It is a discussion forum where members can freely express their views and contribute to the discussion how they wish (within forum guidelines). People contribute in their own way - that should be the “intent”, in my opinion. I find it disheartening to see what should be a meaningful and interesting discussion sink into a dirty pit of condescending remarks, personal attacks and labelling. In my opinion, it takes two to tango and bad behaviour is not limited to just one group or the other. Secondly, silence shouldn’t get interpreted as not having an opinion, not interested or not knowledgeable enough. Sometimes it is lack of interest in maintaining a lengthy discussion when it seems like others are not really listening or the discussion turns into mud-slinging. I especially lose interest when conspiracy theories are repeatedly brought up. These discussions also have to be balanced with work and family life. Lately, I have been so busy at work. Hiding data and taking kick-backs take up a lot of time (sarcasm of course) Lastly, I can learn valuable insight from others also on here, but like Ukee, I realize that there is a wealth of published, scientific data on the subject. Twenty years of work experience as well as knowledge gained from folks that work in fish health has taught me what is good information to take in, what is not and when to refer to the experts that truly know their stuff.
No ISA in BC CFIA
- Thread starter Birdsnest
- Start date
It is a discussion forum where members can freely express their views and contribute to the discussion how they wish (within forum guidelines). People contribute in their own way - that should be the “intent”, in my opinion. I find it disheartening to see what should be a meaningful and interesting discussion sink into a dirty pit of condescending remarks, personal attacks and labelling. In my opinion, it takes two to tango and bad behaviour is not limited to just one group or the other. Secondly, silence shouldn’t get interpreted as not having an opinion, not interested or not knowledgeable enough. Sometimes it is lack of interest in maintaining a lengthy discussion when it seems like others are not really listening or the discussion turns into mud-slinging. I especially lose interest when conspiracy theories are repeatedly brought up. These discussions also have to be balanced with work and family life. Lately, I have been so busy at work. Hiding data and taking kick-backs take up a lot of time (sarcasm of course) Lastly, I can learn valuable insight from others also on here, but like Ukee, I realize that there is a wealth of published, scientific data on the subject. Twenty years of work experience as well as knowledge gained from folks that work in fish health has taught me what is good information to take in, what is not and when to refer to the experts that truly know their stuff.
The target number of samples for IHNv was not reached because due to commercial fishery closures in 2013. Collecting samples for analysis like this is not easy and as straightforward as it may look on the surface. There are always logistical issues to overcome. Anyone can collect fish samples, but to collect good, reliable fish samples is not easy. It’s not as if the CFIA has their own boats and crew out there with nets collecting fish for samples. That’s why they partner with so many groups in order to get as many samples as possible from a variety species and locations. Samples need to have an established chain-of-custody because it can put the results in doubt if you don’t know how they have been handled from the time to capture to the time of analysis. The crappy thing is that a bad sample might not show it’s ugly head until after it’s been prepared. This means that it might not be a good idea to just go soliciting random individuals to just bring in samples.
Secondly, there is no scientific study that I know of goes off without a hitch (especially with fisheries). Researchers are human, fish don’t always do what we think they will do and researchers don’t control fishery openings. It’s not that they are incompetent or secretly hiding something. One the labs used in the study was from the Pacific Biological Station. Those folks know what they are doing. It is not uncommon to have things not going according to plan (i.e. not able to reach some target amounts). It doesn’t necessarily mean that the study is garbage, but things that don’t go according to plan should be brought up in the report and you will find out that it is. However, if you still believe that it puts the whole testing regime under suspicion that is your opinion and you are entitled to that, but it's not mine. If you want to get mad take it out on the Lions right now as they losing.
Alaska is less concerned about the BC fish. One cannot say Alaskans are unconcerned about this virus or potential wild fish/farmed fish pathogen interactions as they ban finfish farming entirely in Alaska. Washington is less concerned as we tend not to site net pens in terminal fisheries (and we don't have near as many as BC). I think the areas of prime concern are where net pens are placed in terminal fisheries or near significant concentrations of out migrating smolts. BC is a place where there is extensive siting of fin fish in terminal fisheries and near shore smolt migration.
