Management of Small Impoundments

Management of Small Impoundments

Chapters 21 (22)

Introduction

Pond = small impoundment <0.4 ha – 40 ha 0.2 ha – 2.4 ha (AFS Central States

Pond Management Work Group) Dam constructed to impound

water Various water sources

Springs, streams, precipitation, runoff

Introduction Usually privately owned Farm ponds

Livestock water Irrigation

Most numerous in central and southeast Important contribution to sportfishing Rarely regulated as a “water of the US”

Management Philosophy

Sustained or improved fishing quality

High catch rates and above-average sizes

Multiple Uses of Ponds Boating Fishing Livestock Bird hunting Swimming Aesthetics

Ecological Principles

Trophic Relationships Productivity and Biomass


Carrying capacity: max mass or density supported over a certain time period

K Density Fish Size


Average Fish Size varies as a function of overall pond productivity and population density


Influence of Aquatic Vegetation Increased primary productivity Decreased predator foraging

efficiency Decreased harvest efficiency Dense prey populations Stunted predator populations

Pond Types and Management Options

Warmwater Bass and bluegill, sometimes catfish Fall, winter, spring trout (summer kills) Most Common and Most research

Coldwater Trout, usually stocked

Coolwater Rare; Walleye, hybrid striped bass,

perch, etc.

All-Purpose Option Harvest of LMB, BG, and CC 30-38 cm (12-15 in) slot limit for LMB

after 4 years Reduces mid-size BG and allow some BG to

reach 8 in Harvest 75 LMB per ha (8-12 in) Harvest BG and CC at will Importance of LMB slot limit

Over harvest = Over population of BG Release slot fish and smaller = Over

population and stunting of LBM

Harvest Quota Option Due to problems with length limits Set harvest independent of length

Quota on number or weight per time Difficult:

Need accurate record keeping Tend to overharvest larger LMB and underharvest

small LMB Harvest BG and CC at will Harvest 3-10 times the amount of LMB C/R after quota is reached

Panfish Option Big panfish instead of LMB 15 in min length for LMB

Abundance of 8-15 in LMB reduce BG density

Large BG survive and grow > 8 in Small LMB generally

May compete with BG (remove some) Easy: unmanaged ponds tend to move

in this direction

Big BASS Option Reduce number of LMB 8-15 inches so

remaining individuals grow large Harvest 75 LMB 8-12 in and 13 LMB 12-

15 in per ha per year Release all LMB > 15 inches (except

bucket mouths) Stock gizzard shad as prey for large

LMB Catch rate is low but sizes are large Larger ponds Numerous small BG may reduce recruitment

of LMB

Catfish Only Option

In muddy or small ponds No structure for spawning or they

overpopulate and stunt Fathead minnow prey Unrestricted harvest Restocking to replace harvested

fish

Black Bass Only Option

Shallow, weedy ponds with too much cover (BG stunting)

Feed on crayfish, bugs, own young Need several year classes stocked

Prevents development of dominant year class

Inefficient use of pond resources?

Trout Options Coldwater ponds—spring fed Usually rainbow trout

Easy to control by stocking rates (won’t reproduce in standing water—brook trout will)

Must Restock Become accustomed to formulated fish foods

Fee-fishing ponds

“All Purpose” Recipe

Initial Pond Survey Population Status

Electrofishing and seining Assess population “balance”

Alkalinity Aquatic Weeds

“All Purpose” Recipe Kill the Pond Initial Stocking

Forage species (bluegill, shell crackers, fat head minnows)

Predator species (largemouth bass) Stocking Rates

Supplemental Stocking Essential in large ponds (>2 acres) Threadfin shad, golden shiners)


Liming Essential if pH < 7 and Alkalinity < 20

ppm Agricultural limestone Why useful?

“All Purpose” Recipe Fertilization

Can triple productivity Can cause unwanted algal blooms Once started, difficult to stop Granular, water soluble, liquid


Supplemental Feeding Dramatically increase size

and growth of BG and LMB. Only recommended if

Trophy Bass is the management objective.

Same negatives as fertilizer.


Aquatic Vegetation Control Optimum level at 20% in TX

reservoir Optimum level at 36% in IL pond

Aquatic Vegetation

Natural Succession of lentic systems Depressions accumulate material Increased organic matter and

nutrients Cultural Eutrophication Ponds become increasingly

susceptible to nuisance algae and vegetation

Aquatic Vegetation Control Mechanical:

Harvesting and Dredging Shading Draw Down

Aquatic Vegetation Control

Chemical: Herbicides Copper sulfate Nutrients stay Depletes DO Effective, quick,

cheap in small impoundments

Aquatic Vegetation Control Biological

Grass carp Non-native, illegal in some states Escape hatcheries and reproduce Triploid variety infertile Can completely eliminate vegetation, eat

invertebrates (crayfish) Nutrients stay (convert macrophytes to

phytoplankton) Barley Straw

May inhibit additional algal growth Mechanism uncertain: fungal chemicals? Nutrients stay


Aerators and Destratifiers Often necessary in fertilized ponds

or ponds that receive high nutrient runoff.

