For quite a while there have been water quality/oxygen issues in the Canal (more than a decade). The algae are a big problem, too. Worked with a guy who had been doing a lot of algae sampling there and was convinced that there was an occasional (close to annual but not every day) bloom of a specific alga that was killing many/most of Chinook outmigrants. It was very episodic and the problem was that after the dead fish were seen the algae had been dispersed by tides. He detected the same algae in lower BC and it's abundance seemed to correlate well with drops in sockeye.

There are some major issues going on in the water and it is too expensive to monitor. Leastways that's the excuse.