Read scientific papers thoroughly

Scientific papers are a good source of information, but they need to be read completely

Re: “Cohen commission report must be acted upon”; by Leona Adams; Opinion, Nov. 6.

Ms. Adams claims that “Provincial and federal government science proves net-pen salmon farms now pose more than a minimal risk of serious harm to the health of migrating Fraser River Sockeye Salmon.”  I disagree.

In a televised interview last April I stated that piscine reovirus (PRV) was common in BC farmed salmon but not a concern.  Ms. Adams quoted two scientific papers that seemed to dispute my assessment of PRV risk.

Scientific papers are a good source of information, but they need to be read completely and interpreted with care.

For example, the 2012 paper that she cites as evidence that PRV causes the disease HSMI also says, “PRV is almost ubiquitously present in Atlantic salmon marine farms, and detection of PRV alone does not establish an HSMI diagnosis.”  That means that without evidence of disease, the fact that fish have PRV cannot be used to prove anything about the risk to wild salmon.

Ms. Adams also expressed concern about smolts being exposed to 650 billion infectious particles per hour during an IHN virus outbreak on a fish farm.  That sounds like a lot of virus, but viruses are very small.

It would take about 11,000 years for the infected farm to release enough IHN virus to fill a single sockeye salmon egg.

More importantly, DFO research published in 1993 (Disease of Aquatic Organisms) showed that when sockeye salmon smolts were exposed to IHN-infected Atlantic salmon for 37 days, 96 per cent survived.  Also, infected sockeye salmon did not spread the virus to other sockeye salmon.

Gary D. Marty

Fish Pathologist

BC Ministry of Agriculture