South Delta Leader, 10th December 2009
Fish farms, climate eyed in salmon collapse
By Jeff Nagel - BC Local News
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.
The group of scientists who convened this week said 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 threat to the future of sockeye in the Fraser," he said.
Besides rising ocean temperatures – which can cut the food supply and expose salmon to more predators – returning sockeye may be forced to migrate up rivers that are too hot and have too little water in them.
Several of the past 15 years saw high temperatures recorded in the Fraser River, which can kill salmon or render them unable to effectively spawn.
And last summer saw both dangerously high river temperatures and extreme low streamflows in some tributaries after an extended drought.
The findings released by the scientific group show a steep decline over the past 15 years in the proportion of adult sockeye that return compared to the previous generation that spawned them.
The scientists recommend better work to assess juvenile sockeye populations at various locations in the Fraser and along the coast.
Salmon return forecasts have proven notoriously unreliable, the scientific group said, and there should be less expectation of accuracy in light of the recent trend.
The federal government this fall ordered a judicial inquiry to probe what happened to the missing salmon.
http://www.bclocalnews.com/richmond_southdelta/southdeltaleader/news/78998742.html
Fish farms, climate eyed in salmon collapse
By Jeff Nagel - BC Local News
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.
The group of scientists who convened this week said 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 threat to the future of sockeye in the Fraser," he said.
Besides rising ocean temperatures – which can cut the food supply and expose salmon to more predators – returning sockeye may be forced to migrate up rivers that are too hot and have too little water in them.
Several of the past 15 years saw high temperatures recorded in the Fraser River, which can kill salmon or render them unable to effectively spawn.
And last summer saw both dangerously high river temperatures and extreme low streamflows in some tributaries after an extended drought.
The findings released by the scientific group show a steep decline over the past 15 years in the proportion of adult sockeye that return compared to the previous generation that spawned them.
The scientists recommend better work to assess juvenile sockeye populations at various locations in the Fraser and along the coast.
Salmon return forecasts have proven notoriously unreliable, the scientific group said, and there should be less expectation of accuracy in light of the recent trend.
The federal government this fall ordered a judicial inquiry to probe what happened to the missing salmon.
http://www.bclocalnews.com/richmond_southdelta/southdeltaleader/news/78998742.html