Birdsnest
Well-Known Member
Show me an alaskan salmon ranching operation that doesn't have net pens holding fish during wild outmigrations right/RIGHT at the river mouths of wild run salmon species that are capable of carrying isa or any other viruses for that matter.
This link has another good photo as an example: http://www.certifiedorganic.bc.ca/rcbtoa/services/NAsept-oct-pgs14-15c.pdf
This link has another good photo as an example: http://www.certifiedorganic.bc.ca/rcbtoa/services/NAsept-oct-pgs14-15c.pdf
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Apples and oranges BN - when comparing the open net-pen industry in BC that grows Atlantic salmon until harvest (some 18th months, across the smolt outmigration - right?) and the net-pens in front of the hatcheries in AK that stock natal Pacific salmon for a few weeks - for 2 reasons:
1/ Length of time in net-pens, particularly when trying to mitigate risk to outmigrating juvenile salmon in areas with high densities of such smolts (e.g. Discovery Islands and the Broughtons), and
2/ The fact that the local hatcheries use local brood stock (presumably as susceptible, adapted and/or 'diseased" to local diseases as their cousins from the same watershed going by) - and only present there for a few weeks.
Risk assessment and management is a combination of likelihood and consequence. The more smolts going by - the higher the likelihood of interactions. The more poorly-placed any particular site is - the higher the consequence. If you are comparing risks - you need to compare likelihood times consequence.
Oh ya - who/what is APHIS?
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Agree with what you say Sushwap - however - did you look at the disease zones? Do you know about salmon CUs and the Wild Salmon Policy? Did you see that they use the Kitimaat hatchery as their sentinel hatchery for all of the North Coast - and Prince George on the Fraser drainage is also thrown in?
Birdsnest
Well-Known Member
3 weeks eh. lol Are you sure about that? What would be the point of holding them for 3 weeks agent? I am certain that holding/feeding time may vary from species to species but 3 weeks would be pointless. Take another try at that number and TRY to be honest. I actually cant find that information but from my knowledge a three week holding time would accomplish nothing in terms of survival and returns. Im getting Three month from this, but your not going to like it: http://www.certifiedorganic.bc.ca/rc...-pgs14-15c.pdf
APHIS:http://www.aphis.usda.gov/wps/portal/banner/aboutaphis
APHIS:http://www.aphis.usda.gov/wps/portal/banner/aboutaphis
Birdsnest
Well-Known Member
The majority of out migrations for most species in alaska would be during the times that those ranched fish are held, even the outmigrations a year later are going to meet fish in pens in high densities in alaska. Coho would be a good example of this. Your comment is based on european viruses which are proven to not exist with the exception of PVR which is shown to have been here since 1977 and found in alaska and washington. Still tho alaska salmon ranchers seem to have no problem having their smolts right in front of river mouths during wild outmigrations. You cant see an issue with that?
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OldBlackDog
Well-Known Member
So, try this.
Check out how many wild caught fish of all species are tested in Canada.
Last time i checked it was next to none.
So of all the wild fish sold none are tested for diseases, toxins etc.
We know for a fact that seals that have been tested are so toxic that they must be disposed as toxic soil is.
Seals eat fish. Something is missing here.
Check out how many wild caught fish of all species are tested in Canada.
Last time i checked it was next to none.
So of all the wild fish sold none are tested for diseases, toxins etc.
We know for a fact that seals that have been tested are so toxic that they must be disposed as toxic soil is.
Seals eat fish. Something is missing here.
I am familiar with Fraser Sockeye CUs not so much with the others and the WSP is a never ending saga. Not sure what these have to do with the study; however, the study does go into the reason for using sentinel hatcheries. As for Prince George location I noticed it on the map....It appears to be Naver Creek and it could be adult broodstock collection site according to the map, possibly for Chinook. It is possible that one of these sentinel hatcheries has taken broodstock from that location - I don't know. Naver Creek is a monitoring site for Chinook.
