Coho salmon have been in the news lately, including the last issue of Yodeler. The number of salmon in Redwood Creek and elsewhere on the California Coast has dropped to alarmingly low levels.
The National Park Service (NPS) appreciates the public’s interest in the status of Redwood Creek salmon and what can be done to reverse their decline. As part of our stewardship mission we have been actively involved for several decades in working to protect and improve coho populations in the Redwood Creek.
Why have the salmon numbers dropped so low? The absence of progeny of the class of 2007-08 was the subject of the article in the December-January issue of the Yodeler, titled “On the brink: Is it too late to save the salmon of Redwood Creek in Muir Woods?” The reasons are complex, and require an understanding of the salmon life cycle.
Coho salmon are anadromous and generally spend one year in streams before migrating to the Pacific Ocean, to rear for another 1.5 years. Adults return to their streams of origin generally as three-year-olds, with little mixing among different year classes. During their lives, salmon are vulnerable to condition changes in the ocean and stream habitats. A study by National Marine Fisheries Service found that there was a 73% decline in coho salmon adults returning in winter 2007-08 to California streams due to unfavorable ocean conditions, particularly warm, low nutrient water that leads to lower food production. Almost no coho returned to Redwood Creek that year. When populations drop to extremely low levels, they are at a much higher risk due to inbreeding and unfavorable environmental conditions such as the droughts and extreme flood events that have characterized the past several years.
Since the early 1990s, the NPS has worked to improve habitat conditions for salmonids in the Redwood Creek watershed. While much of the watershed is in public ownership and managed by agencies and organizations with strong resource stewardship interests, there is a legacy of past land management activities including stream channelization and instream wood removal that reduced the natural capacity of the creek to support salmon.
In the early 2000s, the NPS participated with various stakeholders to develop a framework for habitat protection and restoration, including salmonids, at watershed and site-specific scales. We moved facilities away from drainages, added fencing to protect riparian habitat, and reduced adult salmon passage barriers. Several restoration projects are completed including instream and floodplain restoration at Muir Beach. We are working with other resource agencies and the water provider for the town of Muir Beach to improve summer instream flows for fish. Current projects include a captive rearing and release program to “jumpstart” the coho population, stream water quality assessment, and continued long-term monitoring of salmon and habitat conditions.
We have partnered with the California Department of Fish and Wildlife (CDFW) during the past two decades on this project. Gail Seymour, CDFW Supervisor, put it this way: “The NPS commitment to watershed restoration is a critical part of species recovery efforts in Redwood Creek as well as the overall Central California Coast coho salmon region.”
Helping the coho survive in Redwood Creek will take a concerted effort by resource agencies and the public. For those interested in helping, there are several winter volunteer opportunities. Visit http://go.usa.gov/zRVx to learn more.
— Darren Fong, Aquatic Ecologist, Golden Gate National Recreation Area