“As the system gets changed, salmon are having to cope with that impact,” said Dr. Moore, a professor of biological science and resource and environmental management at SFU, where he holds the Liber Ero Chair of Coastal Science and Management.
In some river systems, they’re starting to die.
Changing food web
The life cycle of salmon is timed to the life cycle of other species upon which they rely for survival. As these ecosystems change, the timing of the food web is changing, Dr. Moore explained.
For example, if young salmon migrate to the ocean when the food web is right, they survive. If their timing is off, they are more likely to die.
There is good news.
The lab compiled data on when salmon along the North Pacific coast are migrating to the ocean and found that salmon are adapting, migrating earlier or later in response to the changing climate.
The life cycles of those ocean species are also changing, though. The question is whether they are changing more rapidly than the salmon that rely on them.
The return to freshwater to spawn is another key part of the salmon life cycle.
Another study by the lab gathered spawning data from California to Alaska and found a wide range of spawning, from June and July to November and even February. Salmon have already started to adapt to warming water temperatures in summer, Dr. Moore said.
In B.C., we can expect to see the time of salmon life cycles shift in the coming decades.
“They’ve coped with amazing challenges over their evolutionary lifetime and they’ve found solutions,” he said.
Not just global warming
These challenges are coupled with other stressors, from mining and forestry to overfishing and the dangers of open net-pen salmon farming.
Rising sea levels, coupled with coastal development are putting a coastal squeeze on habitat.
Flood control infrastructure in areas like the Lower Fraser region have cut off habitat. Work like Connected Waters – Watershed Watch’s campaign to reconnect 1,500 kilometres of salmon habitat blocked by outdated flood infrastructure in the Lower Fraser floodplain – is helping.
There are agricultural and forestry pressures, land use and water use decisions, all of which have immediate and direct impact on salmon habitat and salmon survivability.
Overfishing, like the devastating interception fisheries in southeast Alaska, continue and there is a growing body of scientific evidence of the harmful effects of open net-pen salmon farms on wild salmon populations.
“It’s just one more hammer on salmon populations,” Dr. Moore said. But “there is some exciting action happening in terms of getting some of these salmon farms out of some of those key migration pathways.”
While glacial melting is affecting salmon habitat it is also creating new habitat, particularly in northwestern B.C., where new stream beds appear as the glaciers recede. The problem is that these newly exposed stream beds create new mining opportunities, which can have a detrimental effect.
Dr. Moore worries wild salmon are suffering a death by a thousand cuts. He would like B.C. to have legislation that considers cumulative effects, rather than looking at individual impacts in isolation.
“Salmon are resilient. They’ve adapted to a lot over their lifecycle, and they do have the capacity to cope with change,” he said. “There’s a lot we can do.”