Some fish farms should be shut down to try to open up safer routes for migrating sockeye salmon, a group of fishery scientists has recommended.

The SFU think tank is also pressing for intensified research and better counting to try to pinpoint exactly where salmon are dying off in their life cycle.

“There’s basically a black hole of knowledge of what happens to these fish after they leave the Fraser and begin their ocean migration up the coast,” SFU professor John Reynolds said.

Sockeye returns collapsed in 2009, with just 1.4 million returning to the Fraser – the lowest number in 50 years.

There’s no clear explanation yet of why 90 per cent of the expected sockeye disappeared. Plenty of fry that comprise the 2009 run hatched four years earlier and it’s thought large numbers of juveniles made it to sea.

Reynolds is among the researchers who suspects they ran into trouble in B.C. waters, soon after reaching the Strait of Georgia, where sewage discharges, other pollution and fish farms all pose threats.

He said the possible infection of wild sockeye by sea lice, bacteria and viruses from farmed salmon remains “the question that will not go away.”

Removing some farms would allow researchers to test whether that strategy works, Reynolds said.

Sockeye could also be succumbing to more distant threats further out in the Pacific. They may be finding less food, catching more diseases or being gobbled up by more predators – and possibly a combination of the three.

Climate change was identified by the research group as a potential contributing factor. There’s nothing to directly tie global warming to the 2009 salmon collapse, Reynolds noted, adding it’s likely a bigger danger going forward.

“Climate change probably repesents the single largest ......

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