There is "no smoking gun" to explain the "steady and profound" decline of the Fraser River sockeye, according to the B.C. Supreme Court justice who led a two and half year inquiry into the collapse.

But in his final report released today in Vancouver, Justice Bruce Cohen lays out 75 recommendations, including the shutdown of dozens of fish farms on the sockeye migration route, if they’re found to be too risky.

In a hefty, three-volume report spanning more than a thousand pages, Cohen says that "the idea that a single event or stressor is responsible for the 1992-2009 declines in Fraser River sockeye is appealing but improbable."

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There is no smoking gun to explain the steady and profound decline of the Fraser River Sockeye, according to the B.C. Supreme Court Justice Bruce Cohen who led a two and half year inquiry into the collapse. (CBC)

Instead, Cohen says a string of cumulative factors likely played a role, such as contaminants in the Fraser River, development along its shores, and ocean conditions that may have contributed to long-term decline as well.

"Climate change and warming waters present perhaps the most daunting long-term threat to the Fraser River sockeye fishery," Cohen wrote.

DFO conflict of interest

Cohen also identified a potential conflict in the job of the federal Fisheries Department, which both promotes and regulates B.C.'s fish farms.

"As long as DFO has a mandate to promote salmon farming, there is a risk that it will act in a manner that favours the interests of the salmon farming industry over the health of wild fish stocks."

Salmon farms along the sockeye migration route in the Discovery Islands — amounting to dozens of farm sites — have the potential to introduce exotic diseases and to aggravate diseases endemic to the wild fish.

"Mitigation measure should not be delayed in the absence of scientific certainty."

Cohen recommends a freeze on new open-net salmon farm production in the Discovery Islands until September 2020.

"If by that date DFO cannot confidently say the risk of serious harm to wild stocks is minimal, it should then prohibit all net-pen salmon farms from operating in the Discovery Islands."

Cohen also took a jab at the Harper government, writing that he was troubled by the recent amendments to the environmental assessment process and the Fisheries Act, because experts he heard from emphasized the importance of protecting fish habitat.

He says it's "regrettable" the Harper government put them through without the benefit of the final report from his commission.

Cohen appointed in 2009

The report comes after Cohen held several months of hearings, collected more than three million pages of documents and heard from 179 witnesses at the $25-million inquiry.

Cohen was appointed to lead the inquiry by Prime Minister Stephen Harper after only 1.4 million of the highly prized salmon returned to spawn in 2009. Approximately 10 million sockeye were expected to return to the river that year.

The huge shortfall forced the closure of the commercial, recreational and aboriginal sockeye fisheries on the river over the summer, and raised questions about the long-term survival of B.C.'s salmon stocks.

Although only a fraction of the fish that were forecast showed up in 2009, the 2010 run saw 35 million sockeye, the biggest run since 1913. About 4.5 million returned in 2011 and just 2.3 million in 2012.

The offspring of those few sockeye that made it back in 2009 are now out in the ocean and are due to form the run for the summer of 2013.

With files from the CBC's Curt Petrovich