For the first time in at least half a century, chum salmon have returned to Vancouver.
There have been efforts to clean up the heavily polluted Still Creek, which flows from central Burnaby to east Vancouver, going on for a few decades.
In early November, chum salmon returned to the creek and have swam as far up as the Renfrew ravine, marking the first salmon in the city of Vancouver for “at least half a century,” according to one expert.
“Sometimes a salmon’s olfactory memory isn’t as sharp and they’ll stray off, accidentally sort of stumble in there and colonize a new habitat,” said Ken Ashley of the Rivers Institute at BCIT.
Ashley explained over the phone how the salmon could have possibly known to swim through Still Creek to spawn after so many decades.
Ashley said that chum salmon use their sense of smell to follow the same spawning route year after year. If those routes are disturbed in some way, though, they are able to use their sense of smell to find another stream suitable for spawning that may have been used decades ago like Still Creek.
“It’s a good evolutionary device for salmon to have,” said Ashley, who said it’s useful in cases where a stream becomes flooded by rain or dammed up by humans.
Another explanation for the chum’s return to Still Creek is fish hatcheries that stock streams with chum fry and eggs from fish hatcheries in order to introduce them into a wild habitat.
What was once the Lower Mainland’s most polluted waterway is now home to one of the most amazing spawning habits in the animal kingdom. The high school biology geek inside me is stoked.