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Chapter 6 -- Changes and Trends in Stream Habitat and Fisheries

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). When we estimate the historical conditions, we should not assume that these conditions are the goal of restoration (Williams 1995). For example, although there is a little or no evidence that the Smith River estuary contained large quantities of large woody debris at the onset of European/American settlement, we should not therefore assume that the estuary is "not supposed to" have large woody debris.

 

Table 35. Assumptions concerning trends in habitat conditions in the Smith River system. Despite the uncertainty, these estimates are important in discerning ecosystem trends.

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?

Connectivity from the estuary to Rowdy Creek

High?

Low? Medium?

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