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Hi guys: Just wanted to let you know, in case you haven't already heard, we have some time before our salmon stocks suffer the same fate as those of Scotland and Norway. The BC government has made it clear that they are not about to lift the moratorium on expansion of the industry. The main reason? Escaped salmon. There are too many of them out there and the government seems to realize that there have to be more sound technological advancements that will reduce the numbers of escaped fish before they will lift the moratorium. However, this does not address the problems related to spread of disease and parasites from existing farms.
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just an interesting comment from Jeff, the mackeral guy. I paid for my own research of mackeral on salmon stocks and the foundation food that salmon eat. We all know what mackeral did to salmon. What is really interesting is whether the mackeral carried any diseases and / lice / worms in their digestive tracts etc. My estimate based upon catches by sporties, and the occasional DFO research surveys was about 15 to 17 million mackeral in our pacific coast waters. To date we the sporties, and the commercials and DFO scientists have not detected any unusual cross over diseases or worms, or lice or liver flukes whatever from the huge hordes of millions of mackeral. So can someone please show me the science behind the Atlantic salmon disease problem. I know the mackeral is a different species but diseases worms, lice, flukes, whirling disease what ever can mutate given the right combination of conditions. Maybe we should ask Suzuki foundation and DFO, UBC oceanographic studies to make this disease thing a priority. Because the mackeral will be returning along with all sorts of fishes that are not resident to our waters. Whirling disease is the problem which really concerns me in the immediate future. regards from a non scientist.
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Jeff: Many of the diseases carried by Atlantic salmon are easily passed on to Pacific salmon and trout because they are of the same family "Salmonidae". Typically, they are all afflicted by diseases such as furunculosis, viral hemopoeatic septicemia (VHS), bacterial kidney disease (BKD) and infectious salmon anaemia (ISA). These are all diseases common to fish farming and to fish that spend part of their life in fresh water. The diseases are prevalent in the marine and/or freshwater environment. However, they usually don't become a problem unless the fish are stressed, such as they would be in a crowded pen. (Think of people and the flu. The flu is much more common anywhere people congregate. If you live in country, your chances of coming in contact with infected individuals is smaller.) Once the disease takes hold in a fish farm, the number of bacteria/viruses increase exponentially and they spread. Furunculosis, for example, has been detected in high concentrations up to 25 miles from infected fish farms. Migrating fish passing through the area can simply pick up the disease by contact (i.e. water passing over the gills). Infection is instantaneous. Whether the fish shows signs of the disease will depend on a number of factors (i.e . stress from high water temperatures or streeful migration, etc...). A fish can be infected in the marine environment and will not show signs of the disease until they enter fresh water (a physiological response to stress). Also, sea lice, which attach to salmon and steelhead are known disease vectors. They are host specific and do not affect other species like mackeral. Once infected, salmon and trout can pass these diseases on to their progeny through the eggs and sperm. This makes the diseases more troubling because fry can be infected as soon as they hatch from viral organisms attached to the out layer of the egg case. In the case of furunculosis, mortalities in fry from infected adults can be as high as 90%. This is true even if the adults showed no external sign of the disease before spawning. It seems obvious to me that mutation of disease organisms and their likelihood of transferrance would be greater between fishes of the same family than between fishes of different families (completely different physiologial and biological characterstics). There are some excellent web sites on this stuff. The National Oceanic and Atmospheric Agency (NOAA)has been doing lots of work on this. Hope this helps. A biologist
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