UF/IFAS Blountstown aquaculture...
 Student involvement at UF
 Curbing cormorants
 UF/IFAS Fisheries and Aquatic Sciences,...
 New pond a big success
 UF/IFAS Fisheries and Aquatic sciences,...
 Dear editor

Group Title: Waterworks
Title: Waterworks. Volume 6, Number 1. 2002.
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00067314/00009
 Material Information
Title: Waterworks. Volume 6, Number 1. 2002.
Uniform Title: Waterworks
Physical Description: Serial
Creator: Institute of Food and Agricultural Sciences
Publisher: Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida
Publication Date: 2002
Funding: Florida Historical Agriculture and Rural Life
 Record Information
Bibliographic ID: UF00067314
Volume ID: VID00009
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 by the source institution and holding location.

Table of Contents
    UF/IFAS Blountstown aquaculture facility closed
        Page 1
    Student involvement at UF
        Page 2
    Curbing cormorants
        Page 3
    UF/IFAS Fisheries and Aquatic Sciences, aquaculture, and pond management updates
        Page 4
    New pond a big success
        Page 5
    UF/IFAS Fisheries and Aquatic sciences, aquaculture, and pond management update continued
        Page 6
    Dear editor
        Page 7
        Page 8
Full Text

University of Florida Cooperative Extension Service/Institute of Food and Agricultural Sciences Volume 6 Number 1 2002

April 4-5
Fi\li Health ll.lmiueinentl \or\lhoip
Tropical Aquacullure Lab / Ruskin
Roy Yanong 813/671-5230 x104

April 1 1
Praruite Idenuification Iorkliop
Tropical Aquacullure Lab / Ruskin
Roy Yanong 813/671-5230 x10I4

May 13
Pond iUlanagemeft Ii orklhoup fbr
Rural. And Recreational Pond Ownieric
Hardee County Civic Cenler/ Wakulla
John Brenneman 863/533-0765

May 13-24
L)i\amec ofi/'i r'(waler Fi\li
Tropical Aquacullure Lab / Ruskin
Whitney Lab / St. Augusline
Ruth Fian.:s-,-Flo:yd 352/392-9617 x229

May 19-24
. quatric II Cet Conrl -n I f
Short CourIII 2002 "
Fl. Lauderdale Research &
Education Cenler
Ft. Lauderdale Marriott North
Belh Miller Tipton 352/392-5930




Facility Closed
The Sam Mitchell Aquaculture Demon-
stration Farm in Blountstown is one of several
facilities that were closed due to severe
budget reductions imposed on UF/IFAS in the
wake of Florida's budget deficit. Budget call-
backs for the current fiscal year and large
cuts anticipated fo next year have resulted
in immediate closure or consolidation of both
on- and off-campus IFAS units. In conjunction
with the closure and reduction in these
facilities, many of the associated staff have
been laid off to meet the budget restrictions.
The aquaculture facility, part of UF/IFAS'
Department of Fisheries and Aquatic
Sciences (FAS), was opened in 1988 to
provide commercial fish farmers with the
latest technology and management practices
in foodfish and baitfish aquaculture. Through
the years, work at the 40-acre farm has
included applied production research and
demonstration on species such as sturgeon,
golden shiners, Gulf killifish, hybrid striped
bass, and fancy goldfish. The official closing
date for the Sam Mitchell Aquaculture
Demonstration Farm was February 28.
Equipment and supplies at the facility
have been moved to the Department's core
facility in Gainesville and to its Tropical
Aquaculture Lab in Ruskin for use in on-going
programs. Disposition of the property has
yet to be determined.

Debbie Britt Pouder, foreground, captures a
young sturgeon as Dave Carpenter, and
Randall Kent pull the fish net toward the shoreline
at the (former) Sam Mitchell Aquaculture
Demonstration Farm.

