The Salmon Decline Continued

The Salmon Population

Factors Causing Salmon Decline:

Salmon Decline Matrix

Problem Dams Logging Changing
Climate
Agriculture Pop. Growth Over Fishing Other
Salmon Migration Barriers Big Timenononononono
Barriers to Reaching Spawing Grounds Yes noYesnonoYes!no
Reduced Number of Young Salmon reaching seayes yesnonononobird
predation
Pesticide Exposureno YesnoYesnonono
Industrial Pollutants Exposureno nononoYesnono
Loss of Streamside Vegetation and Functionsno YesnoYesYesnono
Increased Sediment Loadno YesYesYesYesnono
Natural Habitat Destructionyes yesnoyesyesnono
Reduced Fresh Water Flow in Rivers and Streams yes nonoyesyesnono
Abnormal water temperaturesyes noyesyesnonono
Reduced upwelling and nutrient/food supplyno noyesnononocompetition with hatchery fish
Estuary Degradation no YesnonoYesnono
Loss of cool deep pools in streamsno Yesnonononono

Qualitative Scorecard:


Abstract of a Recent Technical Paper

Evidence of a Nutrient Deficit in the Freshwater Systems of the Pacific Northwest. A comparison of historic and current levels of salmon abundance was used to determine the current deficit of marine-derived nutrients for Pacific Northwest streams. This nutrient deficit may be one indication of ecosystem failure that has contributed to the downward spiral of salmonid abundance, further diminishign the possibility of salmon population recovery to self-sustaining levels.

This is the raw salmon count data at Boneville Dam that we will inspect more closely below. Evidence of quasi-cylical behavior is apparent. Generating count Data (last year and this year are high!)

Some relevant WWW resources:


White Men Luv Fish


Pacific Northwest Index


Canadian Harvest Increases

Some Salmon Links

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.


World Salmon Harvest

What about the viability of Dam Breaching?

the poll on tuesday showed that most believed this would *not* be effective. However, many thought it would or didn't know.

Pros and Cons of Dam Breaching:

Arguments For:

  • restore Salmon runs
  • restore river to its more natural state
  • create short term jobs (sledgehammer crew).

Arguments Against:

  • Loss of Power
  • Loss of flood control
  • Loss of Irrigation
  • Loss of River Navigation
  • Increased Turbidity
  • Toxic Waste movement down the river

How we can gather objective data on each of the items in the list.?

First we noticed that the listed items under Aguments against are quite obvious and really don't require justification. All of these things would happen, it just matters to which degree they would happen and this is very difficult to model.

So let's concentrate on the other items in the Arguments For column.

The principle hypothesis here is whether or not dams have caused a "catastrophic" loss of population.

We can use salmon count data as a means of establishing a baseline. We can then convolve that data with the following simple model:


X ----------|-------------|--------|------|--------|----|---|--|->  X'

            1             2        3      4        5    6   7  8

Suppose we have a system where X salmon enter and have to pass 8 dams to reach X'.

The issues are:

These hypothesis can be tested to some extent by the actual salmon count data which exists at each dam. That data is readily available .

But we aren't doing an indepth analysis here. Let's keep it simple.

Under the model where all dams are equal then we should see something like this in the data.

X1 < X2 < X3 < X4 < X5 < ...

While there are complicating factors, this basic pattern should be defined the data on upstream salmon counts. You will be testing that in your next homework assignment.

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