This is all very interesting and the issue of ISA and ISAv prevalence in BC fish, wild and farmed, has been discussed ad nauseam, on this and other sportsfishing sites; mostly by anonymous posters (yeah, that’s you aa, lol!). But it seems we do have a very qualified scientist, Seadna, who is willing to discuss and share with us his thoughts on these issues. I thank him for that and am looking forward to his comments when he has read this report.
Are you sure about your reply? Are you getting as old as me as to need glasses now, BN? I said a FEW weeks!
AGAIN, BN - you are obviously NOT reading what I post:
Time to get glasses! LOL
They use sentinel hatcheries because it is convenient, and the broodstock was going to be killed anyways - that's why. Makes sense to build on what you already have. Then they tried to move boundaries around to try to justify using a particular DFO-funded hatchery to cover-off retwerked disease zones. Those disease zones should be watershed-based - and they clearly are not, as can be referenced by the maps in the Appendices. It they wanted to test a certain percentage of the population - you would want to know what the escapements were by watershed - which they have not done.
I would assume that the kitimat river can be stated as being tested - since they use the Kitimat hatchery - as previously discussed. If the average annual escapement to that river is 82CO, 800CM, 80CH, and 10,000PK - to use arbitrary but realistic numbers - then if they want to test enough fish to have a statistically valid test result (1% apparent prevalence, 85% test sensitivity, 100% test specificity, 95% confidence in detecting disease if present) - as stated - then they would stratify their sampling to cover that off for that watershed escapement numbers.
However, they state that The target number of samples per Area remained 175 juveniles and 175 adults. Then they draw arbitrary boundaries on "that area" that have demonstrate no understanding of watershed boundaries and the target number of samples per Area does not look at escapement numbers by species.
Stocks from Hartley Bay North to the Alaskan border likely would not ever come close to the North end of Douglas and be used as broodstock, although I have heard rumours of Fraser stocks poking their heads into Kemano due to the fact that some of the water of the Fraser drainage empties out through that diversion.
Wild Salmon Policy: http://www.pac.dfo-mpo.gc.ca/fm-gp/species-especes/salmon-saumon/wsp-pss/docs/wsp-pss-eng.pdf
Conservation Units for Pacific Salmon under the Wild Salmon Policy: http://www.dfo-mpo.gc.ca/CSAS/Csas/DocREC/2007/RES2007_070_e.pdf
Check out the CU maps on this one: http://www.pac.dfo-mpo.gc.ca/fm-gp/...mon/wsp-pss/docs/strats/strat1/CUsummlist.pdf
If we are discussing epidemiology and risk of disease transfer (in FW, using hatcheries as sentinel locations) - why wouldn't watershed CUs be the more appropriate structure to use to stratify your sampling effort and to generate estimates of sampling effort - rather than stretching the aerial boundaries of an arbitrary mapping exercise that tries to incorporate hatchery locations to randomly cover off large areas? PG is on the Fraser drainage and not connected to Prince Rupert except by road. Didn't know fish could drive vehicles. Seriously...
I would assume that the kitimat river can be stated as being tested - since they use the Kitimat hatchery - as previously discussed. If the average annual escapement to that river is 82CO, 800CM, 80CH, and 10,000PK - to use arbitrary but realistic numbers - then if they want to test enough fish to have a statistically valid test result (1% apparent prevalence, 85% test sensitivity, 100% test specificity, 95% confidence in detecting disease if present) - as stated - then they would stratify their sampling to cover that off for that watershed escapement numbers.
However, they state that The target number of samples per Area remained 175 juveniles and 175 adults. Then they draw arbitrary boundaries on "that area" that have demonstrate no understanding of watershed boundaries and the target number of samples per Area does not look at escapement numbers by species.
Stocks from Hartley Bay North to the Alaskan border likely would not ever come close to the North end of Douglas and be used as broodstock, although I have heard rumours of Fraser stocks poking their heads into Kemano due to the fact that some of the water of the Fraser drainage empties out through that diversion.