Though all staff positions associated with
the Blountstown facility were eliminated, FAS
is using temporary grant funding to retain
Debbie Britt Pouder as a Senior Biological
Scientist assisting with aquaculture extension
and applied research programs in the
Florida Panhandle. For general aquaculture
information, Debbie can be reached on
Monday's at the
Extension Office UNIVRSITA
in Panama City FLA
at 850/784-6105. In.ttue. of Food and Agscultural S ,ence

The following UF/IFAS
faculty and staff are
available to answer
questions or provide
technical support for
aquaculture, fisheries and
aquatic sciences, and
pond management.

Frank Chapman
Reproductive Biology
352/392-9617 ext 247
fac@gnv.ifas.uf .edu
Chuck Cichra
Pond Management &
Fish Biology
352/392-9617 ext 249
Ruth Francis-Floyd
Fish Health/Aquaculture
352/392-9617 ext 229
Ruth Ellen Klinger
Fish Health
352/392-9617 ext 230

Debbie Britt Pouder
Food & Bait Aquaculture

Eric Curtis
Fish Health
813/671-5230 ext 106
Craig Watson
Research Coordinator
813/671-5230 ext 107
Roy Yanong
Fish Health/Aquaculture
813/671-5230 ext 104
Carlos Martinez
Ornamental Fish
813/671-5230 ext 109

Ken Langeland
Aquatic Plants

Chuck Adams
Marine Economics
352/392-1826 ext 223

David Zimet
Freshwater Economics

Ray Bucklin
Aquaculture Engineering

John Brenneman
Polk/Hillsborough Counties
Max Griggs
Escambia County
Bill Mahan
Franklin County
Leslie Sturmer
Shellfish Aquaculture
Don Sweat
Pasco County

Allen Riggs
Fish Health
352/392-9617 x 235

Undergraduate and graduate students are an importantpart of the teaching, research,
and extension programs at the University of Florida. Student involvement is high-
lighted in each issue of WaterWorks.

Ed Sullivan received a
bachelor of science
degree in Marine Biology
from the University of
West Florida in May of
1999. That fall, he began
his graduate studies at
the University of Florida
under Dr. Debra Murie.
Ed was interested in
studying new manage-
ment techniques for
marine fisheries and
proposed the idea of
studying hatchery-reared
red drum in the wild.
Dr. Murie and co-
investigator Dr. Daryl
Parkyn were able to
secure funding for a
small project involving
the cooperation of Florida
Power and Light's (FP&L)
Mariculture Center and the
USGS Chassahowitzka
National Wildlife Refuge.
In the refuge, they
released approximately
20,000 juvenile red drum
into two creeks in June
of 2000. Subsequent to
the release (within the
first week) they observed
a high rate of disappear-
ance from the release
creeks. Based on
recapture locations and
ultra-sonic tracking of
tagged fish, fish that
survived the release
rapidly emigrated out of
the tidal creeks.
The project demon-
strated that both the
location of the release
site and the seasons are
important considerations
when releasing hatchery-
reared red drum into the
wild and tracking their
progress into a red drum
"Our original plan was
to release two-inch
fingerling redfish into the
refuge in the autumn,"
said Sherwood. "This

ca snerwood

would have been an in-
season release. However,
due to a variety of hatchery
constraints, we released
2.5-inch fingerlings during
June of 2000. This made it
an out-of-season release,
and allowed us to evaluate
it against in-season
Our results provide a
basic insight into the use
of supplemental stocking
as a management strategy
for red drum.
"We expected the fish
to move from the creeks,
but were surprised at just
how quickly they moved.
We assume that the
majority of fish left the
creeks (rather than died)
because we ultrasonically
tracked similar sized red
drum during the post-
release period and most
of these fish moved toward
the mouth of the creeks
before disappearing."
In June of 2001, Ed
began work at the Florida
Marine Research Institute
(FMRI) as a researcher in
the Fisheries Independent
Monitoring Program (FIM).
FIM tracks the relative

