In a letter written to The Columbia Valley Pioneer on April 1st, Richard Hoar claims that genetically modified rainbow trout are being stocked into British Columbia lakes. This is simply not true. Unfortunately, it seems Mr. Hoar has been misinformed about the differences between genetically modified organisms (GMOs) and triploid fish the two are very different. As a representative of the Freshwater Fisheries Society of B.C., I wanted to take this opportunity to clear up some of the confusion around this issue for your readers.
First, triploid fish are not GMOs as is suggested by the letter to the editor. Genetically modified animals are organisms that have had their DNA molecules altered by genetic engineering. On the other hand, triploid fish have the identical genetic composition as their (wild) parents.
Triploidy is a condition that can occur naturally in salmon and trout (albeit at very low rates) that makes the affected animals reproductively sterile.
The B.C. Freshwater Fisheries Society uses a pressure-shocking process at the fertilization stage of egg development in our hatcheries to create entire groups of fish that are virtually 100% triploid. Through this relatively simple pressure-shocking process nothing genetic is introduced, moved or taken away so the fish are not genetically modified in any way.
Additionally, it was mentioned in the letter that triploid trout grow larger and faster. In fact, research in B.C. and elsewhere clearly demonstrates that triploid trout do not grow faster.
However, as they never sexually mature they do tend to live longer and, if they are not caught, a few individuals may reach larger sizes but this is not necessarily a bad thing in a recreational fishery!
Mr. Hoar correctly states that our sterility rates are generally between 98-100% so sometimes a few fish may remain reproductive but these fish are genetically identical to their (wild) parents. To be clear, triploid fish are not genetically modified and are used in the B.C. stocking program simply because they are reproductively sterile.
From a population genetics and fisheries management standpoint, the stocking of sterile fish in some situations allows fisheries managers to either protect wild stocks from genetic interaction with stocked fish or to provide angling opportunities where they otherwise would not exist, or both.
This is a progressive and responsible approach endorsed by both levels of government, as well as most conservation biologists and informed anglers.
President, Freshwater Fisheries Society of B.C.