten times the normal rate will be introduced to a hatchery on Loch Fyne. This is a gene for salmon growth hormone with a trasgenic promoter from the ocean pout. This over-rides the tissue specifity of salmon growth factor and the winter signals to slow growth, but does not effect their eventual size, which is limited by the onset of sexual maturity.
Will these transgenic fish escape and further confound the
natural salmon gene pool?
What are the ethics of such changes, given the known list of escapees above?