• TABLE OF CONTENTS
HIDE
 Copyright
 Front Cover
 Introduction
 Description of grass carp
 Management techniques
 Permit requirements for grass...
 Summary
 Additional readings
 Acknowledgement
 Back Cover






Group Title: Bulletin - Agricultural Experiment Stations, University of Florida - 867
Title: Grass carp
CITATION PAGE IMAGE ZOOMABLE PAGE TEXT
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00027493/00001
 Material Information
Title: Grass carp a fish for biological management of hydrilla and other aquatic weeds in Florida
Series Title: Bulletin Agricultural Experiment Stations, University of Florida
Physical Description: 10 p. : col. ill. ; 23 cm.
Language: English
Creator: Sutton, David L ( David Lee ), 1939-
Vandiver, Vernon V ( Vernon Victor ), 1944-
Publisher: Agricultural Experiment Stations, Institute of Food and Agricultural Sciences, University of Florida
Place of Publication: Gainesville Fla
Publication Date: 1986
 Subjects
Subject: Ctenopharyngodon idella   ( lcsh )
Aquatic weeds -- Biological control -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Bibliography: p. 10.
Statement of Responsibility: David L. Sutton and Vernon V. Vandiver, Jr.
General Note: Cover title.
General Note: "December 1986."
Funding: Bulletin (University of Florida. Agricultural Experiment Station) ;
 Record Information
Bibliographic ID: UF00027493
Volume ID: VID00001
Source Institution: Marston Science Library, George A. Smathers Libraries, University of Florida
Holding Location: Florida Agricultural Experiment Station, Florida Cooperative Extension Service, Florida Department of Agriculture and Consumer Services, and the Engineering and Industrial Experiment Station; Institute for Food and Agricultural Services (IFAS), University of Florida
Rights Management: All rights reserved, Board of Trustees of the University of Florida
Resource Identifier: aleph - 000898564
oclc - 15547656
notis - AEK7269
issn - 0096-607X ;

Table of Contents
    Copyright
        Copyright
    Front Cover
        Front Cover
    Introduction
        Page 1
    Description of grass carp
        Page 2
        Page 3
    Management techniques
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
    Permit requirements for grass carp
        Page 10
    Summary
        Page 10
    Additional readings
        Page 10
    Acknowledgement
        Page 10
    Back Cover
        Page 11
Full Text





HISTORIC NOTE


The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
(EDIS)

site maintained by the Florida
Cooperative Extension Service.






Copyright 2005, Board of Trustees, University
of Florida





6DTcember1986


GRASS CARP

A Fish for Biological
Management of Hydrilla and Other


Aquatic Weeds in


Florida


itton ancVernon V. Vandiver, Jr.
5 981
* wl f9cult Experiment Stations
od and Agricultural Sciences
University of Florida, Gainesville
J. M. Davidson, Dean for Research


Bulletin 867








Grass Carp

A Fish for Biological
Management of Hydrilla and Other
Aquatic Weeds in Florida


David L. Sutton and Vernon V. Vandiver, Jr.


Dr. David L. Sutton is Professor (Aquatic Weeds) and Dr. Vernon V. Vandiver
is Associate Professor (Aquatic Weeds Specialist) at the Fort Lauderdale
Research and Education Center, Fort Lauderdale.


Introduction
Abundant growth of aquatic plants causes serious problems in ponds,
lakes, rivers, and irrigation and drainage throughout Florida. In some
situations, native aquatic plants become weeds, but most often exotic
plants introduced from areas outside the state flourish under the
favorable growing conditions found in Florida. Long-term economical
solutions to Florida's aquatic weed problems have been elusive and
there is a need for control techniques to alleviate aquatic weed
problems.
This bulletin provides information on a biological method, the grass
carp (Ctenopharyngodon idella Val.), for management of some of
Florida's aquatic weed problems. Emphasis is placed on use of this fish
to control hydrilla (Hydrilla verticillata [L.f.] Royle) and other
submersed aquatic plants.
Since the grass carp is a living organism in contrast to either
herbicides or mechanical devices used for aquatic weed management -
a somewhat different approach is required. A knowledge of the life
cycles of plants that become weeds and feeding behavior of the fish are
important considerations in understanding the various ways in which
grass carp can be used to manage plant problems. The grass carp will
not be useful for all aquatic plant problems; rather it offers the poten-
tial to effectively and economically manage certain of them.
Man has probably been the single most important factor in the
spread of hydrilla (Figure 1) and other aquatic plants. The demand for
aquatic plants used in aquariums and elsewhere has resulted in their
sale and distribution throughout the country.







