Chris Moss

We have always marvelled at the return of the Pacific Salmon to the rivers on Vancouver Island.  Both Indigenous and Settler communities have made use of this great natural resource.  It is one of the biggest annual migrations on the planet and it occurs all up and down the west coast of North America.

Often we hear of the Salmon in the Sooke basin waiting for the right amount of fresh water and temperature to begin the journey up the Sooke River to spawn. Is it my imagination that the fish have had to wait longer and longer for the right conditions to occur?  Is there something else happening due to Climate Change that is changing their behavior?

 I listened to a webinar recently from the UVIC research group POLIS (A Greek word meaning Community) One of the researchers gave a detailed review of his ongoing Doctoral work on the health of BC salmon stocks based on the availability of water resources in the province.

Salmon like cold water, for example. In one study he found that in a lake with two water sources, watershed runoff on one side and glacial run off on the other, fish would choose the cooler side of the lake.  Which is fine except we are losing all of our glaciers due to a warming climate and the reduction in cool clean water will affect the health of the fish stock.  In general, he found that salmon migrations and river returns are moving northward up the BC coast. 

The last set of data that the scientist from UVIC presented was on stream flows on Southern Vancouver Island to the year 2100.  He extrapolated his data to four endpoints based on the estimated increase in global temperature from 1.5 degrees Celsius to about 4.5 degrees Celsius.  He noted that the most recent data collected was showing that we were already moving toward the most extreme end of the model.  By the year 2100 he said it was most likely that all the streams on Southern Vancouver Island will be dry for the summer period.  This would make it impossible for the fry salmon and riparian life dependent on the stream to survive.  It would require waiting until late early November for the rivers to receive the Winter rainfall enough to enable spawning to take place.  Salmon will have to adapt to the new cycle, and if they cannot, salmon stocks will likely collapse. Already the CRD provides the Sooke River with additional water to aid the salmon to return. We don’t know if that will be enough in the future to maintain the spawn and bring the salmon up river.

The boom and bust rainfall cycle we have seen in the past few years are now expected to continue and intensify as climate change runs out of control.  Rain, perhaps more than average amounts, in the Winter followed by longer dry periods in the Summer.  Eventually we may have only two seasons, Wet and Dry.

The shock of this information is greater when we realize that a 1.5 degrees Celsius rise by 2100 will result in dry creeks and streams and what rivers are left will have drastically reduced water flow.  At the most extreme level of temperature rise he estimated that these conditions will occur by 2075 or earlier.  The child born this year will only be 50 years old when this future becomes a reality.