Habitat Management in Reservoirs

• Lecture Outline

– Why?

– How?

• Water levels

• Structures

• Vegetation

– Kansas example

• Assignments

pp. 249-284 (IFM)

Why Manage Habitats?

1) GROWTH, SURVIVAL, and RECRUITMENT

a) Increase habitats available

b) Spawning

c) Protection

d) Ambush

e) Enhance food base / concentrate food

f) Water quality

g) Nutrient cycling

Management Options

Water Level Management

1) Flood terrestrial vegetation

2) Nutrients

3) Habitat

4) Food items

5) Concentrate predator and prey

Management Options

Water Level Management

“Drawbacks of drawdowns”

Other

1) Most reservoirs fish not a major concern

2) Stochastic weather patterns

Management Options

Artificial and Natural Structures

1) Provide cover for some life stage of fish

2) Provide substrate for “slime” or epiphyton

3) Provide cover for fish food

4) Habitat Enhancement Structures

a) Brush piles

b) Tires

c) Stake beds

d) Standing timber

e) Rock and gravel reefs

f) Aquatic macrophytes (a.k.a. plants)

i) + Provide excellent spawning and nursery habitat

ii) + Cover from predation

iii) + Ambush sites

iv) + Epiphyton

v) + Littoral zooplankton

vi) + Macroinvertebrates

g) Aquatic macrophytes (a.k.a. plants)

i) + Bank stabilization and reduces erosion

ii) + Increase water clarity: reduced turbidity and shading phytoplankton

iii) + Decrease water temperatures

iv) + Increase DO

v) + Nutrient cycling

5) Aquatic macrophytes (a.k.a. plants)

i) Some intensive effort may be involved

ii) Possibility of exotic species introduction

iii) Densities too high inhibit fish from feeding

iv) Reduce DO if overabundance of submergents

v) Alters food webs

Example In Kansas

Background

1) After trophic depression

2) KDWP

3) Water level fluctuations?

4) Artificial structures

5) Macrophytes

a) Abundant macrophyte habitat

b) Fit management goals

6) So plant them!

a) Harsh environmental conditions for seedlings

b) High abundance of carp

c) Root up most macrophytes

7) Water willow Justica americana

a) Emergent species

b) Carp resistant

Example In Kansas

Study

1) Water willow

2) Reservoirs

Example In Kansas

Study Parameters

1) Largemouth bass and sunfish density

a) Daily growth, diet analysis, and condition (lipid analysis

2) Fish assemblage dynamics

3) Zooplankton and macroinvertebrate densities

4) Physiochemical variables

a) DO, turbidity, conductivity, temperature

b) Substrate, depth, slope

5) Stem densities and woody debris

Sampling

Results