Also, once established in natural waters, the plants may be spread by
boaters traveling from one body of water to another. It is to be hoped
that public recognition of problems some of these plants may cause will
lead to regulations and public cooperation to cease their introduction
and transportation, purposeful or inadvertent.
Herbicides are frequently used for hydrilla control, but biological
organisms offer unique advantages for management of hydrilla and
other aquatic weeds. Advantages of using effective, safe organisms to
manage aquatic weeds biologically include (1) longevity of the method
once it has become established; (2) constant feeding activity against the
growing weed; (3) low long-term costs; (4) high effectiveness on some
plants; and (5) in the case of fish, the potential for conversion of the
weed to a useful protein product (fish flesh).
The most promising biological agent for many submersed plant
problems and some other aquatic weeds is the grass carp (Figure 2),
also commonly called the white amur.

Description of Grass Carp
This fish is indigenous to those rivers in the eastern part of the Union
of Soviet Socialist Republics (USSR) and China that flow into the
Pacific Ocean between latitudes 50 North and 23 North.
The grass carp has been introduced into more than 50 countries
throughout the world for aquatic weed control and aquaculture. In
some countries, the grass carp is an integral part of fish culture and
forms an important source of protein for human consumption.
The grass carp was considered for introduction into the U.S. primar-
ily because of its plant eating diet, which was thought to have great
potential for the control of aquatic weeds. In 1963 the U.S. Bureau of
Sport Fisheries and Wildlife Fish Farming Experiment Station,
Stuttgart, Arkansas, in cooperation with Auburn University,
imported grass carp for experimental purposes; in 1970, this fish was
introduced into Florida primarily for researchers to study its ability to
control hydrilla.
Wide-scale use of the grass carp in Florida and many other states
during 1970 to 1984 was limited and closely regulated due to fears
about its reproduction and negative impact on sport fish. Since the
grass carp's potential for causing such problems was evident, early
research focused on developing a fish that would be non-reproductive
but would retain the grass carp's herbivorous diet.
The natural grass carp is diploid with a chromosome number (2N) of
48. During the past few years, research with the grass carp has
resulted in the production of a sterile triploid grass carp (3N), which
has an extra set of chromosomes. The aquatic weed control capabilities
of the triploid fish are essentially the same as the diploid.






























Figure 1: Hydrilla may completely dominate a body of water excluding
growth of native species and interfering with water uses such as
the irrigation pump system shown here.


Figure 2: A large grass carp grown primarily on hydrilla.







The triploid grass carp is produced in the same way as the diploid,
except that fertilized eggs subjected to heat, cold, or pressure shock
result in the formation of fish with an extra set of chromosomes for a
total of 72. The extra chromosomes make these fish sterile.
The nuclei of cells of the triploid grass carp are larger than those of
diploid fish. An instrument such as the Coulter Counter can be used to
measure the diameter of the nuclei of fish blood cells. Therefore, it is
possible to screen fish considered for introduction into aquatic weed
problem areas to assure that each fish stocked is a triploid.
The grass carp tolerates cold water and also flourishes and grows at
rapid rates in warm waters such as those found in Florida. These
herbivorous fish may grow at a rate of 2 pounds (0.91 kg) or more per
month when sufficient vegetation is available. The young fish grow at
a much faster rate than older, mature fish, and females grow faster
than males. In Florida, some fish have grown to 40 pounds (18 kg) with
an apparent life span of approximately 10 years.
The grass carp is primarily a grazerr"; it tends to feed on the surface
and in shallow water. At times it can be seen feeding with its back and
tail extending above the surface.
The grass carp prefers submersed plants and the soft tips of young
tender plants (Table 1). Small grass carp prefer musk-grass over
hydrilla when both plants are present, but large fish will consume
hydrilla before musk grass. Even though young fish will feed on
various species of Cladophora and Spirogyra and other filamentous
algae, the grass carp is not normally considered an effective method to
control many types of algae. Feeding rates of large, mature fish on
algae are not well known.
When the preferred food of the grass carp is not available, this fish
feeds on terrestrial vegetation hanging over the surface of the water. In
fact, the name "grass carp" comes from its unique ability to consume
terrestrial grasses. Other terrestrial plants eaten by the grass carp
range from banana leaves (Musa spp.) to various dried grasses,
including clippings from golf courses or similar turf areas. Caution
should be exercised when feeding grass clippings to grass carp. Some
pesticides commonly used on turf areas are quite toxic to fish.
The ability of grass carp to consume and utilize aquatic plants
depends on the size of both plants and fish. Additional factors which
influence the feeding behavior of grass carp include their size, age,
gender, and population density, and the species, abundance, and loca-
tion of plants within a body of water.

