From the Globe & Mail – March 11, 2011

by Mark Hume

A federal judicial inquiry that is trying to find out why sockeye
salmon in the Fraser River are in decline has been told that whatever is
killing them, it is not one of the usual suspects.

While mining,
logging, hydro projects and other industrial developments in the
watershed are degrading habitat quality, none of them can be blamed for
the precipitous drop in sockeye stocks, states a science report done for
the Cohen Commission of Inquiry Into the Decline of Sockeye Salmon.

Marc Nelitz, lead author of a study that looked at the impact of a
variety of human activities, said while the number of adult sockeye has
dropped dramatically over two decades, the survival of juvenile salmon
has remained stable.

“The collection of all that evidence leads us
to conclude it’s unlikely the freshwater environment is playing a
role,” Mr. Nelitz said Thursday, testifying to the Cohen commission.

The
report did not reach a definitive conclusion, but Mr. Nelitz said “the
weight of evidence” clearly indicates whatever is killing the fish is
doing so outside the Fraser environment.

“Based on the evidence it
seems most likely that changes in the physical and biological
conditions in the Strait of Georgia have led to an increase in mortality
during marine life stages,” the report states. “Specific mortality
agents include lack of food, freshwater and marine pathogens, harmful
algal blooms and other factors.”

The report did say it is possible
“a non-lethal stressor in the freshwater environment is causing
mortality during a later life stage,” but if so, it wasn’t identified.

Mr.
Nelitz, a systems ecologist with the environmental consulting firm ESSA
Technologies, said the research team looked at the impact of forest
harvesting activities, the effect of a massive pine beetle infestation
that has altered hydrology by killing off vast tracts of forest, the
storage of log booms in the estuary, large- and small-scale hydro
projects, urbanization, agricultural development and water use.

It
has long been known those activities degrade fish habitat to varying
degrees – but the relatively steady survival rate of young salmon in the
Fraser eliminates them all as suspects in the mystery the Cohen
commission is trying to unravel.

Bruce Cohen, a British Columbia
Supreme Court justice, was appointed by Prime Minister Stephen Harper
after only about one million sockeye returned to the Fraser in 2009,
when more than 10 million fish had been expected. That marked the low
point in 20 years of decline, although there was a dramatic and
unexpected rebound last year, when more than 28 million sockeye
returned, providing the biggest run since 1913.

The Cohen
commission, which has ordered a dozen scientific reports and is holding
evidentiary hearings in Vancouver, is trying to figure out why sockeye
stocks are so unstable, and why they have been declining for so long.

Mr.
Nelitz said the study did not look at the cumulative impact of
activities along the Fraser, nor did it examine saltwater habitat. Those
issues are under separate study.

The report said more information
is needed on the early life stages of salmon, and it called for better
estimates of juvenile abundance, for more information on the survival
rates of young salmon over winter, and for studies on the period when
smolts migrate down the Fraser and go out to sea.

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