The summer was harsh on salmon in and around Terrace.
Temperatures skyrocketed above 30 degrees Celsius in July and August, and the summer was drier than usual, according to Environment and Climate Change Canada. June only saw 76 per cent of the expected rainfall.
“When temperatures start to get above 18 degrees in these streams, the extra stress makes it harder for them to travel upstream,” said Kaitlin Yehle, fisheries biologist for the SkeenaWild Conservation Trust. “At above 20 degrees Celsius, it really starts to attack salmon and their survival. That’s when we start to see a lot of pre-spawn mortality, lethargic fish.”
The average temperature in July was 18 degrees Celsius, according to the government agency. August saw an average temperature of 20 degrees Celsius up until Aug. 22, cooling down to seasonal averages in its last week.
“People have witnessed salmon, dead, floating down streams. I can’t say for sure that that’s temperature related, but that probably plays a part,” Yehle said.
The SkeenaWild Conservation Trust works with government organizations — federal, provincial, and First Nations — to increase the awareness of and preparedness for this issue. But when streams reach high temperatures, there’s not much they can do other than advocate for selective fishing, Yehle said. This ensures there is no added impact on the salmon that are trying to migrate upstream.
Ballooning temperatures don’t just affect salmon, but an entire ecosystem because salmon play such an important role as a keystone species, said Yehle.
Salmon are a source of a food for wildlife like bears, eagles, and wolves. Wildlife then distribute the nutrients from salmon to forests through the carcasses they leave and when they defecate. Salmon remains act as fertilizer for a healthy forest.
While salmon have had to contend with wildfires and getting isolated from streams in the past, this kind of disruption to their life cycle is happening more frequently.
“Fish have to adapt and evolve to these things,” Yehle said. But can they evolve this quickly?”
There can be some positive outcomes to changing habitats, however.
“New habitats are opening up for salmon that they didn’t use before,” she said. “One thing that’s really key for protecting salmon in the future is protecting a diversity of habitat. So not necessarily just where we see them now, but where we might anticipate salmon in the future, as different habitats open up."
Yehle shared that the local community can help out as well. If a stream level is too low, salmon can be stuck in pools and unable to get back to the stream. Yehle said to call the DFO hotline number at 1-800-465-4336.