abundance of a variety
of marine fish and select
invertebrates within the
Tampa Bay estuary and
monitors the release of
hatchery-reared red
drum into the Alafia
River. The goal of the
study is to increase
recreational catches of
red drum in Tampa Bay
by 25 percent. Ed was
drawn to the project, as
it pertained to his
graduate work.
During his short time
with FMRI, Ed was
offered a position as a
Marine Research Assoc.
in November of 2001.
He is now working on
several projects including
a gear comparison study;
the Project Tampa Bay
study; an examination
of the distribution and
abundance of red drum
in three Florida estuaries;
and the development of
a temporal and spatial
model of red drum
within Tampa Bay.
"I enjoy my work
very much," says Ed.
"I'm in the field two or
three days a week and
have used a variety of
gear to capture and study
estuarine fish. I've
gained a tremendous
amount of field experience
and am starting to get
more involved with data
analysis. My long-term
goals are to be involved
with annual stock
assessments and
management decisions
of Florida's marine
fisheries. I think I can
accomplish these goals
here at FMRI." Ed is
currently writing his
Master's thesis and
hopes to defend it this
Dr. Debra Murie
352/392-9617 x 245

he U.S. Fish and Wildlife Service
recently released a draft Enviro-
mental Impact Statement (EIS) for
public review that will guide development
of a nationwide management strategy for
double-crested cormorants.
The EIS analyzes various options for
managing rapidly growing cormorant
populations-to reduce conflicts with
recreational anglers, commercial aquacul-
ture companies, and other human activities.
"The double-crested cormorant was given
Federal protection during serious population
declines in the 1970's. Today we face a
different problem as we seek to achieve
sustainable populations and reduce conflicts
with human activities," said Tom Melius, the
Service's assistant director for Migratory
Birds and State Programs.
Cormorants have been federally protected
by the Migratory Bird Treaty Act since 1972,
when they were given protection after their
populations dropped precipitously due to the
pesticide DDT killings by humans, and the
overall declining health of many ecosystems,
especially the Great Lakes. Today the
population is at historic highs, due in large
part to the presence of ample food in their
summer and winter ranges, federal and state
protection, and reduced contaminant levels.
Between 1970 and 1991, in the Great
Lakes region of the U.S. and Canada, the
number of double-crested cormorant nests
increased from 89 to 38,000, with an
average annual increase of 29 percent. By
1997, the Great Lakes population reached
approximately 98,000 pairs. The total
population of double-crested cormorants in
the U.S. and Canada has most recently been
estimated at some 2 million birds.
The population resurgence of double-
crested cormorants has led to increasing
concern about the bird's impact on commer-
cial and recreational fishery resources.
The draft EIS evaluates six management
alternatives, including such options as
continuing current management practices,
implementing only non-lethal management
techniques, issuing a new Depredation
Order to address public resource conflicts
(the Service's proposed alternative) and
establishing frameworks for a cormorant
hunting season.
Cormorants and other waterbirds such as
pelicans and herons can have adverse
impacts on fish populations when fish are
concentrated in artificially high numbers-

conditions such as those found at fish
farms, hatcheries, and sites where hatch-
ery-reared fish are released. The Service
has previously taken action to protect fish in
these situations.
In 1998, the Service issued a Depredation
Order authorizing commercial freshwater
aquaculture producers in 13 states including
Florida, to take this species of cormorant
without a federal permit, when the birds
were found committing or about to commit
depredations to aquaculture stocks.
The Depredation Order states that
double-crested cormorants may be taken by
shooting only during daylight hours, and
only when necessary to protect freshwater
commercial aquaculture and state-operated
hatchery stocks and that such actions must
be carried out in conjunction with a non-
lethal harassment program.
The 1998 Order does not address
impacts on commercial and recreational
fisheries. The effect of cormorants on fish
populations in open waters is less clear than
at aquaculture facilities. In some cases,
research suggests that cormorants appear
to be capable of taking numbers of sport
fish significant enough to have a negative
impact on catch rates.
The Service believes that at this time,
there is no sufficient scientific evidence to
justify controlling cormorants on a national
level to benefit open water commercial
fisheries. Where site-specific problems are
significant, the Service's practice is, and will
continue to be, to issue depredation permits
to alleviate conflicts outside the authority of
the depredation orders.
The Service's proposed action would
establish a new Depredation Order authoriz-
ing state, tribal and federal land management
agencies to implement a double-crested
cormorant management program while main-
taining Federal oversight of populations via
reporting and monitoring requirements to
ensure sustainable populations.
Control activities carried out under this
new depredation order would take place on
public and private lands and waters where
these cormorant populations are demon-
strably having a negative impact on public
Under this action, the 1998 Aquaculture
Depredation Order would continue to allow
cormorants to be taken at commercial
freshwater aquaculture facilities and state-
owned fish hatcheries in 13 states and




Double-crested cormorant
would be expanded to include winter roost
control by the U.S. Department of
Agriculture's Wildlife Services Program in
those states. A service regulation prohibiting
lethal control of cormorants under most
circumstances at National Fish Hatcheries
would be revoked.

