The long-awaited report about declining Fraser River sockeye stock during the past two decades was released Wednesday, but the findings couldn’t narrow down a main cause for the drop.

“The idea that a single event or stressor is responsible for the 1992 to 2009 decline in Fraser River sockeye is appealing but improbable,” wrote report author Bruce Cohen, a B.C. Supreme Court justice.

“Factors in the marine environment appear particularly implicated in the broad-based regional decline of salmon stocks. Regrettably, that is as far as the evidence takes me.”

The report also cautioned that the 2010 and 2011 rebound of adult salmon returning to spawn — based on preliminary data — was not complete evidence that stocks have returned to historic levels.

The numbers from the previous two years show levels similar to what was seen in the 1950s, a drastic improvement from the all-time low in 2009.

“The year 2010 was one of abundance: 29 million sockeye returned to the Fraser River,” Cohen wrote.

“However, while demonstrating the sockeye’s capacity to produce at historic levels, this dramatic improvement in a regular peak year in the four-year life cycle of sockeye did not point to a reversal of the long-term decline.”

Among the commission’s 75 recommendations, it’s asked the government to balance farmed salmon and its wild counterpart, and suggested there’s a risk the Department of Fisheries and Oceans would “favour the interests of the salmon-farming industry” over wild stocks.

It also recommends better monitoring of fish health, including minimizing risk that farmed salmon could introduce “exotic diseases” and cause serious or irreversible damage.

The full report can be found at cohencommission.ca.