Stream and River
Management
•
Lecture
Outline
–
Conceptual framework for
streams and rivers
–
Managing large rivers
•
Assignments
–
Paper discussion
(Churchill et al., 2002)
–
Exam 2 on Monday!
Large Rivers
1)
Defined
in book as 6th order or greater
Spatial and
Temporal Hierarchy of Rivers and Streams
River Continuum
Concept
1)
Emphasizes
longitudinal structuring of rivers
2)
Predicts
highest diversity occurs in medium-sized rivers
Flood-Pulse
Concept
1)
Emphasizes
lateral interactions between river and floodplain
2)
Predicts
highest diversity occurs in large rivers
Serial
Discontinuity Concept
1)
Transforms
lotic to lentic habitat
a) Favor centrarchids
b) Detrimental to riverine fishes (cyprinids, sturgeons,
paddlefish)
2)
Channel
deepening below dam
a) Reduces off-channel habitats (e.g., secondary
channels)
3)
Enhanced
sediment deposition
a) Because of reduced hydraulic gradient and velocities
Lock and Dams
Wing Dikes
1)
“Focus”
flow to navigation channel
2)
Reduce
off-channel habitat
3)
Provide
habitat for catfishes, walleye, crappie, bluegill and largemouth bass
4)
Notched
dikes can enhance fish habitat
Navigation Traffic
1)
Creates
wake
2)
Increases
turbidity and erosion
3)
Rapid
fluctuation in water level
4)
Stranding
potential of young fishes subjected to vessel-induced drawdown
a)
Shovelnose
sturgeon – 67%
b)
Paddlefish
– 38%
c)
Bigmouth
buffalo – 2%
d)
Bluegill
– 20%
Tailwater
Fisheries
1)
Cool
water in warm climate
a) Hypolimnetic release
2)
Highly
productive
a) Soluble nutrients released with anoxic water
3)
Problems
a) Gas bubble disease
b) Heavy metals and sulfer
Commercial
Fisheries
1)
Untapped
resource
2)
Common
carp, goldeye, catfishes, buffalos and freshwater drum
3)
Benthic
fishes
4)
Toxins
can be a problem
5)
Long-lived
species vulnerable to overharvest
a)
Mussels,
sturgeon, alligator gar?
Sampling Large
Rivers
1)
Multiple-gear
approach
2)
Small
fishes inshore
a) seining
3)
Large
fishes inshore
a) electrofishing
4)
Offshore
fishes
a) Trawling
b) Hoop nets
c) Drift gill nets
5)
Off-channel
habitats (e.g., backwaters)
a) Trammel nets
b) Gill nets