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LIBRARY
Michigan State
Unlverslty

 

 

 

This is to certify that the

thesis entitled

EVALUATION OF FEEDING STRATEGIES FOR FIRST-FEEDING YELLOW
PERCH (PERCA FLAVESCENS) FRY; GENDER EFFECTS ON
BIOENERGETIC RESPONSES OF YELLOW PERCH FINGERLINGS

presented by

Jon J. Amberg

has been accepted towards fulﬁllment
of the requirements for

M.S. degree inFisheries 5: Wildlife

 

0-7639 MS U is an Aﬂirmative Action/Equal Opportunity Institution

 

 

 

PLACE IN RETURN BOX to remove this checkout from your record.
To AVOID FINES return on or before date due.
MAY BE RECALLED with earlier due date if requested.

 

DATE DUE DATE DUE DATE DUE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

6/01 c:/CIRC/DateDue.p65—p.15

 

EVALUATION OF FEEDING STRATEGIES FOR FIRST-FEEDING YELLOW
PERCH (PERCA FLAVESCENS) FRY; GENDER EFFECTS ON
BIOENERGETIC RESPONSES OF YELLOW PERCH FINGERLINGS
By

Jon J. Amberg

AN ABSTRACT OF A THESIS
Submitted to
Michigan State University
in partial fulﬁllment of the requirements
for the degree of
MASTER OF SCIENCE
Department of Fisheries and Wildlife
2001

Dr. Donald Carling Jr.

ABSTRACT
EVALUATION OF FEEDING STRATEGIES FOR
FIRST FEEDING YELLOW PERCH FRY
AND GENDER EFFECTS ON BIOENERGETIC RESPONSES OF
YELLOW PERCH GREATER THAN 15 CM
By

Jon J. Amberg

F irst-feeding yellow perch fry were fed Artemia nauplii, vinegar eels,
Artiﬁcial PlanktonTM or combinations of the feeds in 15 l green experimental tanks.
Mortality rates were 100% due to failure of inﬂate the swim bladder. However,
survival of fry in the holding tank exceeded 75% to 25 mm total length and a high
percentage of swim bladder inﬂation was observed. The 378 I gray holding tank
had an increased surface area to volume ratio and a less turbulent ﬂow pattern.

A saturation kinetics model was used to describe the growth rates of all-
female (AF) and predominately-male (PM) yellow perch stocks fed varying ration
levels (0.5, 1.0, 2.0, or 3.0% wet-weight per day). The growth of the AF stock was
signiﬁcantly greater than the PM stock when ﬁsh were fed at 3% body weight per
day. At ration levels of 2% body wet weight per day or less, the growth rates of
both genders were not Signiﬁcantly different. The proximate analysis of whole ﬁsh
tissues did not differ between genders or ration levels. The greatest digestion

efﬁciencies were observed for the 1.0-% ration level for both gender stocks.

Dedication

This body of work is dedicated to my family Janet J. Amberg, Edwin E.
Amberg, and Laura L. Turley for their guidance in my life. I would also like to
dedicate this work in the memory of my late grandparents, Carl and Marie
Amberg. Both of who passed away after its inception, but before its completion.
Although they were unable to see its culmination, I know they were present with

me in spirit. Thank you for the guidance in my life.

iii

 

ACKNOWLEDGMENTS

I wish to extend my deepest and sincerest gratitude to Dr. Donald Carling
Jr. who had the faith and patience to guide me though this research and this
program. He has been a mentor that has allowed me the opportunities to grow
and develop personally and professionally. He has extended his hand as a true
friend. I would also like to extend my gratitude to my graduate committee Dr.
Robert Batie and Dr. Michelle Kopcha for their assistance and advice.

A special thanks to Dr. L. Preston Mercer (Nutrition Department,
University Of Kentucky at Lexington) for his assistance and providing the
Saturation Kinetic Model software that was vital for the completion of this
research.

I would like to give a big thank you to my dear friends Martin Riche and
Steven Hart for their assistance in sample collection and analysis. I am also
grateful to Dr. S. Jerrine Nichols and Dr. James Hickey of the Great Lakes
Science Center, both of whom allowed me the freedom to ﬁnish this project. I
would like to acknowledge Dr. Nathalie Trottier, Robert Burnett and David Main
of the Animal Science Department at Michigan State University for their
cooperation and assistance, without it I could not have ﬁnished.