Management Techniques
Birds, snakes, and other fish prey on small grass carp. Based on
measurements of mouth width and total length for largemouth bass







Table 1. A few common Florida aquatic plants eaten by grass carp in
the approximate order of preference.

Order of Common Scientific
preference name name

1 Hydrilla Hydrilla verticillata [L.f] Royle
2 Musk-grass Chara spp.
3 Southern maiad Najas quadalupensis (Spreng,)
Magnus
4 Brazilian clodea Egeria densa Planch.
5 Water-meal Wolffia spp.
6 Duckweeds Lemna spp. and Spirodela spp.
7 Azolla or water-fern Azolla caroliniana Willd.
8 Pondweeds Potamogetan spp.
9 Coontail Ceratophyllum demersum L.
10 Torpedograss Panicum repens L.
11 Cat-tail Typha spp.
12 Water-aloe Stratiotes aloides L.
13 Watercress Nasturtium officinale R. Br.
14 Eurasian watermilfoil Myriophyllum spicatum L.
15 Tapegrass or eel-grass Vallisneria americana Michx.
16 Parrott-feather Myriophyllum aquaticum (Vell.)
Verdc.
17 Water hyacinth Eichhornia crassipes (Mart.) Solms
18 Water-lettuce Pistia stratiotes L.
19 Water-lillies Nymphaea spp.
20 Spatterdock Nuphar luteum (L.) Sibth. & Sm.

(Micropterus salmoides Lacepede), it has been calculated that grass
carp must be greater than 18 inches (450 mm) in length to eliminate
predation. Therefore, when predators are present, fish to be stocked
should be at least 12 inches (0.3 m) in length or 1 pound (0.45 kg) in
weight for good survival. Mortality rates increase sharply with smaller
fish.
Small grass carp have a better chance of survival if they are stocked
when the weeds are dense enough to provide protective cover. When
the weed biomass is low, such as after a herbicide treatment, use of
mechanical methods, or in a new body of water, fish in good condition
and weighing 5 pounds (2.3 kg) or more will survive better than
smaller fish.
To remove hydrilla and other aquatic weeds with grass carp alone,
fish must be stocked in sufficient numbers so that their consumption
rate exceeds the growth rate of the plants. With so many factors
influencing the feeding rate of the grass carp and the growth rate of the
plants, it is impossible to give one specific stocking rate that will apply
for every situation.
Rates of 20 to 255 grass carp per acre (50 to 638 fish per hectare) have
been found to provide effective control of hydrilla.






























Figure 3: A. Hydrilla growth prior to stocking of grass carp.


B. The same pond after the hydrilla was controlled with these
herbivorous fish.



































Figure 4: A. An agricultural waterway filled with hydrilla
B. A similar waterway after control of hydrilla with herbicides
and grass carp.


Figure 5: A barrier of evenly spaced PVC pipe to prevent escape of grass
carp in an agricultural area's irrigation ditch.







Removal of hydrilla with 40 fish per acre (100 per ha) is shown in
Figure 3. A dense growth of any weed will obviously require more fish
than a sparse amount of the plant. One approach is to stock 20 to 30 fish
per acre (50 to 75 grass carp per hectare). Then in a year to a year and a
half, add more fish if the desired level of control has not been achieved.
In a body of water, the area infested with weeds in relation to the
total area may be taken into consideration when determining the
number offish to stock. Transect lines, a recording fathometer, biomass
sampler, or aerial surveys can be used to help estimate the amount of
weeds present. In this way, the fish can be stocked according to the
amount of vegetation, rather than the total area of the body of water
under consideration.
Very low oxygen levels can be encountered during the early morning
or on cloudy days in bodies of water containing dense weed growth. In
this case, it is better to use herbicides or to mechanically remove the
hydrilla before stocking the fish, or better yet, wait for cooler water
temperatures before stocking. A few measurements of dissolved
oxygen made just prior to sunrise, particularly during the summer,
will give a good indication of whether sufficient dissolved oxygen is
present for good fish survival. Dissolved oxygen readings of at least 3
ppm will help ensure good survival of the fish. It should also be noted
that dissolved oxygen levels tend to decrease with increasing water
temperature.
Use of herbicides to remove a majority of the biomass of hydrilla
before stocking with grass carp will reduce the number offish required,
since the fish need to consume only the newly emerging hydrilla
growth. This integrated approach appears to be an efficient and cost-
effective way to manage hydrilla.
When herbicides are used, sufficient time must be allowed for the
indirect effects of the herbicide to diminish prior to stocking grass carp.
Although most aquatic herbicides are not toxic to fish, the decaying
vegetation may reduce dissolved oxygen to levels unsuitable for good
survival of fish. Oxygen measurements should be taken to indicate
whether the water is suitable for stocking grass carp.
In small bodies of water, 5 fish per acre (13 grass carp per hectare)
have controlled hydrilla regrowth following use of herbicides. Rates
lower than this may be possible since 5 fish per acre in some situations
will eliminate all submersed plant growth. Therefore, to prevent
regrowth of hydrilla but at the same time allow for growth of other
desirable plants, rates of 1 to 3 fish per acre (3 to 8 fish per hectare) may
be suitable, with an occasional spot treatment of herbicide to control
any new growth of hydrilla which becomes more abundant than the
fish can consume.







