Coho salmon are also known in English as "silver salmon" or "pacific salmon" and by a variety of local names by the Native Americans along our north coast. They are one of three common species of anadromous salmonids in Mendocino County. Anadromous fish are those that are born in freshwater and then migrate to the ocean, returning as adults to spawn in the rivers. Salmonids are members of the trout familyÑand include all salmon and steelhead as well as all freshwater trout and chars. The other common anadromous salmonids on our north coast are the chinook or "king salmon" and the steelhead trout or "sea-run rainbow". Chinook are found in the bigger river systems such as the Klamath and Eel rivers, whereas steelhead are found in most all of our coastal streams, large and small.
Coho salmon spend one to two years in fresh water, followed by a year or more at sea, generally returning to fresh water to spawn near the end of their third year of life. Coho die after spawning and do not return to the sea as do some steelhead. Thus the myth that has been promoted lately that coho spend more of their time in the ocean than in fresh water (and thus we should look there to find the problems) is not based on fact. Coho spend up to half of their lifetime in freshwater, including the critical stages of juvenile development and the vulnerable period of returning upriver to spawn.
These fish have gone from relative abundance to "threatened" status in a relatively short period of time. In the past, coho were an important commercial fishery with as many as 3 million fish per year being caught in the ocean fishery of Oregon and California during the 1970s. With the decline of coho populations, commercial and recreational fishing for coho was prohibited in 1995, and it is now believed that there are less than 16,000 wild coho spawners in California and southern Oregon. (The number is from material published by the National Marine Fisheries Service; many fishery biologists believe the actual number is much lower). In Mendocino County, coho were once found in most all of the medium and large size streams, including the Eel, Ten Mile, Noyo, Big, Albion, Navarro, Garcia, Gualala, and Russian River. Although few data are available, spawning runs in these rivers are much smaller than in historic times.
The cause of coho decline is complex and multi-faceted and includes habitat degradation from logging, agriculture and road building as well as from dams, diversions and overfishing. These human activities have exacerbated the effect of natural environmental factors such as drought and poor oceanic conditions. In the coastal streams of Mendocino County (from the Gualala River north to the Mattole), logging and associated activity are probably the most important causes of coho decline. These activities put sediment in streams and raise stream temperatures which degrades the habitat for spawning and rearing. Such practices may also alter the timing and duration of river flows. In the Russian and Eel River drainagesÑwater diversion and agricultural practices are additional factors causing habitat deterioration.
Since 1993, the Mendocino Environmental Center, together with 21 other environmental groups, has been petitioning and suing the National Marine Fisheries Service (NMFS) to protect the fish under provisions of the Endangered Species Act. This agency, commonly called "nymphs" after its acronym NMFS, has jurisdiction (rather than the U.S. Fish and Wildlife Service), because coho are an ocean-going species. After a three year delay NMFS began the formal listing process. In October 1996 coho salmon in the Central Coast "Evolutionarily Significant Unit" (ESU) were listed as "threatened" under the Endangered Species Act and the "taking" of coho salmon was prohibited for these watersheds.
Each of these terms, "ESU", "threatened", and "take" has caused much confusion among the interested public trying to follow these activities. The Central Coast Evolutionarily Significant Unit (ESU) consists of all of the watersheds that originate along the coast south of the Mattole River. It thus includes almost all of the river systems in Mendocino County except the Eel, since the latter originates further north in Humboldt County near Ferndale, but has its headwaters in northern Mendocino County in the Willits and Covelo areas. An ESU is so named because the fish in such a region are generally more similar genetically than they are to other populations along the coast.
"Threatened" is one of two formal designations possible under the Federal Endangered Species Act. The act directs that a species be listed as "endangered" if they are "in danger of extinction throughout all or a significant portion of its range...". Similarly, the act requires that species be designated as "threatened" if they are "likely to become an endangered species within the foreseeable future...".
"Take" is a term from the Endangered Species Act which means "to harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect". This term was intended to include habitat destruction, and subsequent court rulings have upheld such an interpretation.
Then in May 1997, NMFS listed as threatened the coho from the Mattole River north to southern Oregon (The Southern Oregon/Northern California Coast Evolutionary Significant Unit better known as the "Transboundary ESU"). This was followed by a "no take" regulation for the California portion of this same ESU in July 1997.
The net result of all of this is that coho salmon are now listed as threatened and "take" of such fish is prohibited in all watersheds of Mendocino County. NMFS has not issued specific guidance on which activities they consider "take". However, in the July, 1997 Federal Register notice, NMFS listed general activities that they consider could "potentially harm, injure or kill" coho salmon. These include:
¡ "Land-use activities that adversely affect coho salmon habitat (e.g., logging, grazing, farming, road construction in riparian areas, and areas susceptible to mass wasting and surface erosion)";
¡ "discharges or dumping of toxic chemicals or other pollutants into waters or riparian areas;" and
¡ "pesticide applications".
Most importantly, NMFS has signalled that they do not consider California Forest Practice Rules as adequate to protect coho habitat from impacts of forestry operations on private lands.
NMFS will be developing final rules in the next few months for protection of coho and coho habitat. This is an important time for citizens to let NMFS know what sort of protection coho need in their watersheds. To date, two groups, Friends of Ten-Mile and Friends of Daugherty Creek and Big River have provided NMFS with draft guidelines for coho protection in their watersheds. Others are expected to do so in the next few months.
Copyright Mendocino Environmental Center 1997
Permission granted to excerpt or use this article if source is cited