Heavy rainfall, slow snowmelt helps marine life thrive in B.C. rivers, waterways

Freshwater scientists and biologists in B.C.'s Cowichan Valley say marine life in the area is thriving this spring, with the combination of heavy rainfall and late spring thaw resulting in higher water levels in rivers and other waterways.

"For river levels, generally at this time of year we like to see ... seven to 15 cubic metres per second. This year, we're running about 30," said Tom Rutherford, the executive director of the Cowichan Watershed Board.

He said in his 30 years of experience, he's never seen water levels this high.

"In the last 20 years or so, we've been seeing really low spring flows which is really problematic for our salmon juveniles," Rutherford told CBC News. "But when the waters are high like this, they can swim downstream."

Several communities in the province have been on flood watches and evacuation alerts this week, with heavy rainfall and snow melting from the mountains.

Rutherford said the salmon are thriving from the high water levels along with the cooler than average temperatures.

"This year, those big fish can just kind of paddle right up to the lake and spend the summer there and then fall back down into the river and spawn in the fall," said Rutherford.

According to the program manager at Redd Fish Restoration Society in Ucluelet, temperature helps dictate growth, movement and metabolism in fish.

"That stuff is controlled by temperature and it dictates the whole season, like when they come out of the gravel and when they start their migration," said Tom Balfour. 

He said higher river levels also help protect marine life from predators as it's harder to catch them when there's more water in the river.

"Generally the more water that's in the river, there's just more space and it's harder to catch young fish because there's more nooks and crannies for them to hide," he said.