One area of interest is the use of grass carp to manage hydrilla
concomitant with establishment of desirable, native aquatic plants. In
order to accomplish this, low numbers offish or the use of plants low on
the list of foods preferred by the fish are important considerations.
With grass carp it may be possible to eliminate hydrilla in many bodies
of water and promote growth of desirable aquatic plants to enhance
water quality.
The grass carp has also provided control of hydrilla in some flowing
water situations. Figure 4 shows an agricultural canal before and after
use of herbicides and stocking of grass carp.
Limited work has been done on the use of grass carp in conjunction
with mechanical control methods prior to fish stocking. However, it is
likely that the number of fish required following mechanical removal
of hydrilla would be higher than the number required after application
of herbicides, but considerably lower than the number required if fish
alone were used.
Stocking of grass carp must take place after any negative effects of
mechanical harvesting have diminished. For example, a temporary
reduction in dissolved oxygen may occur during harvesting, due to
sediment disturbance and suspension of decaying material in the
water.
Mechanical methods can be especially useful for removing portions
of dense mats of weeds. This creates weed-free refuge areas where the
fish would not be subjected to the low oxygen levels that can occur in
the thick mat of plants.
The time of year to stock grass carp depends primarily on availability
offish and on water quality. When the fish are used in conjunction with
herbicides or mechanical methods, stocking needs to be done prior to
regrowth of hydrilla but after the effects of these treatments have
dissipated.
The fish can be transported and handled much easier during cooler
months than during the hot summer months. Injured fish are less
susceptible to diseases when stocked in cool water rather than warm
water. Also, as discussed earlier, cool water contains more dissolved
oxygen than warm water.
In bodies of water with culverts or canals leading to other areas,
screens or gates must be installed to prevent escape of the grass carp.
Barriers need to be constructed so the fish cannot jump over them.
Screens (Figure 5) have proven effective in preventing movement of
grass carp while allowing unrestricted movement of water. This type of
barrier must have spaces between the bars narrower than the stocked
grass carp's body width.
Grass carp are extremely difficult to remove from a body of water.
Draining the water or using a fish toxicant such as Rotenone are two
ways to remove them.







Permit Requirements for Grass Carp
In Florida, a permit is required by law for use or possession of grass
carp. Only grass carp certified as triploid can be used in an aquatic
weed management program. Individuals interested in using grass carp
for aquatic weed management may contact the University of Florida
Cooperative Extension Service or the Florida Game and Freshwater
Fish Commission for assistance in stocking rates, suppliers of certified
triploid grass carp, and procedures for obtaining a permit. Application
for a permit may be obtained by writing the Florida Game and
Freshwater Fish Commission, Bureau of Fisheries Management, 620
S. Meridan St., Tallahassee, FL 32301.

Summary
Management of hydrilla and other aquatic weeds in many bodies of
water is possible with grass carp. An integrated management program
consisting of low stocking rates of fish combined with applications of
herbicides or mechanical control methods may be the best way to
reduce nuisance growth of weeds. This approach may also encourage
growth of desirable native aquatic plants. Converting unwanted weeds
to valuable fish protein is an additional benefit of using grass carp.