Wild Salmon Policy: http://www.pac.dfo-mpo.gc.ca/fm-gp/species-especes/salmon-saumon/wsp-pss/docs/wsp-pss-eng.pdf
Conservation Units for Pacific Salmon under the Wild Salmon Policy: http://www.dfo-mpo.gc.ca/CSAS/Csas/DocREC/2007/RES2007_070_e.pdf
Check out the CU maps on this one: http://www.pac.dfo-mpo.gc.ca/fm-gp/...mon/wsp-pss/docs/strats/strat1/CUsummlist.pdf
If we are discussing epidemiology and risk of disease transfer (in FW, using hatcheries as sentinel locations) - why wouldn't watershed CUs be the more appropriate structure to use to stratify your sampling effort and to generate estimates of sampling effort - rather than stretching the aerial boundaries of an arbitrary mapping exercise that tries to incorporate hatchery locations to randomly cover off large areas? PG is on the Fraser drainage and not connected to Prince Rupert except by road. Didn't know fish could drive vehicles. Seriously...
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Birdsnest
Well-Known Member
A few weeks is NOT 3 months.
Sorry agent if I have reduced you to responding with "your not reading my posts". If your primary response to the information I post is "your not reading my post" then I cant help you. Its clear how you look at the issue:
I agree there are differences between salmon ranching and salmon farming but based on all the doomsday scenarios you have presented about salmon culture in salmon farming how can you deny that the same level of risks exists in salmon ranching as shown in this photo and discussed in my previous posts?
Again Questions:
Why is this testing on the east coast so cut and dry where here in BC it so "complicated"?
What makes the 2 locations so different in terms of this testing?
They cant scientist seem to find it in washington or alaska?
Will you acknowledge the statements about the risks of ISA from Alaska, Washington, And Oregon.
Important considerations regarding the B.C. ISAv:
- Research on ISAv indicates that risk to Alaska’s salmon stocks is low. Pacific salmon are relatively resistant to infection and disease from ISAv, which is a viral disease of Atlantic salmon. The susceptibility of sockeye salmon to ISAv has not been experimentally tested. Other Pacific salmon including Chinook, coho, and chum salmon as well as steelhead trout do not develop disease when injected with the Norwegian strain of ISAv, but may become infected and carry the virus for varying periods of time. However, injection is an unnatural route of infection that would not occur in nature.
- Other strains of ISAv in North America are not pathogenic in Atlantic salmon. However, these viruses can mutate into more virulent strains, therefore we have cause for some concern.
- Atlantic herring reportedly carry the virus, but do not become diseased. This forage species could act as a reservoir and source of the virus.
- Although live Atlantic salmon are prohibited from importation into Alaska, there is some straying of escapees from B.C. farms, which could provide an avenue for the virus to enter Alaska waters. However, ISAv testing by PCR of Atlantic salmon (4,726 tests) from B.C. farms by the Canadian government over the last 8 years, including the past three months, has been negative for the virus. Therefore, the risk of virus transmission from such escapees is very low.
- ISAv does not transmit to humans and is not a human health or food safety issue.
http://www.dfw.state.or.us/resources...Fact_Sheet.pdf
http://www.aphis.usda.gov/publicatio...pacific_nw.pdf
My point isnt so much that salmon ranching is bad but that that salmon ranching has been going on for a long time as described and there has been no "event" in terms of a disease outbreak causing widespread devastation of salmon stocks there, all the while having scenarios very similar to salmon farming in bc.
I fixed this for you so now can you tolerate to respond? Geesh.
One other thing, Farming atlantic salmon does not damage wild salmon genetics as salmon ranching does. You can state that its great to use natural brood stock but most here know it not without its issues.
Im posting allot of items twice now in hopes that you don't see past it.