To my beautiful bride-to—be, Shannon Milanowski, I say thank you for your

love and support. I promise to pay you back for your tireless patience and

kindness you have demonstrated during this period. Thank you for picking me

up when I had fallen.

 

This research was funded by the North Central Regional Aquaculture

Center.

 

 

TABLE OF CONTENTS
LIST OF ABBRVIATIONS ................................................................... viii
LIST OF TABLES ................................................................................. x
LIST OF FIGURES .............................................................................. xii
INTRODUCTION ................................................................................. 1
HYPOTHESIS STATEMENTS ................................................................ 4
LITERATURE REVIEW ......................................................................... 5

CHAPTER ONE: Evaluation of Feeding Strategies for First-Feeding Yellow

Perch (Perca ﬂavescens) Fry.

INTRODUCTION ................................................................................. 12

LITERATURE REVIEW ......................................................................... 15
MATERIALS AND METHODS

Trial One ................................................................................... 21

Trial Two ................................................................................... 24

Trial Three ................................................................................. 24

Trial Four ................................................................................... 25

RESULTS .......................................................................................... 27

DISCUSSION ...................................................................................... 31

SUMMARY AND CONCLUSION ............................................................. 36

CHAPTER TWO: Gender Effects on Bioenergetic Responses of Yellow
Perch (Perca ﬂavescens) Fingerlings.

INTRODUCTION ................................................................................. 38
LITERATURE REVIEW ......................................................................... 40

vi

 

 

Gender Identiﬁcation ................................................................... 40
Gender-Related Growth Differences ............................................... 40
Saturation Kinetics Model ............................................................. 43
MATERIALS AND METHODS
Secondary Sex Characteristics ...................................................... 52
Saturation Level Kinetics ............................................................... 53
System and Water .............................................................. 53
Fish ................................................................................. 55
Feed and Feeding Trials ...................................................... 56
Proximate Analysis ............................................................. 57
Statistical Analysis .............................................................. 58
RESULTS
Secondary Sex Characteristics ...................................................... 59
Saturation Level Kinetics ............................................................... 61
Growth ............................................................................. 64
Crude Protein .................................................................... 68
Crude Lipids ..................................................................... 70
Energy ............................................................................. 72
Ash ................................................................................. 74
DISCUSSION
Secondary Sex Characteristics ...................................................... 75
Saturation Level Kinetics ............................................................... 76
Proximate Analysis ...................................................................... 78
SUMMARY AND CONCLUSION ............................................................ :89
BIBLIOGRAPHY .................................................................................. 91
APPENDIX 1 ..................................................................................... 102
APPENDIX 2 ..................................................................................... 103
APPENDIX 3 ..................................................................................... 104
APPENDIX 4 ..................................................................................... 105

vii

 

LIST OF ABBREVIATIONS

AA -— Amino acids
AF - All female
5 - Intercept on the ordinate y-axis
BW - Body weight
CP —- Crude protein
CL - Crude lipid
DE — Digestible energy
DM - Dry matter
E -— Gross energy
EE - Energy efﬁciency
EL -- Eye diameter/length
FE - Feed efﬁciency
GPM - Gallons per minute
I - Nutrient intake
Km - Intake constant for 1/2 of Rmax

Ks - Substrate concentration level at which the growth is 1/z umax
LPM — Liters per minute
MH - Mouth height

ML - Maxillary length

MS-222 — Tricainemethane sulfonate

MW —— Mouth width

viii

 

n - Slope factor (compared to Km. apparent kinetic order of the response with
respect to I as In becomes negligible)