Additional Readings
Cross, D. G. 1969. Aquatic weed control using grass carp. J. Fish Biol. 1:27-30.
Shireman, J. V. and C. R. Smith. 1983. Synopsis of Biological Data on the
Grass Carp Ctenopharyngodon idella (Cuvier and Valenciennes, 1844).
FAO Fisheries Synopsis No. 135. 86 pp.
Sutton, D. L. 1974. Utilization of hydrilla by the white amur. Hyacinth Contr.
J. 12:66-70.
Sutton, D. L. 1977. Grass carp Ctenopharyngodon idella Val. in North
America. Aquatic Botany 3:157-164.
Swingle, H. S. 1957. Control of pondweeds by use of herbivorous fishes. Proc.
South. Weed Conf. 10:11-17.
Van Dyke, J. M. and D. L. Sutton. 1977. Digestion of duckweed (Lemna spp.)
by the grass carp Ctenopharyngodon idella. J. Fish Biol. 11:273-278.
Van Dyke, J. M., A. J. Leslie, Jr., and L. E. Nail. 1984. The effects of the grass
carp on the aquatic macrophytes of four Florida lakes. J. Aquat. Plant
Manage. 22:87-95.

Acknowledgments
The authors would like to thank W. B. Ennis, Jr., J. C. Joyce, C. L. Phillippy,
J. V. Shireman, J. G. Stanley, J. M. Van Dyke, and F. J. Ware for their critical
review of this article.







Permit Requirements for Grass Carp
In Florida, a permit is required by law for use or possession of grass
carp. Only grass carp certified as triploid can be used in an aquatic
weed management program. Individuals interested in using grass carp
for aquatic weed management may contact the University of Florida
Cooperative Extension Service or the Florida Game and Freshwater
Fish Commission for assistance in stocking rates, suppliers of certified
triploid grass carp, and procedures for obtaining a permit. Application
for a permit may be obtained by writing the Florida Game and
Freshwater Fish Commission, Bureau of Fisheries Management, 620
S. Meridan St., Tallahassee, FL 32301.

Summary
Management of hydrilla and other aquatic weeds in many bodies of
water is possible with grass carp. An integrated management program
consisting of low stocking rates of fish combined with applications of
herbicides or mechanical control methods may be the best way to
reduce nuisance growth of weeds. This approach may also encourage
growth of desirable native aquatic plants. Converting unwanted weeds
to valuable fish protein is an additional benefit of using grass carp.

Additional Readings
Cross, D. G. 1969. Aquatic weed control using grass carp. J. Fish Biol. 1:27-30.
Shireman, J. V. and C. R. Smith. 1983. Synopsis of Biological Data on the
Grass Carp Ctenopharyngodon idella (Cuvier and Valenciennes, 1844).
FAO Fisheries Synopsis No. 135. 86 pp.
Sutton, D. L. 1974. Utilization of hydrilla by the white amur. Hyacinth Contr.
J. 12:66-70.
Sutton, D. L. 1977. Grass carp Ctenopharyngodon idella Val. in North
America. Aquatic Botany 3:157-164.
Swingle, H. S. 1957. Control of pondweeds by use of herbivorous fishes. Proc.
South. Weed Conf. 10:11-17.
Van Dyke, J. M. and D. L. Sutton. 1977. Digestion of duckweed (Lemna spp.)
by the grass carp Ctenopharyngodon idella. J. Fish Biol. 11:273-278.
Van Dyke, J. M., A. J. Leslie, Jr., and L. E. Nail. 1984. The effects of the grass
carp on the aquatic macrophytes of four Florida lakes. J. Aquat. Plant
Manage. 22:87-95.

Acknowledgments
The authors would like to thank W. B. Ennis, Jr., J. C. Joyce, C. L. Phillippy,
J. V. Shireman, J. G. Stanley, J. M. Van Dyke, and F. J. Ware for their critical
review of this article.







Permit Requirements for Grass Carp
In Florida, a permit is required by law for use or possession of grass
carp. Only grass carp certified as triploid can be used in an aquatic
weed management program. Individuals interested in using grass carp
for aquatic weed management may contact the University of Florida
Cooperative Extension Service or the Florida Game and Freshwater
Fish Commission for assistance in stocking rates, suppliers of certified
triploid grass carp, and procedures for obtaining a permit. Application
for a permit may be obtained by writing the Florida Game and
Freshwater Fish Commission, Bureau of Fisheries Management, 620
S. Meridan St., Tallahassee, FL 32301.

