How many farm critics here actually read the study? Or did most just default to the red meat media version? I think for most it was the latter. Shocker.
The BC Salmon Farmers press release makes some good points, but one just has to read the study to find out that the claims made are sketchy at best. First, it was a very poor sample size with very unequal representation. Look at the raw data provided to see where the samples were from within the Fraser watershed - those upstream and downstream of Hope. Most are downstream of Hope. Look at the data in the columns. Of course infection rate is greater in the lower regions if that’s where most of the samples are from. Within those catch areas the fish could have all been handled differently if caught by recreational anglers and First Nations. In order to make broad population inferences one should do a more extensive, structured surveillance of wild salmonids which the authors admitted was lacking in their study.
Second, the authors categorizing of “significant migratory challenges” is too vague and incomplete and doesn’t address WHAT THE ACTUAL ENVIRONMENTAL CONDITIONS WERE AT THE TIME. Nowhere in the study do the authors put context to their findings by saying what the Fraser River conditions were during the sampling period in 2012 and 2013. Also, those conditions can change within the migration from month to month, from run timing group to run timing group. For instance, Early Stuart Sockeye can typically face some significant migratory challenges in some years through Hell’s Gate in June and July due to much much higher discharge following spring freshet. Early Summer to Summers Sockeye can experience higher water temperatures some years, but Late Summer Sockeye can avoid those late on in September and October.
In a nutshell, there’s variability. But what might be a major migratory difficulty one year might not be so much the next. Yes, places like Hell’s Gate and the other migratory bottlenecks can be difficult places for salmon migration, but it depends on what the river discharge and water temperatures are at the time. Pacific salmonids have water discharge and temperature thresholds where migration can be difficult, but not so much below those levels. Some years had very high water temperatures in the Fraser but that didn’t necessarily translate into major prespawn mortality. Instead, the authors make it black and white (i.e. challenged or not) which in reality isn’t what its really like.
Third, what are these PRV infected salmon relative to what actually escaped to the spawning grounds in 2012 and 2013 if we are looking at the adult samples. In 2013, some Fraser CUs that escaped to the spawning grounds did better than cycle year averages. Yet the authors claim that PRV infected salmon could be experiencing migratory difficulties due to bad hearts. Well the spawning ground escapements for many CUs don’t appear to corroborate those claims in both 2012 or 2013. Can’t take the number of samples they did and start making those claims - especially at the population level. Statistics are great but they should be ground truthed.
Lastly, HSMI has not been documented in wild salmon in BC or even in Norway. The authors even state:
However, HSMI has not been reported in wild or captive Pacific salmon.
How many of the samples in the study were examined for HSMI? Apparently, PRV is this very deadly virus to wild Pacific salmonids and no testing for the disease, HSMI. I know the answer why not and so do you.
Happy Holidays!
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Topic: Get your facts straight? (Read 1685937 times)