DFO investigating krill die-off

Large blooms of phytoplankton the likely cause

Scientists with the Department of Fisheries and Oceans (DFO) suspect depleted oxygen levels caused by large blooms of phytoplankton is the likely cause of a recent die-off of krill in local waters. 

People out at beaches in the Selma Park area recently reported seeing thousands of dead krill, which look like small shrimp, washing up on the shore. 

article continues below

Ian Perry of DFO’s Pacific Biological Station in Nanaimo told Coast Reporter via email that krill are common and usually very abundant along the east side of the Strait of Georgia around Sechelt, Malaspina Strait and Jervis Inlet. 

“These sorts of large die-offs of krill are not common, but they do occur naturally,” Perry said. “They are usually caused by large blooms of phytoplankton which sink to the bottom and use up much of the oxygen there … causing oxygen stress to animals living at those depths, which is where the krill usually live during the daytime.” 

Perry said there was a similar event in the Irvines Landing area in the first week of April last year. 

“We had one of our DFO survey vessels in Malaspina Strait a week or so before this incident,” he said. “We observed 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.” 

There was also a DFO survey ship in the Sechelt area on March 17 and the crew saw evidence of phytoplankton blooms. 

“That ship came back to port last Friday [March 20], and we are beginning to analyze the data,” said Perry. 

Perry said the oxygen depletion is short-lived, but lasts long enough to harm krill before returning to normal after a few tidal cycles. 

“A member of the public has collected some samples for us, which we will examine once we can get them shipped to our labs,” he said. 

© Copyright Coast Reporter


NOTE: To post a comment you must have an account with at least one of the following services: Disqus, Facebook, Twitter, Google+ You may then login using your account credentials for that service. If you do not already have an account you may register a new profile with Disqus by first clicking the "Post as" button and then the link: "Don't have one? Register a new profile".

The Coast Reporter welcomes your opinions and comments. We do not allow personal attacks, offensive language or unsubstantiated allegations. We reserve the right to edit comments for length, style, legality and taste and reproduce them in print, electronic or otherwise. For further information, please contact the editor or publisher, or see our Terms and Conditions.

comments powered by Disqus