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Not sure if I have enough time right now to fully cover all of your points - but shooting from the hip:
Risk is an assessment of likelihood TIMES consequence. BOTH are elevated wrt large numbers of juvenile salmon going past open net-pen sites. The longer that net-pen is in operation - the more multi-year stocks it contains - and the more ill-placed it is wrt location and interactions - the more risk it incurs.
So - NO - they aren't the same for the reasons discussed above - apples and oranges. I would post more on this when I have more time.
2 - Agree the problem.
3 - herring risk - agree. My "doomsday" scenario.
4 - in the middle of this discussion right here and now on this thread.
5 - red herring. Population-level impacts the problem.
Oh ya - the APHIS website...Were you posting this for a reason?
AGAIN - reference back to the discussion on risk assessment and management. I think we are all trying to dealing with those risks, so-called "antis" AND so-called "pros" sides.
Risk is an assessment of likelihood TIMES consequence. BOTH are elevated wrt large numbers of juvenile salmon going past open net-pen sites. The longer that net-pen is in operation - the more multi-year stocks it contains - and the more ill-placed it is wrt location and interactions - the more risk it incurs.
So - NO - they aren't the same for the reasons discussed above - apples and oranges. I would post more on this when I have more time.
It is "complicated' wrt cell culture for both coasts, but ISA in endemic on the East Coast - we are not sure yet about this coast, and you referenced below in your post on non-pathogenic ISA. Viruses mutate. End and beginning of story.
1 - agree low - low is not zero. Never will be zero using open net-cage verses closed containment methods. If we had scientifically defensible siting criteria, and adequate and publicly-accessible surveillance - we could live with this.
2 - Agree the problem.
3 - herring risk - agree. My "doomsday" scenario.
4 - in the middle of this discussion right here and now on this thread.
5 - red herring. Population-level impacts the problem.
See discussion on risk.
On genetic effects - Agree ONLY on Pacific drainages wrt Atlantic escapees. NOT Atlantic watersheds. Escapees also have non-genetic risks. Agree on strengths/weaknesses of hatcheries. Long discussion on that - that I (and Dave and Shuswap) posted on - at: http://www.sportfishingbc.com/forum...on-can-adapt-to-warmer-environment-study-says
Oh ya - the APHIS website...Were you posting this for a reason?
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Traxler et al. (1997) p.36: All sockeye salmon populations along the Pacific coast of North America examined to date are infected with IHN http://www.int-res.com/articles/dao/28/d028p031.pdf - yet CFIA tested 1272 samples for IHN and got ZERO positives? And I am the one who is mistaken in my "suspicion" that something is amiss - and who is "entrenched" in my "belief" w/o examining the science - simply because I question the results - and subsequently have been shoved in a particular category of antis verses pros? Wanna rephrase, Ukee?
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I've obtained and read through the report. I've submitted a few questions to those who supplied the report asking for some details about the methodology. In particular, I want to understand how they handle the samples prior to the culture based tests and I want to understand what they use for positive controls to assure that the testing methods they are using will detect virus if it is present. My concern remains that the testing methods appear to require a positive culture based result and I'm worried that this may result in a high false negative rate. If that's controlled for in an appropriate way AND the actual false negative rate is similar to or less than that assumed in their sample size calculations, the rest of their plans seems fairly reasonable to me.
However, I note that they could go a LONG way to improving the perception of openness and integrity in their process with the following steps:
1) Just post the full reports online instead of making one go through a gate keeper to get them.
2) Post the full protocols online
3) Post summary data online - in particular what percentage of the samples were positive by PCR and negative by culture? I'd really like to know the answer to that one. If there was no detection by PCR, then my concerns about false negatives in the culture based confirmatory tests would be moot. If a significant percentage were positive by PCR but not confirmed by culture, I'd want to be convinced that the PCR detections were false positives - this could be done by sequencing the PCR products and showing that the sequences are not the targeted viruses.
I also think that the integrity of the process would be less open to question if the reporting of confirmed cases was in real time (as opposed to delayed) and if more detail were provided (actual location as opposed to a general area). Also, the government scientist should not feel like they are muzzled and should be able to speak freely about the process and data. I must admit that the level of suspicion of these reports would be MUCH lower, if the entire system was more open.
