Geoscience Reference
In-Depth Information
Although salmon populations have l uctuated over time as part of natu-
ral cycles, their numbers have reached an all-time low over the past several
decades. Fisheries biologist Jim Lichatowich writes in his topic
Salmon
without Rivers:
h e salmon are among the oldest natives of the Pacii c Northwest, and over
millions of years they learned to inhabit and use nearly all the region's fresh-
water, estuarine, and marine habitats. Chinook salmon, for example, thrive
in streams l owing through rain forests as well as through deserts; they
spawn in tributaries just a few miles from the sea and in Rocky Mountain
streams 900 miles from saltwater. From a mountaintop where an eagle
carries a salmon carcass to feed its young, out to the distant oceanic waters of
the California current and the Alaskan Gyre, the salmon have penetrated the
Northwest to an extent unmatched by any other animal. h ey are like silver
threads woven deep into the fabric of the Northwest ecosystem. h e decline
of salmon to the brink of extinction is a clear sign of serious problems. h e
beautiful ecological tapestr y that northwesterners call home is unraveling; its
silver threads are frayed and broken. (p. 6)
In many ways, the salmon in Pacii c coastal rivers rel ect the health of the
entire watershed: their decline is a warning sign that these ecosystems are suf-
fering. h e chinook salmon experienced unprecedented declines from 2006
to 2011, when their numbers dropped so low that the entire salmon i shery
from the northern Oregon border to Mexico was closed in 2008 and 2009
and was severely restricted in 2010.
h e coping strategies developed by salmon, dubbed the “portfolio ef ect,”
have allowed salmon from California to Alaska to survive for millions of
years. Salmon hatcheries may produce more juveniles, but they have been
unable to overcome the obstacles and habitat destruction that has accompa-
nied water development in the West.
California's Central Valley: Disappearing Wetlands and Lakes
Another poignant example of the environmental price of water develop-
ment is the disappearance of enormous expanses of wetlands in California's
Central Valley, including three enormous lakes that were located in the
southern end of central California. A century ago, California's vast Central
Valley would change seasonally as precipitation and river l ows changed. h is
expanse of grassland dotted with oak trees in the dry summer season would
be transformed into lush wetlands and marshes during the wet winter season
