Spring, Salmon and the Mighty Skeena River
Dec 9, 201
By Sam Wilson
As Canadians, we get excited about spring. Every February 2nd we wait with bated breath to see if the local groundhog will pronounce only six more weeks until spring, and inevitably the first robin will have my mom stating that spring is finally here – despite the two feet of snow on the ground. Spring is an exciting topic for scientists too. But for much different reasons.
Spring is getting earlier. And while this may have some folks smiling, it’s anything but a happy conversation for those of us that study spring. The problem? Animals, especially those that migrate or hibernate, are having trouble keeping up with their quickly-shifting food supply. For example, the spring-signalling American robin is arriving earlier from its winter breeding grounds, but if its egg-laying date doesn’t sync with the food supply, its chicks might starve. A similar story might be happening beneath the waters of our rivers in the Pacific Northwest. Cue - my research.
I study the migration of juvenile salmon as they make their way to the ocean in the spring. Juvenile salmon must time their entry to the ocean just so, in order to take advantage of the spring plankton bloom and grow the fastest. But the spring plankton bloom is advancing rapidly with climate change. Can salmon keep up with advancing spring? If they can’t, will they survive?
Different populations of salmon may be more vulnerable to a changing spring if they have different amounts of energy stores when they reach the estuary? To measure energy stores of different populations along their migration route, I worked with collaborators up and down the Skeena River to collect sockeye salmon smolts. Which was why in late May this past year, I found myself on a jet boat bombing up the milk-chocolate coloured mainstem of the Skeena River near the confluence with the Kispiox River.
Above the water on that warm spring day it was hard to fathom the tens of millions of fish migrating past us to the ocean. It was hard to believe that we would catch anything at all, mid-day in this frothing river. But the first time the fisheries biologists from Gitxsan Watershed Authorities dragged the net to shore, there they were! A dozen silver-sided skinny little salmon! We collected DNA samples which tell us where the smolts came from, measured, and froze some smolts to bring back to the lab and examine energy storage. As I left the river, I said a silent goodbye to all those invisibly migrating baby salmon. The next time I would see them is when they returned – not as skinny little silver-sides but as the 70cm-long bright red beauties that will have the countryside swooning.
As I continue my research I have a new reason to anticipate spring. Excited to see them again, my little silver-sides. Hoping that they will return as adults. Eagerly awaiting the data to answer my question – will salmon survive a changing spring?