Requests for copies of the draft
Environmental Impact Statement
should be mailed to:
Chief/Division of Migratory Bird Mgmt.
U.S. Fish and Wildlife Service
4401 N. Fairfax Drive, Room 634
Arlington, VA 22203
Copies can also be downloaded from the
Division of Migratory Bird Management
web site at:



Institute of Food and Agricultural Sciences

WaterWorks is published by UF/IFAS
Department of Fisheries and Aquatic
Sciences. Subscriptions are free. (See the
subscription form on page 8.) Questions,
comments or editorial submissions may
be submitted by contacting:
Editor Joe Richard
352/392-9617 ext 225
Faculty Advisor Chuck Cichra
352/392-9617 ext 249
Web site: http://fishweb.ifas.ufl.edu/

UAFAS Fis heri es a Aquatic Scenes Aquac *lture

and Pon Maaemn Update..


Cedar Key
Clam farmers (and anyone else for that
matter) can now go on-line to check
current water quality and weather data
conditions at a select number of offshore
clam leases off Florida's Gulf Coast.
"Real-time" equipment, installed by
UFIFAS' Dept. of Fisheries and Aquatic
Sciences and the Dept. of Agriculture and
Consumer Services' (DACS)/Division of
Aquaculture, is transmitting data to the
Division's web site:
So far, three of four sets of scientific
equipment have been installed near
commercial clam culture leases. One is
located on the Gulf Jackson lease, another
on the Horseshoe Lease. Both are high
density leases located near Cedar Key.
A third unit is in the Aquaculture Use Zone
near Sebastian and a fourth unit is
scheduled for the Charlotte Harbor area.
Installation of the equipment is an integral
component of CLAMMRS (Clam Leasing
Assessment, Management and Modeling
using Remote Sensing).

CLAMMRS is a four-year study by UF/IFAS'
Dept. of Fisheries and Aquatic Sciences
and the Dept. of Environmental Engineering,
with the goal of developing a production
model that identifies optimum clam farming
practices and monitors changes in their
natural food abundance and quality. The
model, along with an improved understand-
ing of hard clam nutrition and physiological
requirements, will help identify optimum
sites for leases. The data can also be
used by farmers to document crop losses,
should they occur, for financial assistance.
Workshops will be held this Spring, by
UF/IFAS' Shellfish Aquaculture Extension
Program and DACS' Division of Aquaculture,
to describe the value and practical
interpretation of this information. Also, the
Division is seeking commercial clam
farmer's comments on how best to
present the information on their web site.
Leslie Sturmer

Dept. of Fisheries and

Aquatic Sciences
You've got sick fish on your hands.
Who do you call? The following
individuals are a good place to start:
Commercial Fish Farm Production
Dr. Roy Yanong
UF Tropical Aquaculture Lab / Ruskin
Call 813/671-5230 x 104
Pet Fish and Koi
Dr. Allen Riggs
UF College of Veterinary Medicine
352/392-4700 x 5686
Game and Recreational Fish
Dr. Ruth Francis-Floyd
Dept. Fisheries & Aquatic Sciences/Gainesville
352/392-9617 x 229
Ruth Ellen Klinger
352-392-9617 x 230
Dept. Fisheries & Aquatic Sciences/Gainesville

