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: http://zebu.uoregon.edu/1998/ph162/l13.html
Дата изменения: Tue May 12 03:36:57 1998 Дата индексирования: Tue Oct 2 00:30:09 2012 Кодировка: Поисковые слова: легирование |
The apparent decline of the salmon in the Columbia river system is one of the most complex environmental problems we have. However, it is often simplified down to a battle of
VS
Innocent Fish
In other words, this problem has been over-simplified by the media and others to one single root cause, namely the construction of hydroelectric dams on the Columbia river system. Today we assess if this simplification is valid and address the issue of where we are going to find the replacement 15,000 MW of power if/when the dams go away.
The Salmon controversy is an excellent example of arguments made largely on belief, instead of knowledge that is supported by the actual data .
JAVA Applet Alert: Run the SalmonVille Simulation
Factors Causing Salmon Decline:
Let's first look at some data:
|
Decline of In-River catches This frequently used as the "best" indicator for overall salmon decline in the Columbia River System |
This is the raw salmon count
data at
Bonneville Dam. Evidence
of quasi-cylical behavior is apparent. not historically unprecedented. |
Graph shows total salmon catch off the coast of North America (including Alaska).Implication is that increases in ocean catch are directly responsible for decreases of in-river catches |
Fish Counts at Bonneville:Blue line represents growth of non-harvested fish in the Columbia River system. The implication is that competition for food/nutrients is increasing rapidly. |
Its getting warmer earlier in the season with time in the Columbia river. Is this cause local (e.g. dams/agriculture) or global (e.g. Global Warming) |
Graph shows harvesting by Tribal communities with protected fishing rights. Some degree of "over harvesting" is apparent. |
Some relevant WWW resources for the above:
White Men Luv Fish
The above documents and data strongly suggest that a significant
reason for Columbia river salmon decline is due to increased harvests in
Alaska and Canada.
This is likely a reflection of where the Salmon are and this is strongly
coupled to decadel climate changes in the Alaska-BC-PNW region.
This implies, that at any particular point in this region, over
timescales of 50 years, salmon counts/catches will be cyclical
in nature.
More Factors:
Power to replace Salmon Killers
What are the options to finding 15,000 MW of power, continuously
delivered, at 4-5 centers per KWH?:
Its capacity of 1340 MW is vital to the PNW and hence large State funds
have now been allocated for pollution reduction. Consumer ultimately
pays for this.
Is there really an acceptable alternative?
The Centralia Steam Plant is the
single largest producer of sulfur dioxide in the state (WA)
and is the second dirtiest producer of electricity west of
the Mississippi.