David Marmorek, an expert on aquatic ecology and simulation modeling, has analyzed all the technical evidence put before the Cohen Commission and has concluded that while no "primary cause" of the great sockeye salmon collapse of 2009 exists, the most likely explanation is the fish died at sea.
Mr. Marmorek, whose work is likely to guide the final report of the British Columbia Supreme Court's Mr. Justice Bruce Cohen, said a major research effort will be needed to fill in the "data gaps" that exist concerning what happens to salmon after they leave the river and before they return to spawn.
"The ability to assess the exposure of Fraser River sockeye salmon to various potential stressors in the open ocean and return journey to B.C. coastal waters is severely limited by [a]lack of knowledge," Mr. Marmorek's report says.
He quoted one researcher as saying "there are virtually no observations of Fraser River sockeye salmon during about 75 per cent of their life at sea."
Shortly after he was appointed to head the inquiry into the decline of Fraser River sockeye, Judge Cohen commissioned 12 scientific reports to examine everything from the impacts of salmon farms to the effects of climate change on salmon stocks.
Those studies are now in and Mr. Marmorek, president of the environmental consulting firm ESSA Technologies Ltd., was given the task of heading a team that synthesized what the reports found.
"They get eaten … they die of starvation … as to exactly what kills them? No, we don't know that," Mr. Marmorek testified on Monday, in discussing the cumulative findings.
The Cohen Commission was appointed by Prime Minister Stephen Harper after the sockeye run collapsed in 2009, causing the third complete fishing closing in as many years. But just after Judge Cohen began his investigation the Fraser had a banner year, with stocks bouncing back to historic levels in 2010.
Mr. Marmorek said the dramatic turnaround appears to be linked to oceanic conditions, but it does not signal an end to nearly two decades of sockeye declines.
"We were dealt a nice hand in 2008 [when the sockeye that returned in 2010 were at sea]… that doesn't mean you'll get a good hand in the next game of poker," he said.
Mr. Marmorek's report concludes that while the scientific studies done for the Cohen Commission do not point to any single cause, the most likely explanation is that something went wrong in the Strait of Georgia, Queen Charlotte Sound and the Gulf of Alaska, where the young sockeye feed and grow.
He said there is intriguing research pointing to the role of sea temperatures, phytoplankton levels and ocean salinity, among other things, but much more research is needed.
"Since the early marine environment appears to be a major potential source of declining productivity, it is particularly important [to]improve information on potential stressors affecting sockeye along their migratory path from the mouth of the Fraser River through Queen Charlotte Sound," his report states.
Mr. Marmorek calls for a "fully integrated" investigation involving both the Canadian Department of Fisheries and the U.S. National Oceanic and Atmospheric Administration.
His said no conclusions are possible about the role of pathogens, because almost no data exist on diseases.
Mr. Marmorek also said a science report on the impact of fish farms had resulted in such "strongly polarized opinions," that it isn't possible to reach any clear conclusions. While Dr. Donald Noakes found "salmon farms pose no significant threat to Fraser River sockeye salmon," Dr. Lawrence Dill reported "the greater the farm production, the lower the survival of the sockeye."
Mr. Marmorek recommended a working group, rather than one individual, be struck to continue examining the fish farm issue.
The Cohen Commission is entering its final phase, with evidentiary hearings to conclude next week. Closing summaries from participants are expected in November, with a final report due next year.