The Salmon Decline

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The Decline of the Northwest Salmon?

The apparent decline of the salmon in the Columbia river system is one of the most complex environmental problems we have.

However, 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.

The answer to the quiz question indicates the majority of this class believes this root cause

We wish to access of this simplification is valid by examining some of the broader issues and looking at the actual data which is available.

The Salmon controversy is an excellent example of arguments made largely on belief, instead of knowledge that is supported by the actual data.

As the dams are obvious targets of opportunity this belief system can be supported. But can it really be supported by the data? .

It is also an excellent example/reflection of another problem that effectively prohibits meaningful discourse; reactive vs proactive positions

Let's look at some data. Most of this data comes from fish counts done at Bonneville Dam starting in 1938 (again the next homework assignment will have you make use of this data):

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/ag) or global (e.g. Global Warming)

Graph shows harvesting by Tribal communities with protected fishing rights. Some degree of "over harvesting" is apparent.

Graph shows total salmon catch off the coast of North America (including Alaska).

Decline of In-River catches which is frequently used as the "best" indicator for overall salmon decline in the Columbia River System:

Implication is that increases in ocean catch are directly responsible for decreases of in-river catches also shown.

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