Exotic Fish I
from UF
Campus Pond-
A reproducing population of exotic
convict cichlids Cichlasoma nigrofasciatum
was recently eradicated from Green Pond,
near the J. Wayne Reitz Union, on the
University of Florida (UF) main campus.
The cichlids are small tropical fish (<5 inch),
native to Central America, that have
managed to survive Gainesville's winter
temperatures due to the constant inflow of
warm water from the Reitz Union's heating
and cooling system.
The Florida Fish and Wildlife Conservation
Commission (FWC) requested that Green
Pond be renovated to remove the convict
cichlids the only reproducing population
in Florida. Personnel from UF/IFAS' Dept. of
Fisheries and Aquatic Sciences, under the
direction of Dr. Chuck Cichra, conducted the
effort, with assistance from the FWC and
Florida Museum of Natural History The
pond will be restocked with native fishes.
Over 1,000 convict cichlids were removed
along with two other exotic fish species, two
black pacu Colossoma macropomum and a
single oscar Astronous It's unknown
exactly how these exotic fish ended up in
the pond, but all are popular aquarium fish.
(It's illegal to release any non-native fish into
open waters of Florida.) Regardless of how
they got there, it is the legal responsibility of
the landowner to keep these fish out of the
water. In this case, UF had the honors. The
FWC, which has regulatory and enforce-
ment authority over exotic fishes, worked
closely with UF to remove the fish.
Florida has several species of exotic
fishes that have established reproducing
populations. Most of them are undesirable
and represent potential problems for native
species. Green Pond is being used as an
example, for the University community and
the public, of the legal, environmental, and
ethical issues involved in fish introductions.
Extension materials, and a series of popular
and scientific articles are currently under
development. Signs discouraging fish
releases will also placed near UF ponds.
Look for more information in the next issue
of WaterWorks.
Jeff Hill
352/392-9617 x 236

New Pond A Big Success

Despite early morning rain and chilly
conditions, a crowd of 455 anglers
converged on the ponds at the UF/IFAS
Department of Fisheries and Aquatic
Sciences, for the fourth annual Fishing For
Success (FFS) Law Enforcement Appreciation
Day. The February 16 event was the first of
many FFS Family Fishing Days scheduled
for the coming months, and the fishing was
fast and furious throughout the morning.
This first FFS event of the year held a new
exciting attraction. Watson Construction and
other local businesses recently combined efforts
to construct a new half-acre pond for FFS, to
compliment its many quarter-acre ponds.

Fishing for Success Coordinator Torn Glancy
stocks the new fishing pond at UF's Dept. of
Fisheries and Aquatic Sciences.

The new pond was built to replace the
one-acre pond on USGS property, which
had previously been used for fishing events,
but is now off-limits to the public, due to the
events of Sept. 11.
In preparation for this year's events, the
new pond was stocked with hundreds of
large catfish (up to 30 pounds), nearly 1,000
sunshine bass, and thousands of bluegills.
The Florida Fish and Wildlife Conservation
Commission (FWC) donated sunshine bass,
and the catfish and bluegills were moved
from the old USGS pond to their new home.
FFS staff are hoping to raise the necessary
funds to build a handicap-access dock
adjacent to the new pond in the near future.
On Feb. 16, scores of kids hurried out to
the new pond and the result was continuous
fishing action punctuated by the screaming
of overloaded reels and excited children.
Several big fish were hooked briefly but no
one landed any of the 25-30 pound catfish.
Little Nikki Bennett, age 4, captured the
"most fish" trophy by reeling in 68 bluegills
and sunshine bass in three hours, with only
minimal help from her father Greg.
In addition to its Family Fishing Days,
FFS also hosts many educational field trips
for area schools and church groups. Last
year, more than 9,800 people participated in
FFS programs, and attendance is expected
to increase again this year.