NCRAC - North Central Regional Aquaculture Center
PM — Predominately male

ppm - Parts per million

r - Physiological observed responses

Rmx - Maximum response

S - Substrate concentration level

SBI - Swim bladder inﬂation

SD - Standard deviation

SEM - Standard error of the mean

ST — Standard length

TL - Total length

YPFFF - Yellow perch ﬁrst-feeding fry

p. - Growth rate (1/time)

lJ'max - Maximum growth rate (1/time)

ix

LIST OF TABLES

Table 2.1--- The mean, standard error of the mean, and standard deviation for
eye diameter (ED), maxillary length (ML), mouth width (MW), mouth height (MH),
total length (TL), and standard length (SL) by gender for yellow perch (Perca
flavescens), as well as the ratios between ED, ML, MW, and MH to SL and

TL ..................................................................................................... 60

Table 2.2-- Proximate analysis, on dry matter basis, of a commercial feed,
Purina Aquamax Grower 400 (lot A-5d04) and :tSEM that was fed at ration levels
of 0.5, 1.0, 2.0, and 3.0% body-wet weight per day for 112 days to a
predominately-males stock and an all-female stock of yellow perch (Perca
flavescens) ......................................................................................... 62

Table 2.3--- Parameter estimates for Mercer's saturation level kinetic model for
yellow perch (Perca ﬂavescens) (141 .5:I:1 1 .6 mm TL) fed at ration levels of 0.5,
1.0, 2.0 and 3.0% body weight per day for 112 days. Basal metabolic
maintenance level is Ir=o, and optimal feeding level is Imx ............................... 66

Table 2.4-«- Mean feed efﬁciencies (weight gained/weight fed) and iSEM of
predominately-male and all-female stocks Of yellow perch (Perca ﬂavescens)
(141.5:11.6-mm TL) fed ration levels of 0.5, 1.0, 2.0, and 3.0% body-wet weight
per day for 112 days. Corresponding letters indicate no statistical difference
between means (p>0.05) ....................................................................... 67

Table 2.5--- Mean crude protein levels (% dry matter) and :tSEM of
predominately-male and all-female stocks of yellow perch (Perca ﬂavescens)
(141.5:11.6-mm TL) fed ration levels of 0.5, 1.0, 2.0, and 3.0% body-wet weight
per day. NO statistical difference was identiﬁed between means (p>0.05)...... . ..69

Table 2.6—-- Mean protein efﬁciencies (protein gained/dietary protein) and iSEM
of predominately-male and all-female stocks of yellow perch (Perca ﬂavescens)
(141.5i11.6-mm TL) fed ration levels of 0.5, 1.0, 2.0, and 3.0% body-wet weight
per day. Corresponding letters indicate no statistical difference between means
(p>0.05) .............................................................................................. 69

Table 2.7--- Mean crude lipid levels (% dry matter) and :tSEM of predominately-
male and all-female stocks of yellow perch (Perca ﬂavescens) (141.5:t11.6-mm
TL) fed ration levels of 0.5, 1.0, 2.0, and 3.0% body-wet weight per day. NO
statistical difference was identiﬁed between means (p>0.05) ......................... 70

Table 2.8—— Mean lipid efﬁciencies (lipid gained/dietary lipid) and :tSEM of
predominately-male and allvfemale stocks of yellow perch (Perca ﬂavescens)
(141.5i1l.6-mm TL) fed ration levels of 0.5, 1.0, 2.0, and 3.0% body-wet weight

per day. Corresponding letters indicate no statistical difference between means
(p>0.05) .............................................................................................. 70

Table 2.9-"- Mean energy levels (Kcal/gram) and iSEM of predominately-male
and all-female stocks of yellow perch (Perca ﬂavescens) (141.511 1.6-mm TL) fed
ration levels of 0.5, 1.0, 2.0, and 3.0% body-wet weight per day. Corresponding
letters indicate no statistical difference between means (p>0.05) .................... 73

Table 2.10“» Mean energy efﬁciencies (Kcal gained/dietary energy) and :SEM
of predominately-male and all-female stocks of yellow perch (Perca ﬂavescens)
(141.5:11.6-mm TL) fed ration levels 010.5, 1.0, 2.0, and 3.0% body-wet weight
per day. Corresponding letters indicate no statistical difference between means
(p>0.05) .............................................................................................. 73