However, I note that they could go a LONG way to improving the perception of openness and integrity in their process with the following steps:
1) Just post the full reports online instead of making one go through a gate keeper to get them.
2) Post the full protocols online
3) Post summary data online - in particular what percentage of the samples were positive by PCR and negative by culture? I'd really like to know the answer to that one. If there was no detection by PCR, then my concerns about false negatives in the culture based confirmatory tests would be moot. If a significant percentage were positive by PCR but not confirmed by culture, I'd want to be convinced that the PCR detections were false positives - this could be done by sequencing the PCR products and showing that the sequences are not the targeted viruses.
I also think that the integrity of the process would be less open to question if the reporting of confirmed cases was in real time (as opposed to delayed) and if more detail were provided (actual location as opposed to a general area). Also, the government scientist should not feel like they are muzzled and should be able to speak freely about the process and data. I must admit that the level of suspicion of these reports would be MUCH lower, if the entire system was more open.
Charlie
Well-Known Member
Sedna,
Tread cautiously and don’t fall into the word game DFO plays concerning their use of the term “infectious salmon anaemia (ISA)" in that news article.
http://news.gc.ca/web/article-en.do?nid=902639
DFO knows full well they are NOT stating ISAv isn't in BC and they are only referring to "infectious salmon anaemia (ISA)" the disease. Whenever they use that term they are only speaking of the “disease” AND, to date that is true - the ISA “disease” has never been proven to exist anywhere in BC, along with Alaska, Washington, Oregon, Idaho, or California.
Now, getting DFO to talk about all of their "positive" RT-PCT testing - GOOD LUCK! You will get a LOT from DFO about "false positives," "could not duplicate," "poor samples," and "lack of chain of custody." One thing I am sure of is ISAv (virus not disease) surely is here and has been found by DFO through their RT-PCT testing. DFO themselves have repeatedly shown their "positive" ISAv test results and since no proven ISA disease has ever been proven - YET. DFO keeps ignoring those and writing them off as “false positives.” If one doesn't believe this, just contact DFO’s own Dr. Kristy Miller ask. She actually did report her "positive" ISAv test results to - none other than CFIA. And, that is in the Cohen Commission records. What ever happened there?
Now with that… people seem to keep forgetting ISAv Genotype HPR0 and HPR00 - CANNOT BE CULTURED! You can give DFO all the "positive" RT-PCT tests you want and DFO will NEVER admit to ISAv in BC. UNTIL, there UNTIL the Genotype HPR0 and/or HPR00 mutates (which it will), or there is confirmed ISA "disease" outbreak (which there will be) in BC. IF they do, Canada will lose some very valuable trading partners and both CFIA and DFO have already been told that!
FYI... those “positive” RT-PCT tests DFO received showing the ISAv (virus) found in BC are of the Norway Genotype. Another FYI The east coast ISA “disease” also originated from the Norway Genotype and was/is only “cultured” and confirmed AFTER the fish come down with the ISA “disease.” That is very much why ISAv has been confirmed on the east coast and not here on the west coast. It will only been confirmed here after it mutates, kills our salmon, and can be cultured.
Tread cautiously and don’t fall into the word game DFO plays concerning their use of the term “infectious salmon anaemia (ISA)" in that news article.
http://news.gc.ca/web/article-en.do?nid=902639
DFO knows full well they are NOT stating ISAv isn't in BC and they are only referring to "infectious salmon anaemia (ISA)" the disease. Whenever they use that term they are only speaking of the “disease” AND, to date that is true - the ISA “disease” has never been proven to exist anywhere in BC, along with Alaska, Washington, Oregon, Idaho, or California.