Sean Phinney, age 11, won the trophy for
S Fish with a 16.1-pound channel
Which he managed to land in spite of a
separated shoulder WaterWorks editor Joe
Richard wrestles with the brute.
The new, bigger fish pond will certainly
help absorb some of the fishing pressure.
Somewhere in that new pond lurks "General
Sherman," a monster 30-pound catfish. With
the standing FFS policy of catch and release,
"The General" will surely give more than a
few youngsters the fight of a lifetime in the
coming years.
Tom Glancy
392-9617 x 270

A~ -F -TT *=~'~ Ag

Ag/1FAS Fiheie and Aut Sciences,



Varies Widely

U lorida lake fisherman have
often wondered why the black
crappie, a popular panfish, is
abundant one year and not
the next. Do overall crappie
populations change that much? It would
seem so.
Recent studies conducted by UF/IFAS
fisheries researchers indicates that
Florida's black crappie fishery fluctuates
considerably due to a highly variable
recruitment each year. ("Recruitment"
refers to the production and survival of
young fish.) This variation contributes to a
"boom and bust" fishery later when
crappie grow large enough to be caught
by anglers.
Dr. Mike Allen and his team of graduate
students at UF's Department of Fisheries
and Aquatic Sciences have been investigat-
ing black crappie recruitment for the last
five years in Florida, with the following

Winter severity may influence black
crappie recruitment.
For example, in Lake Wauberg in north
central Florida, graduate student Bill Pine
found that early-hatched black crappie

UF/IFAS grad students Kevin Dockendorf and Kristin
examine a black crappie caught in their trawl on Lake

Black crappie (Pomoxis nigromaculatus)

that were subjected to cold water tempera-
tures (e.g., resulting from a late-season
cold front), experienced slower growth and
higher mortality, compared with late-hatched
fish in the same lake.

Black crappie growth is dependent on
their density in some lakes.
Graduate student Kevin Dockendorf
found that high densities (number of fish
per acre) of young black
crappie in Lakes Lochloosa
and Wauberg led to slower
fish growth, causing these
fish to take much longer,
three to four years, to grow
S big enough to be caught.
S Conversely, in the years
2000-2001, young black
crappie in Lake Tarpon had
low densities and the fish
grew quickly, requiring only
two years to grow to
harvestable sizes. These
observations have important
implications for the black
Henry crappie fishery. In lakes with
Wauberg. high densities, fishery

managers may be able to ease harvest
regulations by increasing bag limits.
That way, anglers can help reduce fish
numbers and hopefully increase fish
growth. Lakes with low-density popula-
tions could be managed with stricter bag
limits that will, in turn, help preserve the
low numbers of fast-growing fish, eventu-
ally building a quality fishery.
On the subject of crappie, a long-term
cooperative study is now being conducted
with the Florida Fish and Wildlife Conser-
vation Commission and the UF/IFAS Florida
LAKEWATCH program.
LAKEWATCH volunteers monitor water
quality on the lake they live on, and send
in samples to the University each month.
Participating volunteers will harvest crappie
from 15 Florida lakes each autumn. The
goal is to document trends in the number
of young fish as the years go by. Combined
with water sampling, it's hoped this study
will provide an indication of how changes
in water levels and aquatic plant growth
may also be influencing this fishery in
Dr. Mike Allen
352/392-9617 x 252

Dear Editor,
Below is a photo I took of a
plecostomus from Lake Marian at
Kenansville, Florida last year ...while
stopped there, I noticed several fish
belly-up and others dying in the small
pockets of water in the almost dry
canal. I walked over and found not a
few, but hundreds of these fish dying.
(It was a few days after the coldest
weather last year in Florida).
We then traveled a mile or two to
Lake Jackson. While there, we found
hundreds of dead or dying
plecostomus. This caused me to
wonder about other areas, as it was
obvious that Kissimmee and its canals
are infested with them. Two days later
we took a trip to the Peace River at
Zolfo Springs. It was also down very
low, and we found many dead and
dying plecostomus there. We then
traveled to Arcadia, and it was the
same there.
I raised two of these fish in a 110-
gallon aquarium to adult size. When
my cichlids laid eggs in the aquarium,
the plecostomus would eat the eggs if
possible. Since the pleco has natural
armor and a taste for fish eggs, is it
possible the deterioration of fish
populations in Florida lakes is related
to these voracious catfish?
Frank Hamill
Dear Frank,
Your observations of numerous dead
and dying pleco catfish over the winter
match those reported by fisheries
biologists and the public. These fishes
are tropical in origin and cold winter
temperatures will cause partial or total kills.
Florida has several established exotic
(i.e., foreign) fishes, including pleco
catfish. Plecos belong to the South
American fish family Loricariidae, the
armored suckermouth catfish. Members
of this family are often called plecos in
the aquarium fish trade. Florida has
members of at least two genera,
Hypostomus, armored suckermouth
catfish, and Pterygoplichthys, sailfin
catfish. The sailfin catfish are more
widespread and occur in much of
peninsular Florida, including the upper
St. Johns River and west coast streams
north of Tampa Bay, southward to the
canals of southeast Miami-Dade County.
The range of plecos has increased in
Florida in recent years and, as you have
seen, they may reach high densities.
As a group, plecos feed mainly on
algae and detritus (organic material)
from the bottom. Some species are more