Table 2.11»— Mean ash levels (% dry matter) and :SEM of predominately-male
and all-female stocks of yellow perch (Perca ﬂavescens) (141.5:11.6-mm TL) fed
ration levels of 0.5, 1.0, 2.0, and 3.0% body-wet weight per day. Corresponding
letters indicate no statistical difference between means (p>0.05) .................... 74

xi

LIST OF FIGURES

Figure 1.1--— Center drain tube made of 2-inch PVC pipe with the sides cut out
and holes covered with 300-um Nitex screening ......................................... 22

Figure 1.2 -- Percent survival for ﬁrst-feeding yellow perch fry of Trial-1 fed
Artemia nauplii, vinegar eels, Artiﬁcial Plankton T”, or combination of all diets
reared in an intesive culture system .......................................................... 28

Figure 1.3—- Percent survival for ﬁrst-feeding yellow perch fry of Trial-3 fed
Anemia nauplii, vinegar eels, Artiﬁcial Plankton TM, or combination of all diets
reared in an intensive culture system ........................................................ 29

Figure 2.1--- Daily speciﬁc growth rate of male and female yellow perch (Perca
ﬂavescens) (141.5+-11.6 mm TL) reared in a recirculating aquaculture system
fed a commercial diet (Purina AquaMax 400) at 0.5, 1.0, 2.0, and 3.0% body
weight per day for 112 days. A=Females (r2=0.96), =Males (r2=0.88)..............65

Figure 2.2-—- Mean protein efﬁciencies (protein gained/dietary protein) of
predominately-male (PM) and all-female (AF) stocks of yellow perch (Perca
ﬂavescens) (141.5:11.6-mm TL) fed ration levels of 0.5, 1.0, 2.0, and 3.0% body—
wet weight per day for 112 days. Y-bars represent the standard error of the

mean ................................................................................................. 81

Figure 2.3-—- Mean lipid efﬁciencies (lipid gained/dietary lipid) of predominately-
male (PM) and all-female (AF) stocks of yellow perch (Perca ﬂavescens)
(141.5:11.6-mm TL) fed ration levels of 0.5, 1.0, 2.0, and 3.0% body-wet weight
per day for 112 days. Y-bars represent the standard error of the mean. . .82

Figure 2.4-"- Mean energy efﬁciencies (energy gained/dietary energy) of
predominately-male (PM) and all—female (AF) stocks of yellow perch (Perca
ﬂavescens) (141.5:11.6-mm TL) fed ration levels of 0.5, 1.0, 2.0, and 3.0% body-
wet weight per day for 112 days. Y-bars represent the standard error of the

mean ................................................................................................. 83

Figure 2.5-—- Mean feed efﬁciencies (weight gained/weight of feed fed) of
predominately-male (PM) and all-female (AF) stocks of yellow perch (Perca
ﬂavescens) (141.5:11.6-mm TL) fed ration levels of 0.5, 1.0, 2.0, and 3.0% body-
wet weight per day for 112 days. Y-bars represent the standard error of the

mean ................................................................................................. 85

Appendix A, 3.1- The recirculation aquaculture system used to rear yellow
perch (Perca ﬂavescens) for 112-day experimental period. Water was pumped

xii

from the bioﬁlter, rotating biological contact ﬁlter and Shredded, to the
experimental culture tanks. The water ﬂowed from the experimental culture tanks
into a gutter system that channels the water into a primary solids removal
system, screens. Small-suspended solids were passively removed in a large

settling tank. Water exited the passive solids removal tank and entered the
bioﬁlter ............................................................................................. 104

Appendix A. 4.1-- Water depth was determined by the height of the external
standpipe. A ball valve at the tanks lowest point aided in large solids removal by
allowing a small settling area above the valve. Opening the valve removed all
the accumulated solids ........................................................................ 105

xiii

INTRODUCTION

Yellow perch (Perca ﬂavescens) are a highly valued commercial food and
sport ﬁsh in the Great Lakes region. There has been a dramatic decline in wild
stocks since the early 1970’s that has not been reversed (Riepe 1998). Yellow
perch were commercially harvested from the Green Bay (Lake Michigan),
Saginaw Bay (Lake Huron), and western Lake Erie. Commercial landings in the
Great Lakes reached 16.3 million-kg/yr in 1969, but dropped to 4.7 million-kg/yr
in 1976 (Riepe 1998). Data from the Great Lakes Fishery Commission (2000)
reported that there was a 14% decline in commercial landings from 1977 to 1990.

