Monster Seminar JAM- Harmful Algal Blooms and Possible Effects on Fraser River Sockeye Salmon
Dr. Jack Rensel, Rensel Associates Aquatic Sciences
Recruit per spawner of Fraser River sockeye salmon has declined precipitously over the past 20 years and in recent years total run size has reached record low levels for our modern era, despite more than adequate escapement of many stocks. Although in-river mortality of returning adults is a problem, much of the recent decline has been attributed to unexplained marine mortality. Ten years of weekly algal bloom monitoring data by the B.C. Harmful Algae Bloom Monitoring program within four regions in British Columbia, from southern Strait of Georgia to Queen Charlotte Strait, were compared to marine survival data for the only sockeye stock that has smolt outmigration monitoring (Chilko Lake). For juvenile fish and timing, there was a modest inverse correlation between survival data and bloom intensity/duration of the fish-killing alga Heterosigma akashiwo in the southern Strait of Georgia. In particular, Heterosigma blooms in 2006 and 2007 were much earlier and extensive than normally observed in prior years and fish kills of farmed and wild fish were recorded in North Puget Sound along with warmer-than-normal water temperatures. These early blooms possibly affected juvenile sockeye outmigrating in May and June. Run sizes for these juveniles as adults two years later, in 2008 and 2009, were near record lows.
Date and Time:
January 21, 2010,
11:00 am - 12:00 pm