carnivorous than others, but the species
established in Florida mainly eat this typical
pleco diet. I have maintained plecos of various
species in aquaria and also observed them
feeding on shrimp pellets, other fish food
pellets, dead fish, and fish eggs. In most
cases, cichlid fishes are able to successfully
raise young in the presence of plecos, but an
occasional individual pleco may develop a
habit of eating undefended or exposed fish
eggs. This behavior is also found in many
types of fishes (e.g., native sunfish Lepomis
spp.). Moreover, food items of captive fish are
not necessarily reliable indicators of diets in
natural habitats. For example, nearly any fish
large enough will eat the small eastern
mosquitofish Gambusia in an
aquarium, regardless of normal food selection
in the field.
Like you, I have often wondered about the
role of plecos as nest predators of exotic
cichlids and native sunfishes in Florida.
Nevertheless, based on a fair amount of
aquarium observations and limited field
observations, I suspect that plecos may not be
a significant limiting factor to nesting success
of these fishes. Even in confined aquaria,
cichlids in particular seem quite capable of
nest defense against plecos. I have even had
plecos injured or killed by nesting cichlid parents.
On the other hand, nighttime nest predation
could occur. The fact is that no one has
researched this topic, an undertaking that
would require carefully controlled laboratory
and field experiments.
You have also identified a perceived
problem, namely reduced harvest of fish from
Florida lakes, and suggested a mechanism to
explain it egg predation by plecos reducing
fish recruitment. In science, we call this a
hypothesis, a testable possible explanation for
an observed phenomenon. First, we would
need to clarify if the problem is real or just
apparent by reviewing historic fish and fishery
data and conducting research to assess
current fish populations. If the problem is real,
we move to the next step. According to the
scientific method, we would make predictions
based on this explanation and devise tests to
attempt to disprove this hypothesis. That is
right, attempt to disprove it. We do not prove
hypotheses in science, but gain confidence in
an explanation based on numerous failed
attempts to demonstrate that it is false.

What else may be a cause of the
decline of a fishery?
Numerous possibilities come to mind -
drought, muck build up, excessive aquatic
plants, summer fish kills due to low dissolved
oxygen, lack of food for larval or juvenile
fishes, overharvest, etc. You see, there are
many possible explanations that would require
study, not just plecos eating fish eggs.
Although exotic fishes have been prominent

in the state since the 1950s, relatively
few researchers have studied them. The
Florida Fish and Wildlife Conservation
Commission (FWC) has regulatory and
enforcement authority over exotic fishes
in open waters and has for many years
maintained a monitoring and research
program in south Florida. Recently, UF's
Department of Fisheries and Aquatic
Sciences of the University of Florida, the
U.S. Geological Survey, Florida Interna-
tional University, and individual research-
ers in other institutions are directing effort
towards exotic fishes in Florida.
The release of non-native fishes into
open waters in Florida is illegal, and the
FWC attempts to eradicate new
introductions if possible. Once an exotic
fish becomes established, however, it is
generally not feasible to attempt
eradication. It is clear that pleco catfish
are firmly established in Florida and
beyond eradication.
Many people assume that exotic
fishes have caused widespread harm to
Florida's native fishes. Contrary to this
opinion, there is almost no scientific
documentation that exotic fishes have
caused such harm. It is an unfortunate
fact that little research has been
conducted concerning interactions
between native and exotic fishes in
Florida. On the other hand, there has
been an accumulation of large amounts
of qualitative fishery data and some
quantitative data that is useful for
assessing the overall status of native
fish populations in areas affected by
exotic fishes.
The conclusion from these data is
that widespread catastrophic effects
have not occurred. This is not to say that
exotic fish are "good," nor are they
inherently "bad." Nearly everyone
agrees that exotic fishes are generally
undesirable and that much research is
needed to
determine the
effects that
exotic fishes
may have in
Jeff Hill

