For the past few months, folks in Vancouver have been gathering under the Cambie Bridge to watch migrating salmon.
The film-art installation, called Uninterrupted, brings the heart of a wild salmon-bearing river to the heart of the city. Its creators filmed salmon moving up and down B.C.’s rivers over the course of four years. The resulting 30-minute spectacle projects the images on the bridge’s underside.
The irony is that the sockeye runs in False Creek and the Fraser River have been dismal this year. Anticipated to be an improvement over last summer’s record-low jockey salmon returns on the Fraser River, this is the second year in a row when sockeye fishing on the river has been curtailed.
The fishery was closed in July based on low returns for the early Stuart River and early summer Fraser River runs. Later runs have not improved.
River temperatures are also abnormally high this summer. Last year, the Pacific Salmon Commission measured Fraser water temperatures to be 20.6 C in mid-August — 2.5 C warmer than average for the time of year.
Air temperatures across southern B.C. have been higher than last year, with many new records set. B.C. Hydro reported the year’s record power use on Aug. 28, for air conditioning amid the summer 2017 heat wave.
Those sizzling air temperatures bode ill for this year’s salmon. As cold-water fish, salmon start to die when water temperatures go above about 18 or 19 C.
At least, Fraser River stocks needn’t battle drying rivers, as late-summer Cowichan River salmon do. Last year, when river levels reached critical lows, volunteers stepped in to help salmon migrate upstream. Many salmon were trapped in pools along the riverbed with no watery way to escape.
Volunteers moved thousands of fish upriver, but many more fish would have been missed.
Biologists also point to the ocean anomaly that sat off our coast for the past few years as a further complication in the health of this year’s wild salmon stocks. First detected in late 2013, the Blob — an unusual, massive mass of warm water that sat about 200 kilometres off the coast — grew throughout 2014 and 2015 to stretch from Alaska to northern California, and re-emerged last September after having appeared to have dissipated earlier.
Early this summer, researchers announced that it was gone … for the time being.
At its peak, the mass pushed cold Alaskan water three degrees above its normal chilly temperature. The warmer waters attracted animals that favour warm waters to northern, normally chilly latitudes. These marine tourists included thresher sharks, ocean sunfish and acres of velella — a sea creature related to the Portuguese man o’ war. The Blob might have also fuelled a toxic algal bloom that stretched along the entire northwest coast, affecting fishing seasons for sardines, anchovies, crabs, oysters and razor clams.
But the Blob, created in part when upwelling of cold waters from the deep ocean was suppressed, also contained little food to support marine life. The upwelling waters bring up nutrients critical to coastal ecosystems. Without the nutrients, populations of plankton and zooplankton in the northeastern Pacific Ocean became depleted. And, without enough of those microscopic creatures to support the rest of the coastal food web, thousands of California sea lions, Guadalupe fur seals, common murres and Cassin’s auklets starved along the coast.
As for salmon, catches up and down the coast in 2015 and 2016 fell. Without an abundant buffet of zooplankton to feed on in their normal migratory waters, the fish had to seek food farther afield. During the increased time spent between leaving their home rivers and finding friendlier habitat, salmon fry would have been at greater risk of disease, predation and starvation.
Even if the Blob doesn’t re-emerge anytime soon, we will likely continue to see its effects on salmon until 2020.
Next year’s sockeye runs are expected to be better on the Fraser River. Sockeye that hatched in 2014 — a good year — and found their way down their home streams and rivers to the ocean will be returning to lay eggs for the next generation of sockeye.
That is, if they escaped the effects of the Blob while out roaming Pacific Ocean currents.