The cause of the decline of wild stocks of yellow perch in the Great Lakes
is unknown. Researchers have speculated that several factors may have
contributed to this decline: introduction of competitive species such as zebra
mussel and alewifes, a signiﬁcant gender Shift to a predominantly female
population, water quality and habitat degradation, and increased ﬁshing
pressure. Fluctuations in the population may also have been a natural cyclic
event. The population decline lead to the Closure of the commercial yellow perch
ﬁshery in Lake Michigan waters in 1996 (David Clapp, Michigan Department of
Natural Resources, Charlevoix, Ml, personal communication, 1998). Currently,
Canadian waters of Lake Erie and Huron are the primary source of commercially
harvested yellow perch for the food ﬁsh market (Lesser and Vilstrup 1979). Tribal

commercial ﬁshermen continue to harvest yellow perch from Michigan waters.

Consumer demand has remained high for yellow perch ﬁllets (Lesser
1978, Lesser and Vilstrup 1979, Riepe 1998). Consumers value yellow perch as
a food ﬁsh because of their mild taste and ﬁrm ﬂesh (Lesser and Vilstrup 1978).
Recent price estimates reﬂect the elasticity of demand for yellow perch.
Wholesale prices for perch in the round have ranged from approximately $5.10 to
$6.60 per kg (Malison 1999). Wholesale prices for yellow perch ﬁllets have
ranged from $13 to $17 per kg (Riepe 1998). Retail prices for yellow perch ﬁllets
have reached $24 per kg (North Central Regional Aquaculture Center (NCRAC)
1996). High demand coupled with the decline in commercial harvest has made
yellow perch one of the most valuable potential aquaculture species in the
Midwest United States (Brown et al. 1996).

Several factors impede the development of a commercially viable,
intensive aquaculture industry for yellow perch in the North Central Region (Kelly
2000). In 1997, NCRAC formulated three research objectives to address some
of these impediments. This thesis addressed two of the objectives:

1. With the goal of larval intensive yellow perch feeding in tanks from the
onset of ﬁrst feeding, continue to develop methods to produce ﬁngerlings.
2. Increase growth rates of yellow perch greater than 150 mm (6") by
evaluating diets, feeding strategies, environmental manipulation, and
mono-sex/bi-sex comparisons.
Chapter 1 summarizes experiments designed to improve the survival of
yellow perch fry fed in tanks from the onset of ﬁrst feeding. Chapter 2

summarizes experiments designed to determine the bioenergetic responses of

10 to 17.5-cm male, female, and mixed gender populations of yellow perch using

a saturation kinetic model based on a multiple non-linear regression analysis.

HYPOTHESIS

The speciﬁc hypothesis tested for each objective in this study are:

Chapter 1 Objective 1
Null Hypothesis 1.1: Survival rates of ﬁrst feeding yellow perch will be equal
among fry fed vinegar eels, Artemia nauplii, artiﬁcial plankton, and their
combination.

Chapter 2 Objective 2
Null Hypothesis 2.1: The growth rates between male, female and mixed stocks
will be equal.
Null Hypothesis 2.2: The percent crude protein on a dry matter basis will be
equal between male, female and mixed stocks.
Null Hypothesis 2.3: The percent crude lipids on a dry matter basis will be equal
between male, female and mixed stocks.
Null Hypothesis 2.4: The percent energy on a dry matter basis will be equal
between male, female and mixed stocks.
Null Hypothesis 2.5: The percent moisture will be equal between male, female
and mixed stocks.
Null Hypothesis 2.6: The percent ash will be equal between male, female and

mixed stocks.

 

LITERATURE REVIEW

The market for yellow perch reﬂects strong consumer demand (Lesser
1978; Lesser and Vilstrup 1979). Riepe (1998) surveyed restaurants that sold
yellow perch and found 2/3 of the respondents were located within 50 miles of
the Great Lakes. She reported wholesale prices Of yellow perch ﬁllets ranged
from $13 to $17 per kg. The NCRAC reported perch retailing for $24 per kg
(1996). Wholesale for perch in the round changed from approximately $5.10 to
$6.60 per kg (Malison 1999). Because of the high demand and limited supply,
yellow perch is often replaced with an imported species (i.e. pike-perch,
Stizostendion Iucioperca). These species are often sold as “lake perch”, which
deceives the public. High demand coupled with the decline in recruitement has
made yellow perch one of the most valuable aquaculture species in the Midwest
United States (Brown et al. 1996).