No Available

Beine' Gude to Wae Management

In an ongoing quest to bridge the
information gap between the scientific
community and Florida's citizenry, UF/
IFAS' Florida LAKEWATCH program
has assembled a series of information
circulars designed to provide an
introduction to the terminology and
concepts used in water management.

A Beginners Guide to Water
Management The ABCs
(Circular 101)
Formatted as a glossary, this booklet
provides definitions and additional
information for much of the terminology
used in water management. Enhanced
with dozens of black and white photos,
the circular is 39 pages in length, covering
subjects from A to Z (i.e., algae, average
plant biomass, limiting nutrients, potassium,
trophic state, and water quality to name
a few).
Now available on the UF/IFAS EDIS
website: http://edis.ifas.ufl.edu/fa078

A Beginner's Guide to Water
Management Nutrients
(Circular 102)
Nutrients are substances required by all
organisms for growth, and they're found in
every aquatic system. They are also the

object of much discussion by lake managers and
the general public, who are concerned about
the influence nutrients sometimes have on the
growth of algae and/or aquatic plants. Written
for a lay audience, this information circular is
an ideal reference booklet for students and/or
professionals interested in water management.
It's thirty-two pages in length, with many
supporting graphs and photos.
Now available on the UF/IFAS EDIS
website: http://edis.ifas.ufl.edu/fa079


For a free subscription to WaterWorks please complete the following form
and send it or fax it to the address below.

PLEASE Check One:

Please add my name to your mailing list.

Please remove my name from your mailing list.



Copy or clip out order form and send to: .t of
Editor I WaterWorks
University of Florida .
Department of Fisheries and Aquatic Sciences 1D
PO Box 110600
Gainesville, FL 32611-0600
Phone: 352/392-9617 ext. 225 Fax: 352/392-3672
E-mail: fishweb@gnv.ifas.ufl.edu
Website: http://fishweb.ifas.ufl.edu/

A 0966Mu bGump S*

---IIIIIIII ----------------------------- ElI

A Beginner's Guide to Water
Management Water Clarity
(Circular 103)
Water clarity is one of the most notice-
able attributes of a waterbody In Florida, a
wide range of water clarity occurs naturally
in lakes and waterbodies. This booklet is 33
pages in length and includes numerous
photographs and figures. Topics include:
measuring water clarity and what affects it;
the relationship between water clarity and
biological productivity; and techniques used
for managing clarity in lakes. Mathematical
models are also introduced as a way of
predicting water clarity in lakes.
Now available on the UF/IFAS EDIS
website: http /edis.ifas.ufl.edu/fa080
Printed copies are available by contacting
your local UF/IFAS Cooperative Extension
Service or from the LAKEWATCH program
itself. (Quantities may be ordered at cost.)
They may also be downloaded for free by
visiting the UF/IFAS EDIS website addresses
provided here or from the Florida LAKEWATCH
website listed below:
1-800-LAKEWATCH (525-3928)




Institute of Food and Agricultural Sciences
The Institute of Food and
Agricultural Sciences is an Equal
Employment Opportunity -
Affirmative Action Employer
authorized to provide research,
educational information and other
services only to individuals and
institutions that function without
regard to race, color, sex, age,
handicap or national origin.
Inclusion of material in this
newsletter does not constitute
endorsement, nor does exclusion
represent censure of any item,
organization, individual, or
institution by the University of
Florida/Institute of Food and
Agricultural Sciences.


University of Florida Home Page
© 2004 - 2010 University of Florida George A. Smathers Libraries.
All rights reserved.

Acceptable Use, Copyright, and Disclaimer Statement
Last updated October 10, 2010 - - mvs