Summary
Management of hydrilla and other aquatic weeds in many bodies of
water is possible with grass carp. An integrated management program
consisting of low stocking rates of fish combined with applications of
herbicides or mechanical control methods may be the best way to
reduce nuisance growth of weeds. This approach may also encourage
growth of desirable native aquatic plants. Converting unwanted weeds
to valuable fish protein is an additional benefit of using grass carp.

Additional Readings
Cross, D. G. 1969. Aquatic weed control using grass carp. J. Fish Biol. 1:27-30.
Shireman, J. V. and C. R. Smith. 1983. Synopsis of Biological Data on the
Grass Carp Ctenopharyngodon idella (Cuvier and Valenciennes, 1844).
FAO Fisheries Synopsis No. 135. 86 pp.
Sutton, D. L. 1974. Utilization of hydrilla by the white amur. Hyacinth Contr.
J. 12:66-70.
Sutton, D. L. 1977. Grass carp Ctenopharyngodon idella Val. in North
America. Aquatic Botany 3:157-164.
Swingle, H. S. 1957. Control of pondweeds by use of herbivorous fishes. Proc.
South. Weed Conf. 10:11-17.
Van Dyke, J. M. and D. L. Sutton. 1977. Digestion of duckweed (Lemna spp.)
by the grass carp Ctenopharyngodon idella. J. Fish Biol. 11:273-278.
Van Dyke, J. M., A. J. Leslie, Jr., and L. E. Nail. 1984. The effects of the grass
carp on the aquatic macrophytes of four Florida lakes. J. Aquat. Plant
Manage. 22:87-95.

Acknowledgments
The authors would like to thank W. B. Ennis, Jr., J. C. Joyce, C. L. Phillippy,
J. V. Shireman, J. G. Stanley, J. M. Van Dyke, and F. J. Ware for their critical
review of this article.







Permit Requirements for Grass Carp
In Florida, a permit is required by law for use or possession of grass
carp. Only grass carp certified as triploid can be used in an aquatic
weed management program. Individuals interested in using grass carp
for aquatic weed management may contact the University of Florida
Cooperative Extension Service or the Florida Game and Freshwater
Fish Commission for assistance in stocking rates, suppliers of certified
triploid grass carp, and procedures for obtaining a permit. Application
for a permit may be obtained by writing the Florida Game and
Freshwater Fish Commission, Bureau of Fisheries Management, 620
S. Meridan St., Tallahassee, FL 32301.

Summary
Management of hydrilla and other aquatic weeds in many bodies of
water is possible with grass carp. An integrated management program
consisting of low stocking rates of fish combined with applications of
herbicides or mechanical control methods may be the best way to
reduce nuisance growth of weeds. This approach may also encourage
growth of desirable native aquatic plants. Converting unwanted weeds
to valuable fish protein is an additional benefit of using grass carp.

Additional Readings
Cross, D. G. 1969. Aquatic weed control using grass carp. J. Fish Biol. 1:27-30.
Shireman, J. V. and C. R. Smith. 1983. Synopsis of Biological Data on the
Grass Carp Ctenopharyngodon idella (Cuvier and Valenciennes, 1844).
FAO Fisheries Synopsis No. 135. 86 pp.
Sutton, D. L. 1974. Utilization of hydrilla by the white amur. Hyacinth Contr.
J. 12:66-70.
Sutton, D. L. 1977. Grass carp Ctenopharyngodon idella Val. in North
America. Aquatic Botany 3:157-164.
Swingle, H. S. 1957. Control of pondweeds by use of herbivorous fishes. Proc.
South. Weed Conf. 10:11-17.
Van Dyke, J. M. and D. L. Sutton. 1977. Digestion of duckweed (Lemna spp.)
by the grass carp Ctenopharyngodon idella. J. Fish Biol. 11:273-278.
Van Dyke, J. M., A. J. Leslie, Jr., and L. E. Nail. 1984. The effects of the grass
carp on the aquatic macrophytes of four Florida lakes. J. Aquat. Plant
Manage. 22:87-95.

Acknowledgments
The authors would like to thank W. B. Ennis, Jr., J. C. Joyce, C. L. Phillippy,
J. V. Shireman, J. G. Stanley, J. M. Van Dyke, and F. J. Ware for their critical
review of this article.









































UNIVERSITY OF FLORIDA


This public tion %'as..pr.duced at an annual cost of $2,751.75 or
$.40 per c y to inform'in he public about the use of grass carp to
control a uatic weeds. : "

All programs and related activities sponsored or assisted by the Florida
Agricultural Experiment Stations are open to all persons regardless of race,
color, national origin, age, sex, or handicap.




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