The current market size of yellow perch is 115-150-g (Bennett Fish lnc.,
Loraine, OH, personal communication). Cultured yellow perch can reach market
size 2 years eadier than wild ﬁsh (Malison 1999). Under optimal conditions of
21°C with 16-h light and 8-h dark, yellow perch fed to satiation have reached a
marketable size in 9-11 months (Calbert and Huh 1976). Starr (1991) has shown
that yellow perch grown at 20 to 24°C grew 0.8 to 1.1-cm per month with feed
conversions (kg feed/kg weight gain) of 1.3 to 3.5. Wild yellow perch are able to

reach a market Size in 4 years (Carlander 1950).

Yellow perch reared under controlled culture conditions command a higher
price than wild caught ﬁsh (Chris Bennett, Lake Erie Aquaculture, Lorain, OH,
personal communication). Cultured yellow perch have a ﬁllet yield of 45%, 5%
greater than wild caught ﬁsh (Heidinger and Kayes 1993). Fillets from cultured
ﬁsh are generally more uniform in size (Lesser and Vilstrip 1979).

Yellow perch has been identiﬁed as a suitable candidate for aquaculture
within the North Central region. They are able to tolerate high loading and
densities, handling, and marginal water quality (Heidinger and Kayes 1986,
Glass 1991 ).

Methods for inducing early or delaying reproduction (Cieszko et al. 1997)
and inducing synchronous spawning (Malison et al. 1997) have been developed.
Yellow perch are seasonal spawners which require 160-d chill period
(temperature less than 10°C) for complete egg development (Hokanson 1977).
However, lack of well developed strategies for feeding fry from the onset of ﬁrst-
feeding result in a large variation in survival of fry (see Chapter 1).

Basic nutritional requirements for yellow perch have been determined and
practical feeds have been formulated for ﬁngerlings to market size ﬁsh (Brown et
al. 1996; Brown and Twibell 1997; Ramseyer and Garling 1994, 1998).
Ramseyer and Garling (1994) indicated that the protein requirements of yellow
perch are more similar to a channel catﬁsh than rainbow trout; but, aquaculturists
often feed trout diets to yellow perch.

The optimum environmental parameters for culturing yellow perch have

been reported. Since yellow perch are ectothermic, environmental temperature

inﬂuences metabolic reactions. Hokanson (1977) demonstrated that yellow perch
have a zero net biomass gain at temperatures below 6°C. His study also
determined that the Optimum physiological temperature is 25.1°C. Huh et al.
(1976) established that yellow perch grow best with 16-h Of light and 8-h of dark,
at a temperature of 20°C. However, other researchers have reported a wide
variation in optimal rearing temperature from 20-28°C (Heideinger and Kayes
1993; McCormick 1974, 1976). Some of the differences in reported optimum
rearing temperature might be the result of using different geographic stocks. It
has been found that the optimal rearing temperature is a function of geographic
region. Perch from northern and southern stocks grow better at lower and higher
temperatures, respectively. However, optimum growth temperature for all
geographic stocks was 20°C (NCRAC 1993).

The dissolved oxygen (DO) level for yellow perch should be maintained at
concentrations greater than 3.5-mg/L in ponds (Carlson et al. 1980) and the
efﬂuent of ﬂow through systems (Glass 1991). This is similar to the 3.0-mg/L
minimum DO requirement for channel catﬁsh (Carter and Allen 1976). Rainbow
trout require 5 to 6-mg/L D0 in the efﬂuent from raceways (Piper et al. 1982)

Three methods have been used to commercially rear yellow perch:
outdoor ponds, raceways, and indoors recirculating systems. All three methods
are employed in the North Central Region.

