In 2009, about 11 million sockeye were expected, but barely one million showed up, sending economic and cultural shockwaves along the coast as commercial, sport and aboriginal fisheries closed.
The disaster of 2009, which came after three years of poor returns, was seen by many as the end of salmon on what had been the world’s most productive rivers.
But then everything changed, and 35 million sockeye came streaming back to the river this summer and fall.
The Cohen Commission will focus on the decline of Fraser sockeye, not on the big run that still has the waterfront buzzing. But some of the submissions will urge him to examine the surplus of salmon in 2010 – even though that’s not his job.
One of the most interesting submissions, and the only one to come from someone with a medal named after him, has already been filed by Timothy Parsons, a professor emeritus at the University of B.C. and honorary research scientist at the Institute of Ocean Sciences.
Dr. Parsons (after whom the government’s annual Timothy R. Parsons Medal for outstanding contributions to the field of ocean sciences is named) believes this year’s amazing sockeye run is a one-off event, and that it would be wrong to take it as a sign the fish have bounced back.
The sockeye boom of 2010, he said, looks like it was caused by a volcanic eruption in Alaska, in 2008.
Relying on research done by Roberta Hamme, an assistant professor in the School of Earth and Ocean Sciences at the University of Victoria, Dr. Parsons speculates that the eruption of the Kasatochi volcano fertilized the sea, and stimulated the growth of the salmon, leading to higher survival rates.
Ms. Hamme, in a paper published in the science journal, Geophysical Research Letters, reports that a shower of iron-rich ash fell on the Gulf of Alaska after the eruption.
Using satellite imagery and oceanographic data gathered by a Department of Fisheries and Oceans vessel, she concluded the ash caused an explosion in phytoplankton, in an area more than 1000 kilometres wide.
“It’s fascinating,” Dr. Parsons said of her findings. “And it falls in line with my research.”
In the early 1970s, he led an experiment that fertilized Great Central Lake, on Vancouver Island, to see what impact it had on young sockeye. The fish grew 35-per-cent larger and the run increased from 52,000 to 373,000.
Later, he studied food chains in the sea and concluded that salmon productivity can change dramatically in the Gulf of Alaska depending on the type and density of phytoplankton populations.
He said the sockeye that returned to the Fraser this year would have been in the Gulf of Alaska at the peak of the phytoplankton bloom, at a stage in their lives when they were feeding heavily and growing rapidly. The run of 2009 would have passed through the fertilized area, too, but as mature adults headed home to spawn, and they would not have benefited much from the phytoplankton bloom.
“This extraordinary event, I think, might account for the 34.5 million return,” he said.
Dr. Parsons says the Cohen Commission should consider the issue, because if he’s right, it could point to a whole new way to manage West Coast salmon stocks, which has less to do with population dynamics and more to do with observing an array of oceanographic factors.
“To me we have to change the whole nature of fisheries research,” he said. “I’ve been saying this for a long time, but I guess it wasn’t until this volcano blew up that there had been such a good case.”
The Cohen Commission is holding hearings in Vancouver starting this week and running through December.
View the original article here
No comments:
Post a Comment