Historical analysis provides insight into key ecosystem processes and how they have changed. Because fish are adapted to conditions prior to significant human modification, knowledge of alterations can indicate root causes for declines in fisheries. This will tend to increase the effectiveness of restoration strategies. Although reference conditions in the Smith River basin are not precisely known, it is important to estimate ecosystem conditions that existed prior to extensive human interventions (Table 35). The estimate of historical conditions should not be confused with the goal of restoration which may or may not be similar (Williams 1995).
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Table 35. Assumptions concerning trends in habitat conditions in the Smith River system. Despite the uncertainty, these estimates are important in discerning ecosystem trends. |
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Habitat characteristics |
1850 |
1997 |
|
Surface area of estuary |
___? acres |
Greatly reduced |
|
Volume of estuary and tidal prism |
Large |
Small |
|
Pools on lower river >20 feet deep |
Many |
Few (none?) |
|
Grading of the lower river |
? |
Aggraded? |
|
Habitat complexity of lower river |
Very high? |
Low |
|
Spawning habitat on the lower river |
Abundant? |
Abundant? |
|
Habitat complexity of upper watershed |
? |
? |
|
Spawning habitat in the upper watershed |
? |
? |
|
Woody debris on entire stream network |
High? |
Low? Medium? |
|
Sediment loads |
Very low? |
Low |
|
Connectivity throughout the stream system |
High? Medium? |
Low? Medium? |
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Connectivity from the estuary to Rowdy Creek |
High? |
Low? Medium? |
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