PONDS:
Yellow perch have been spawned in small ‘A hectare ponds. Fish were

stocked into the ponds and Often allowed to spawn on a substrate (i.e. small pine

 

tree). Eggs were removed from the substrate and incubated indoors. Shortly
after hatch, fry were returned to fertilized outdoor ponds. The fry are feed
trained and reared in these ponds until they reach a marketable size.

The advantage of rearing yellow perch in pond was the decreased labor
expense. The natural production of food generated within a pond will decrease
the feed conversion ratio.

The major disadvantages to raising ﬁsh in ponds are the amount of land
required, capital cost of building ponds, adequate sources of water, and seasonal
changes in temperature and photoperiod.

Pond culture requires a signiﬁcant investment in land. Riepe (1997)
estimated that 20 acres of ponds are required to raise 50,000-lbs/yr (22,675
kg/yr) in central Indiana. She determined that the initial investments cost for
5,000-lb production system were $39,182, and $140,238 for a 50,000-lb
production system. The total annual costs are $17,416 for the 5,000-lb facility
and $107,079 for the production of 50,000-lbs. The breakeven price (total cost
per pound) was $2.14/lb for the 50,000-lb production facility. However, the
5,000—lb breakeven price is $1.34 greater. Wholesale prices ranged from $2.00
to $3.00 per pound. There is a limited proﬁt margin.

Perhaps, the major disadvantage to rearing yellow perch in ponds was the
variable climatic conditions and photoperiod in the NCR. The length of time
required to grow perch to a market size of 115-150-g or 20-cm TL (Bennett Fish
lnc., Loraine, OH) in 8 months when starting with ﬁsh of approximately 110-mm

TL under natural conditions (Starr 1999, interpersonal communication).

Hokanson (1977) found that yellow perch gained no noticeable weight if
temperatures were maintained below 6°C. Pond water temperatures in Michigan
remain below 6°C for nearly 6 months. Yellow perch also grow best with 16
hours of light (Calbert and Huh 1976). The photoperiod in the upper Midwest is
highly variable. Fish use photoperiod as a cue for hormonal changes and
preparation for spawning.

Outdoor ponds may be important to establish broodstock and rear larval
ﬁshes (see Chapter 1). Yellow perch reach sexual maturity at 90-120-mm TL
(Schott 1980). Reports on perch and other species have shown a correlation
between sexual maturation and growth reduction, food consumption, and feed
efﬁciency (Huh 1975, Purdom 1976, Utter etal. 1983, Malison 1985).
RACEWAYS:

Yellow perch have been reared in raceways at Bayport Aquaculture, West
Olive, Ml. Raceway culture enables greater stocking density (kg/l) and loading
(kg/lpm) than pond systems. Glass (1991) determined that the maximum
loading for yellow perch for commercial raceway production was 0.85 to 1.15-
kg/Ipm (7.06 to 9.58-lbs/gpm). Fingerlings were reared up to a density of 85-
kg/m3 (0.71-le/gallon) without reductions in growth, survival, or performance.
This is considerably greater than maximum densities recommended (50-kglm3,
0.42-le/gallon) for salmonids (Piper 1982).

The primary disadvantage of raceway culture is that the number of
appropriate sites able to supply high volumes of water at the appropriate

temperature are limited (Glass 1991). Additionally, efﬂuent restrictions on

receiving waters may exclude potential sites with high volumes of water at the
appropriate temperature (Gary Boersen, Michigan Department of Environmental
Quality, Lansing, MI, personal communication, 1999)

RECIRCULATING SYSTEMS:

Recirculating aquaculture systems (RAS) are comprised of culture tanks,
bioﬁltration systems, solids removal systems, and sterilizers (Lucchetti and Gray
1988). The RAS are designed to provide optimum rearing conditions while
minimizing the impact on natural environments. Large areas of land are not
needed to house a RAS. Large quantities of ﬁsh can be reared within a single
tank under adequate conditions. Calbert and Huh (1976) estimated that a 1-1.5-
9 yellow perch, reared under Optimal conditions, could reach a market weight of
140-160-g in 11 months when fed 4% of their body weight per day. Because of
these perceived potential advantages, many potential yellow perch producers
have opted to use indoor RAS (Kelly 2000).

