Lecture 3.1 Manipulating Fishery Resources: Stream Habitat Management

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Lecture 3.1Manipulating Fishery
ResourcesStream Habitat Management

• Natural Resources 250
• Dr. Katherine Clancy
• Assistant Professor of Water Resources

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Outline

• Stream types.
• Habitat types.
• Protection strategies.
• Restoration strategies.
• Enhancement strategies.

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Stream Types

• Ephemeral streams flow only during precipitation
  events.
• Intermittent streams flow only during the wet
  season when water is present.
• Permanent streams flow all year.

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Habitat Considerations

• Water quality.
• Migration routes.
• Spawning grounds.
• Feeding areas.
• Cover from predators.

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Stream Management Protection Strategies

• Riverine wetlands.
• Channel form.
• Riparian vegetation.

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Protection Strategies ProblemsRiverine Wetlands

• Riverine wetlands are destroyed when channels are
  straightened.
• Riverine wetlands are degraded by urban and
  agricultural use.

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Farmland 25 football fields per day
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Forest 11 football fields per day
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Wetlands 8 football fields per day
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Impervious Area Increases Runoff
Increases the discharge to the stream.
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How do these changes show up in Channels
Hydrographs
Discharge (volume/time)
With wetland
Time
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Protection Strategies ProblemsChannel Form

• Channels are often straightened as part of
  floodplain management.
• Channels are often straightened by private
  landowners.

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Protection StrategiesProblemsRiparian Vegetation

• Riparian vegetation is often removed in
  agricultural areas.
• Riparian vegetation is often removed and paved in
  urban areas.

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Vegetation and Water Temperature
25ºC
23ºC
22ºC
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Flow Regimes
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Fish Calculator Habitat Suitability

• http//www.interwet.psu.edu/F1.htm

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Restoration Strategies

• Stabilize banks.
• Reestablish riparian vegetation.
• Remove dams.
• Regulate flows.

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Restoration StrategiesStabilize Banks

• Rip-rap can be used to deflect current away from
  eroded banks.
• Tree and brush revetments can provide cover for
  fish (over rip-rap).
• Planting vegetation on top of rip-rap prevents
  banks from slumping.

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Restoration StrategiesReestablish Riparian
Vegetation

• Riparian vegetation provides carbon for stream
  biota.
• Riparian vegetation provides cover for fish.

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Restoration StrategiesRemove Dams

• Remove dams that are not cost-effective.
• Re-licensing of dams requires justification.
• Biological impacts must be taken into account.
• Build fish-ways to facilitate fish migration.
• Fish-ways must be designed for each species.
• Often more costly than dam removal!

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Restoration StrategiesRegulate Flows

• Low flows result from particular uses.
• Irrigation withdrawals may dewater stream.
• Hydropower dams often fluctuate greatly.
• Minimum flows must be specified.
• Based on biological needs of fish species.
• Minimum flow associated with any limiting life
  history stage of the target species.

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Enhancement Strategies

• Fencing.
• Stabilize banks.
• Add woody debris.
• Bank covers current deflectors.

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Enhancement StrategiesFencing

• Cattle trample stream banks.
• Fencing excludes cattle.
• Grasses grow back quickly.
• Stream channel recovers original form.
• Rotational grazing will maintain grasses.

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Enhancement StrategiesStabilize Banks

• Rip-rap stabilizes severe damage.
• Brush stabilizes banks and provides cover.
• Brush bundles are placed on inside of bends.
• Brush mats are anchored to stream bottom.

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Enhancement StrategiesWoody Debris

• Woody debris provides cover for fish.
• Woody debris is often removed by humans.
• Add woody debris to provide cover for fish.
• Half-logs create overhead cover.
• Logs and boulders create deep scour holes.

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Enhancement StrategiesBank Covers

• Banks may not provide much cover.
• Engineer banks to provide cover.
• Trout populations increase when cover is limiting
  their abundance.
• Bank covers must match stream hydraulics.

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Enhancement StrategiesIntegrate Devices

• Multiple devices are better than one device.
• Bank covers favor adult trout.
• Brush bundles favor juvenile trout.
• Spawning substrate (gravel) may be limiting, but
  few devices mitigate this.

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