Now, getting DFO to talk about all of their "positive" RT-PCT testing - GOOD LUCK! You will get a LOT from DFO about "false positives," "could not duplicate," "poor samples," and "lack of chain of custody." One thing I am sure of is ISAv (virus not disease) surely is here and has been found by DFO through their RT-PCT testing. DFO themselves have repeatedly shown their "positive" ISAv test results and since no proven ISA disease has ever been proven - YET. DFO keeps ignoring those and writing them off as “false positives.” If one doesn't believe this, just contact DFO’s own Dr. Kristy Miller ask. She actually did report her "positive" ISAv test results to - none other than CFIA. And, that is in the Cohen Commission records. What ever happened there?
Now with that… people seem to keep forgetting ISAv Genotype HPR0 and HPR00 - CANNOT BE CULTURED! You can give DFO all the "positive" RT-PCT tests you want and DFO will NEVER admit to ISAv in BC. UNTIL, there UNTIL the Genotype HPR0 and/or HPR00 mutates (which it will), or there is confirmed ISA "disease" outbreak (which there will be) in BC. IF they do, Canada will lose some very valuable trading partners and both CFIA and DFO have already been told that!
FYI... those “positive” RT-PCT tests DFO received showing the ISAv (virus) found in BC are of the Norway Genotype. Another FYI The east coast ISA “disease” also originated from the Norway Genotype and was/is only “cultured” and confirmed AFTER the fish come down with the ISA “disease.” That is very much why ISAv has been confirmed on the east coast and not here on the west coast. It will only been confirmed here after it mutates, kills our salmon, and can be cultured.
“The non-cultivable, non-pathogenic viruses detectable only by RT-PCR have the full-length HE protein (designated HPR0 or HPR00 for Genotype I found in Europe or North America, respectively). Because there is presently no universally accepted nomenclature system for designation of genetic relatedness between ISAV isolates, further investigations of different ISAV isolates from different geographical areas are necessary to facilitate comparison of ISAV isolates.”
http://www.virologyj.com/content/6/1/88
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Birdsnest
Well-Known Member
Surely, I mean absolutely, it would appear on an Atlantic salmon farm long before the above dooms day prediction. Even if it was here
https://www.sfu.ca/cstudies/science/resources/1321897737.pdf
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Charlie
Well-Known Member
The part that you are missing, it is already here - just ask Dr. Kristy Miller. Referring to your reference - all is how one "closely" reads and understands that study. I will quote your own reference with my personal comments observations in [ ]:
“Infectious salmon anaemia (ISA) [the disease] is a major disease of Atlantic salmon, Salmo salar, caused by an orthomyxovirus (ISAV) [the virus].”
“No signs typical of ISA [the disease] and no ISAV [the virus]-related mortality occurred among any of the groups of Oncorhynchus spp. in either experiment, although ISAV [the virus] was reisolated from some fish sampled at intervals postchallenge. The results indicate that while Oncorhynchus spp. are quite resistant to ISAV [virus] relative to Atlantic salmon, the potential for ISAV [the virus] to adapt to Oncorhynchus spp. should not be ignored. [pretty clear – should not be ignored]”
“Clinical outbreaks of ISA [the disease] occur in seawater adapted Atlantic salmon reared in marine net pens [there has never been a “clinical outbreak found in the wild – THEY JUST individually - DIE]. However, ISAV [the virus] has also been identified in wild Atlantic salmon (Nylund, Kevenseth & Krossøy 1995a), sea trout, Salmo trutta L., (Raynard, Murray & Gregory 2001a) and Atlantic herring, Clupea harengus harengus L. (A. Nylund, personal communication) although no clinical signs of the disease were present [again, THEY JUST individually - DIE]. Sea trout (Nylund, Alexandersen, Løvik & Jakobsen 1994; Nylund, Alexandersen, Rolland & Jakobsen 1995b; Nylund & Jakobsen 1995; Rolland & Nylund 1998), brown trout, Salmo trutta L. (Snow, Raynard & Bruno 2001), Arctic char, Salvelinus alpinus (L.) (Snow et al. 2001), and rainbow trout (Nylund, Kvenseth, Krossøy & Hodneland 1997; Snow et al. 2001) represent possible natural reservoirs of ISAV [the virus] because the virus is able to propagate in these species without producing clinical disease, while saithe, Pollachius virens (L.), a species commonly associated with marine net pens, was shown not to be a likely reservoir (Snow, Raynard, Bruno, van Nieuwstadt, Olesen, Lovold & Wallace 2002). Recently, Kibenge et al. (2001a) reported isolation of ISAV [the virus] from farmed coho salmon, Oncorhynchus kisutch (Walbaum), in Chile. However, these clinically diseased fish exhibited markedly different pathology from typical ISA [the disease] and although the disease has been associated with an orthomyxovirus, it is reported that the disease in Chilean coho is of multifactorial [involving or dependent on a number of factors or causes. The end result is they don’t show all/or any of the clinical signs of ISA disease but they still - DIE] origin (Smith, Larenas, Contreras, Cassigoli, Venegas, Rojas, Guajardo, Troncoso & Macias 2002).”
