Biology Reference
In-Depth Information
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Ta rget CVPIA (B2)
Actual CVPIA (B2)
Ta rget EWA purchases
Actual EWA purchases
Ta rget EWA operational assets
Actual EWA operational assets
Figure 14. Gap between target (set by CALFED and CVPIA) and actual (measured or
released) amounts of water dedicated for environmental uses, 2000-2005. EWA
refers to environmental water account; CVPIA to the Central Valley Water Project
Improvement Act. (Environmental Defense Fund)
Hatcheries?
Any attempt to restore native populations of Sacramento and San Joaquin
River Salmon must consider that the few remaining fish aren't so native
anymore. This issue came to a head in 2005, when poor ocean conditions
killed nearly all of the juvenile fall Chinook that reached the sea.
Peter Moyle of UC Davis puts the problem squarely at the doorstep of
the hatchery system: “These fish have been having hard times in recent
years because of their uniformity in life history and genetics. Those that
make it to the ocean tend to be the same size and to do the same things
because of their hatchery parentage, so if conditions are bad, most die.
Under natural conditions, the wild salmon in each stream would have dif-
fered from salmon in other streams, and had more variability in size and
time of ocean entry. This allowed large numbers of fish to avoid unfavor-
able conditions. With hatcheries, we have taken away this resilience.”
The traits needed to thrive in a hatchery are very different from those
required to survive in the wild. “If a fish is trying to defend its territory in
a trough with 50,000 other fish, it's wasting its time. But in the wild, that's
the path to success,” says the U.S. Environmental Protection Agency's
Bruce Herbold. Studies show that selection for hatchery traits can occur
among Steelhead within just two generations. Even if both of the parent
fish used to sire new hatchery fish were born and raised in the wild, their
