POWELL RIVER, B.C. – The cause of a massive die-off of Krill off near Powell River may never be fully determined.
This is according to a scientist with the Department of Fisheries and Oceans.
“We have tried to get samples – they may still arrive but it is likely too long since the incident occurred for any samples to be useful to make definitive statements about any causes of this event,” DFO scientist Dr. Ian Perry said in the email to the MyPowellRiverNow.com newsroom.
The die-off was first discovered along the shoreline just southeast of the Beach Gardens Resort and Marina on March 27. A post by Powell River resident Darlene Williams stated that she saw what appeared to be “1000 dead baby prawns.”
Perry said these sorts of large die-offs are not common, but they do occur naturally.
“They are usually caused by large blooms of phytoplankton which sink to the bottom and use up most of the oxygen there, as a result causing oxygen stress to other animals living at those depths (which is where the krill usually live during the daytime),” Perry stated in the email.
According to Perry, the DFO had one of its survey vessels in Malaspina Strait (off Powell River) a week or so before this incident was observed.
“We found a large bloom of phytoplankton at that time which reinforces the theory about this phytoplankton bloom settling to the deep depths and using up the oxygen there,” Perry said.
“This depletion of oxygen is a short-term event, lasting just long enough to cause damage to the krill. The oxygen concentrations will return to normal after a few tidal cycles refresh the water.”