It appears as though the culprit in this case was likely a toxic algal bloom. Nothing wrong with Alexandra Morton asking questions about why these farmed fish from Greig were dying; in fact 3 of the 4 were not bad questions,
but the problem that I have with her letter is that while she is asking questions she is coming up with her own conclusions by very passively throwing in things which could very well be red herrings.
Her own analysis of the situation is suspect at best. Morton does a plankton tow for 10 minutes and says that the water was quite clear, no sign of a heavy algae bloom, but never mentions that the bloom could have mostly dissipated by the time she arrived to do her "sampling" (no real details provided). She even said herself in her letter that this this has been going on for weeks. In her follow-up post there doesn't even seem to be a V8 moment where she even considers the possibility of a toxic algae bloom. There is not even an understanding of distribution or occurrence of these toxic algae blooms nor the environmental conditions that come into play to make it happen. Did she care to take a look at the current literature regarding toxic algae blooms off our coast? The occurrence of these algae blooms was brought up in testimony at Cohen - where Morton was a participant. If she wasn't so focused on aquaculture she would likely have a better understanding of other factors involved.
In my opinion, the letter was primarily meant to try to embarrass Greig instead of seeking information, but it was also meant to regain some of the spotlight that has shifted away from her since Cohen. In her letter she said, "Your staff onsite were very professional", well....maybe Morton's letter should have been a little more professional.
http://www.seafoodnews.com/Story/938467/Plankton-bloom-kills-off-40000-farmed-Atlantic-salmon-at-Griegs-Vancouver-Island-operationGood study for some background information on
Heterosigma akashiwo:
http://www.sfu.ca/grow/science/resources/1288805500.pdf