“Here, we used a relatively severe challenge dose of ISAV delivered by intraperitoneal injection to show that Pacific salmon were considerably more resistant to ISAV compared with their Atlantic counterparts.
Although our findings suggest Pacific salmon are quite resistant to the strains we used, ISA has been reported to occur in farmed coho salmon in Chile (Kibenge et al. 2001a). However, Smith et al. (2002) have suggested that the disease associated with the orthomyxovirus recovered from Chilean coho salmon may be of multifactorial origin.”
“However, salmonids such as rainbow trout, brown trout and sea trout have been reported to be carriers of ISAV [virus], and the reisolation of ISAV [virus] from the Pacific salmon species used in these trials indicates that it would be unwise [emphasis – UNWISE] to overlook the possibility of ISAV [virus] replicating in, or establishing a carrier status among these species should they be exposed to the virus. Furthermore, the haemagglutinin gene of ISAV [virus] shows substantial diversity among isolates that may be associated with antigenic variation [see below] or recombination (Devold et al. 2001; Kibenge et al. 2001b; Cunningham, Gregory, Black, Simpson & Raynard 2002) and such variation may result in evolution of strains with differences in host range, virulence or immune response to vaccines [to ISA disease].”
Antigenic variation:
“Influenza viruses are constantly changing. They can change in two different ways.
One way they change is called “antigenic drift.” These are small changes in the genes of influenza viruses that happen continually over time as the virus replicates. These small genetic changes usually produce viruses that are pretty closely related to one another, which can be illustrated by their location close together on a phylogenetic tree. Viruses that are closely related to each other usually share the same antigenic properties and an immune system exposed to an similar virus will usually recognize it and respond. (This is sometimes called cross-protection.)
But these small genetic changes can accumulate over time and result in viruses that are antigenically different (further away on the phylogenetic tree). When this happens, the body’s immune system may not recognize those viruses.
This process works as follows: a person infected with a particular flu virus develops antibody against that virus. As antigenic changes accumulate, the antibodies created against the older viruses no longer recognize the “newer” virus, and the person can get sick again. Genetic changes that result in a virus with different antigenic properties is the main reason why people can get the flu more than one time. This is also why the flu vaccine composition must be reviewed each year, and updated as needed to keep up with evolving viruses.
The other type of change is called “antigenic shift.” Antigenic shift is an abrupt, major change in the influenza A viruses, resulting in new hemagglutinin and/or new hemagglutinin and neuraminidase proteins in influenza viruses that infect humans. Shift results in a new influenza A subtype or a virus with a hemagglutinin or a hemagglutinin and neuraminidase combination that has emerged from an animal population that is so different from the same subtype in humans that most people do not have immunity to the new (e.g. novel) virus. Such a “shift” occurred in the spring of 2009, when an H1N1 virus with a new combination of genes emerged to infect people and quickly spread, causing a pandemic. When shift happens, most people have little or no protection against the new virus.
While influenza viruses are changing by antigenic drift all the time, antigenic shift happens only occasionally. Type A viruses undergo both kinds of changes; influenza type B viruses change only by the more gradual process of antigenic drift.”
