Running With The Crowd
By Mary Jane Schramm
She’d been living large since leaving the stream where she hatched three years earlier to join the fish-licious feast in progress just beyond San Francisco’s Golden Gate. This spring, strong, pulsed winds had created superb conditions for feeding in Greater Farallones National Marine Sanctuary, and she had gorged, along with whales, sea lions and sea birds, on small fish and invertebrates. Abundant krill, tiny pink shrimplike crustaceans, would lend her flesh a rich rosy tone and sustain her on an arduous journey. The eggs she carried within her were ripe, and instinct compelled her to seek out her natal stream to spawn and complete the cycle of life. So, she sought out its familiar smell, little knowing how important to her species her success would be.
Half & Half: Coho salmon (Oncorhynchus kisutch) inhabit coastal streams and ocean waters over the Continental Shelf across the North Pacific. Anadromous fish, they spend half their life in rivers and streams where they were born, and half their lives at sea. Adults migrate upriver to their birth streams, where the females dig out numerous nests, or redds, in gravelly stream beds, and lay thousands of eggs. An attending male, sporting spawning-season attire - fiercely hooked jaw and sharp teeth - deposits his milt, or sperm over the eggs.Having fertilized them, his work is done.
Spawning cohos require clean, cool, running freshwater streams. Stream flow must be sufficient to aerate developing eggs and embryos, and side channels and inlets are needed to shelter the young as they feed and develop. Passing from egg to tadpole-shaped alevin, to fry (as in “small fry”), then as smolts heading downstream, they’ll target estuarine and marine waters of the Pacific Ocean to forage and fatten as adults.
Timing is Everything: Just over two decades ago, habitat degradation from logging, dams and agricultural water diversion, overfishing, drought and other causes pushed Central California Coast coho to the edge of extinction. The National Oceanic and Atmospheric Administration (NOAA) declared the region as critical habitat in 1999, and in 2015 initiated stronger measures to conserve them. The California Department of Fish and Wildlife, and various non-profit groups joined the effort to save the salmon. In Sonoma’s Russian River, hatchery programs have aided in their recovery.
Recently, the coho salmon population at Lagunitas Creek in Marin County, made a strong return. Last winter’s storms, occurring at critical times, may have mitigated the ongoing drought’s low stream flow problems. Lagunitas experienced one of the best salmon runs in recent years, with 330 coho egg nests, or redds: a near record. Ideally, they will return as adults in the winter of 2023-24, but the abrupt dryness early this year may have jeopardized young salmon remaining in freshwater habitats.
Dark Clouds? Climate change is increasingly recognized as an emerging bar to ensuring these salmons’ recovery, in addition to challenges noted above. Now-chronic above-normal temperatures create extra warm, oxygen-poor river and stream waters. Wildfires have destroyed valuable riparian (riverside) habitats, while burned-off ground cover has increased stream sedimentation, especially when heavy winter storms generate mudslide runoff. Together they contribute to impaired water quality, increasingly salmon-unfriendly.
Hope & Help! In the end, conservation efforts such as those noted above, will determine if the Central California Coho salmon survive and thrive. Faced with such challenges, the agencies, organizations and individuals addressing the issues will be stepping up efforts to meet them. But, with effective networking, effort, and determination, it can be done. Dam removals and better riparian corridor management, are actionable parts of the equation.
Learn what groups are active in your community, and consider lending a hand to help this iconic species continue to survive and grace our rivers, streams and ocean. And for a lighthearted perspective on the Russian River, host to coho and Chinook, see https://www.fisheries.noaa.gov/feature-story/interview-habitat-river.
Left, top: Coho Salmon male. Photo: BLM.
Middle: Coho Salmon Quilcene Hatchery-USFWS.
Bottom: Coho Salmon Spawning. Photo: NPS.
