with outside fish, these three streams
hold a strong in the future health of the species.back to oceanography home page
| Other Student Pages on Salmon |
COHO SALMON IN WEST MARIN
The coho salmon in West Marin have and continue to face many obstacles
in their fight to survive. Today there is a lot of interest and effort going
into saving the small portion of the population that still survives. The
coho of West Marin are still found in the Olema, Redwood and Lagunitas creeks.
Up till thirty years ago salmon could also be found in Pine Gulch Creek.
The three streams that continue to carry fish hold an estimated 10% of the
remaining coho in California. While Redwood Creek is the only one that has
never been planted with outside fish, these three streams
hold a strong in the future health of the species.
In the past century and a half the watersheds of these creeks have been heavily logged While the last logging in West Marin ended about thirty years ago, ranching and farming continue along many parts of the streams. None of these practices are inherently evil, but in order for the larger community to survive there must be some thought and care put into how the practices are carried out.
Along portions of the creeks that are open to cattle simply fencing along either side of stream so that the cattle are kept off the banks would and has had a tremendous effect. When done correctly and not half ass and followed by the planting of some willow shoots along the banks a healthy community of riparian vegetation can easily be built. Where this has been done along the Olema Creek system the effect is clearly visible. With the recent listing of the coho as endangered there is hope that the National Park will have the power and guts to push through the fencing off of the rest of the problem areas along Olema creek.
This summer the young coho in the Olema Creek are also dying off because
of the dry spring we've had. The strong rains in December allowed many returning
breeders to swim way up into small tributaries of the Olema Creek. Since
then the eggs have hatched, but there has been no new rain. Walking along
some stretches of creek one can see hundreds of coho trapped in small, ever
shrinking pools. There have been some small efforts made to net the land
locked fish and move them into the main stream bed, but these have been
slow because of the regulations that go along with their status as endangered.
This brings up some of the flaws in the Endangered Species Act.There are many well intentioned people working diligently on the local level to save the coho. When the coho became listed as endangered new rules were attached to how those people could handle and work with the fish. The basic rule is hands off. Small backyard hatcheries on the Mattole River that know what they are doing have had to bend the rules to keep running. A few retired locals in West Marin have been told not to try to move the coho out of the drying pools along the Olema Creek because of the fishs' new status. The Small attempts to net the fish were made with the supervision of the park and took a week of talking to get done.
The coho in Pine Gulch Creek were probably killed off in the early 1970s when a large local farm began damming up the creek in the early spring and through the summer to hold back water for irrigation . The dams were put in each year before the young smolt of the year could make their way out to sea, thus keeping them in the fresh water for too long a period of time.
Today there is a lot of effort going into determining the genetic makeup of the coho of West Marin. The U. C. Bodega Marine Laboratory has started using "nuclear" DNA analysis on tissue samples taken from coho carcasses in Olema, Lagunitas and Redwood Creeks to study the population structure of the fish in these streams. The plan is to see if there are Evolutionary Significant Units of salmon in the creeks that can be used in future coho management on the west coast. This DNA analysis should be able to determine how site faithful coho returning to the streams to breed are. The study might also determine if there are fish from west Marin that struggle into other river systems, like the Russian River, and provide genetic contributions to those populations. If this is found to be true then the coho from West Marin could be used to help rebuild the Russian River population without the danger of weakening the population with fish that are not adapted to that stream system.