Avoid stratification and extremely low oxygen levels.

Expensive (especially with increasing gas prices)


Harvest Control Limit over harvest Maintain population “balance” Minimum length limits

Low recruitment situations Protects individuals until they reach maturity

Slot Limits High recruitment where minimum length limits

will lead to overpopulation and stunting Grows bigger fish Must harvest small fish

No harvestharvest harvest

12”8”trophy

Balance and Population Analysis Are stocked ponds really in balance?

Likelihood declines with ponds that are simple are artificial

Artificial ecosystems? Must manage hard to get what you want

Big aquarium? Ponds with a natural assemblage within a

natural habitat are more likely to be a self-sustainable ecosystem

Diversity of habitat Sustained source of water Prey diversity

Balanced Fish Populations

Characteristics Continual reproduction of predator

and prey Diversity of prey for all predators High growth rates Harvestable fish in proportion to pond

fertility

Balanced Fish Populations

Indices to assess balance Biomass Indices Length-Frequencies Indices Abundance-Weight Indices

Biomass Indices: F:C Ratio

Total weight of all forage fishes (F) / total weight of all carnivorous fishes (C) 3-6 = good 1.4-10 = balanced Low = too many carnivores High = too many forage fishes

Biomass Indices: Y:C ratio

Total weight of forage fishes small enough to be consumed by the average sized carnivore / Total weight of all carnivorous fishes (C) 1-3 = good 0.02-5 = balanced Low = too many carnivores High = too many forage fishes

Biomass Indices: AT value

Total availability value % that is “harvestable”

Total weight of harvestable fish / total weight of all fish

Need to define minimum weight harvestable 60-85% = good Low = stunted High = too many big carnivores

Length-Frequency Indices: Proportional stock Density (PSD)

# fish of a given species greater than or equal to quality length / # fish greater than or equal to stock length X 100 Quality Length – size most anglers like to

catch Stock Length – size at which fish reach sexual

maturity, minimum “recreational” length 40-70 balance for LMB 20-60 balance for BG

% of fish attractive to anglers

Length-Frequency Indices: Relative stock Density (RSD)

# fish of a given species greater than or equal to length you want / # fish greater than or equal to stock length X 100 Must ID the size you want Special case of PSD More sensitive to recognizing quality

of the stock

Comparing PSD and RSD Pop 1

PSD = 50 RSD-38 = 0

PSD = quality size/stock sizeRSE = other size/stock size

Pop 2 PSD = 50 RSD-38 = 15

PSD and RSD: Size Categories Base on percentage of world record

lengths Stock Length = 20-26% of the world

record length for the species (LMB 20 cm)

Quality Length = 36-41% (LMB 30 cm) Preferred Length (LMB 38 cm) Memorable Length (LMB 51 cm) Trophy Size = 80% (LMB 63 cm)

Table 21.1

Abundance and Weight Indices

Relative Weight (Wr) Measured weight (Wt) / predicted or

standard weight (Ws)

Length-Weight Relation W = aLb

Exponential relationship

W is a function of L to some power

a (constant) and b are parameters from L vs W relation

log W = log a + b log L

Equation for a line! Ws =standard weight

LMB Length-Weight relation

W = a L b

b = 3 Isometric growth

Growing in all directions in proportion Shape is not changing (rare)

b ≠ 3 Allometric growth

Growing faster in girth than length or vise versa; changing shape

More common growth Old fish grow more in girth than length

Wr = Wt / Ws

Do fish weight what they should < 85 = underweight and too

abundant 100 = in balance with food supply > 105 = too plump; pond can support

more fish

Standard Weight Equations

Largemouth Bass: Log10 Ws = -5.528 + 3.273 Log10 L

Bluegill: Log10 Ws = -5.374 + 3.316 Log10 L

Channel Catfish:Log10 Ws = -5.800 + 3.294 Log10 L

Internet Resources State Fish and Wildlife Agencies

http://www.tpwd.state.tx.us/fish/infish/ponds/ (TX) http://www.dgif.state.va.us/fishing/Pond_Manage

ment/index.html (VA)

Cooperative Extension Services http://www.wvdnr.gov/Fishing/FarmPondMgmt.sht

m (WV)

http://msucares.com/wildfish/fisheries/farmpond/management/ (MS)

http://www.aces.edu/pubs/docs/A/ANR-0577/ (AL) http://www.dnr.cornell.edu/ext/fish/pond1.htm

(NY)

Documents

Management of Small Impoundments