To the delight of volunteer Cougar Creek Streamkeepers - and herons, it has been a busy spawning season in North Delta’s most productive salmon stream.
Since mid-October, more than 300 wild coho have returned from the ocean to the creek where they began life. Returns will continue at a slower pace until late December.
A spawning female uses her tail to dig shallow depressions in the creek bottom, depositing thousands of eggs in each. After fertilization of eggs by a male, she covers each “redd” with a low mound of gravel, through which the flowing creek brings vital oxygen to eggs.
Job done, the spawners die and their final role unfolds - protein and minerals their bodies have accumulated at sea now feed and fertilize life in the creek and adjacent “salmon forest.”
When all goes well (no romping dog unwittingly destroys a redd, for example), coho alevins emerge in early spring, their yolk sacs still attached. Within weeks, they develop into tiny fry that swim in small schools, feeding on creek plankton and invertebrates.
They spend a year in their natal creek, growing to four to six centimetres, before heading downstream in late spring of their second year, to an estuary where they can adapt to saltwater in preparation for their time in the ocean (typically 18 months).
Despite this past year’s heat and drought, Cougar Creek’s 2023 spawning season looks to be a banner one. Streamkeepers hope their many stewardship projects during the past four decades – in collaboration with City of Delta, Delta School District, DFO, BC Wildlife Federation and countless volunteers - may be helping this unique urban salmon run stay resilient.
Restored streambank vegetation, gravel spawning beds, embracing beaver wetlands, rain gardens and swales – these simple tools, and more, help nature provide the healthy creeks that bring life to salmon and joy to people.
Editor’s note: For info on monthly meetings and more see www.dncb.wordpress.com and www.facebook.com/DeltaNats/.
