Bit by bit, scientists on the West Coast are piecing together reasons for the disappearance of salmon — and the devastating impact it has had on grizzlies — at Rivers Inlet on the British Columbia coat, east-southeast of the Queen Charlotte Islands.
Grizzlies in the area were gaunt at hibernation time last fall, because there were too few salmon to eat. Since they were unable to pack on winter fat, few are expected to have survived the winter. During the fall, at the native community of Oweekeno, fourteen were shot by residents and conservation officers because, without salmon to catch, and weak and desperate for food, they refused to leave the community.
Oweekeno is on the Wanuk River which flows from Lake Oweekeno to the upper end of Rivers Inlet. The lake is about 50 kilometres long, and is the centre of a watershed reaching to the Coast Mountains, a further 50 kilometres inland. Rivers Inlet is also the destination of several other rivers, and stretches 30 kilometres to the Pacific Ocean.
Thirty years ago, more than three million sockeye salmon returned to Rivers Inlet each year. It was the third largest salmon run on the West Coast. Last year fewer than 3,400 returned, and grizzlies starved.
In 1980, salmon stocks had declined so much that the federal Department of Fisheries and Oceans closed the inlet to commercial fishing for four years. Within ten years, stocks were again in serious decline and, in 1996, commercial fishing was banned indefinitely. That year, 65,000 returned. In 1997, the salmon run rebounded to 250,000. But in 1998, with the ban still in effect, it dropped to 52,000.
This much the scientists know, says Blair Holtby, head of the department’s north coast salmon stock assessment: until this past winter, when La Niña returned, there had been no upwelling of cold water in the Pacific range of the sockeye for several years.
The cold, upwelling water brings with it nutrients upon which phytoplankton feed. Young sockeye, newly emerged from the inlet, feed, in turn, upon the phytoplankton. If there aren’t enough nutrients for the phytoplankton, there aren’t enough phytoplankton for the young sockeyes, slowing their growth, and keeping them vulnerable to ocean predators. Some predators, such as mackerel, move in as the water warms.
Does this explain the precipitous drop in returning sockeye? Only in part, says Holtby. No one knows the whole answer.
What about the absence of upwelling cold water? What caused that? Again, says Holtby, no one knows for sure. It’s a complex issue, he adds, involving ocean currents, atmospheric pressures, and wind currents
Could global warming be a contributing cause? Possibly, he says, but again, no one can say, with confidence, that it is.
What is apparent, once again, is that there’s a complex web of connections, and, as the starving grizzlies demonstrated, far-reaching consequences.
I ask Holtby what he would say to urban dwellers, people in Edmonton, Winnipeg, or Toronto? Why should they be concerned about what’s happening at Rivers Inlet?
« I’d say they should care because salmon are national treasures of all Canadians, just as loons are,’’ he replies. « And it doesn’t matter if you live in Hamilton, or Wawa, or Toronto.
« I’d say that the only way to preserve this treasure is to preserve entire habitats, and that means preserving whole watersheds.’’
To often we think protection means a lot less. Protecting maybe one river out of ten, for instance. Or protecting isolated blocks of land. We have a bits-and-pieces mentality, he says, « and we’re being two-bitted to death.’’
Some salmon, he says, « a few in tens of thousands,’’ don’t return to the river of their birth. They find another river. That’s essential to maintaining genetic diversity, he says, and genetic diversity is absolutely necessary if salmon are to cope with changing environmental conditions. « So you may need all ten rivers protected, not just one.”
With changes going on that are as big as shifts in ocean upwelling, it seems to me that Holtby’s right. We do need to think bigger.