Timmons (2000a, b, C) has identiﬁed various reasons aquculturists have
failed in their attempts to establish proﬁtable RAS. An in-depth cost analysis was
listed as an important requirement for new aquaculture enterprises; however,
many cost analyses of RAS have been superﬁcial. The ﬁrst general falsehood
described by Timmons (2000) was that a current unsuccessful dairy or hog
farmer can become a successful ﬁsh farmer. Expert and experienced
management was identiﬁed as a critical component for the success of a

recirculating aquaculture system.

10

Kelly (2000) speciﬁcally summarizes characteristics that currently impede
the development of commercial yellow perch aquaculture. However, Manci
(2000) rebuts many of her assertions by stating current research is focused on
advancing the technologies of culturing yellow perch, therefore making yellow
perch culture more proﬁtable.

US PRODUCTION OF YELLOW PERCH

Malison (1999) has estimated that yellow perch aquaculture contributed
less than 100,000-kg per year to the commercial food market. He reported that
existing markets could readily absorb 23-45 million-kg per year. Cost effective
culture methods must be developed before aquaculturists can take advantage of

the potential food ﬁsh market.

11

CHAPTER 1
EVALUATION OF FEEDING STRATEGIES
FOR FIRST-FEEDING YELLOW PERCH FRY
Introduction

The growth of commercial yellow perch aquaculture in the Great Lakes
region is dependent on the development of reliable, cost-effective, culture
methods. Methods are needed for each life cycle stage: eggs, ﬁrst feeding fry,
ﬁngerling through market-sized ﬁshes, and broodstock (including out of season
spawning).

Currently, the most commonly used brood ﬁsh are captured, sexually
mature wild yellow perch. Eggs are manually stripped and fertilized using the dry
method (summarized in Piper 1982). Yellow perch eggs are deposited as single
interconnected, gelatinous ribbon-like mass. A 25-Cm total length (TL) female
yellow perch can produce up to 30,000 eggs (Malison 2000). The fertilized egg
ribbons are incubated in tanks (Malison 2000) or vertical drip incubators (Oekter
1999). The ribbon is stretched over a wire grate within the tank or around pegs
placed in the vertical incubator tray to prevent bunching which can smother
individual eggs. Water is passed over the egg ribbons.

Once the eggs hatch and the fry are free swimming, they are most often
moved to fertilized outdoor ponds. Commercial grow-out of yellow perch ﬁrst
feeding fry (YPF FF ) to ﬁngertings currently relies on intensive pond production
methods (Malison and Held 1995). Ponds are drained prior to stocking to

remove all remaining ﬁsh from the previous year. An organic fertilizer is applied

12

 

to promote plankton production and the ponds are reﬁlled. The sac-fry are then
transferred from the incubation units to the fertilized pond. The fry consume
plankton upon exogenous feeding.

Yellow perch fry are feed trained to formulated feeds once the fry reach 15
— 20-mm TL (Hale and Carlson 1972; Malison 2000). Feed training is changing
the diet of the yellow perch fry from a natural diet to a formulated diet. Current
methods used to feed train yellow perch fry in ponds employ light to attract the fry
to a feeding area (Manci et al. 1983). After a short time delay, feed is dropped
into the pond under the light platform. Another method used to feed train fry
(called the tandem pond-tank method) relies on harvesting the fry from the pond
and moving them into tanks to begin feed training (Malison 2000).

The primary advantage to intensive pond production of yellow perch
ﬁngerlings is large numbers of ﬁsh can be successfully produced. However,
environmental parameters such as temperature, dissolved oxygen, total
ammonia, and zooplankton abundance must be consistently monitored.
Precipitous changes in any of these parameters can adversely affect the growth
and survival of yellow perch fry. Since the aquaculturist has minimal control over
these parameters, the entire stock can be lost.

If intensive tank rearing systems can be developed to culture YPFFF,
environmental conditions can be controlled to optimize growth and survival of
rearing yellow perch larvae to 20-mrn. However, high mortality rates ranging from
70 to 100% have occurred when larvae change from their endogenous food

source (yolk) to exogenous sources (practical feeds). NCRAC has identiﬁed the

13

following constraints as major causes of the high mortality rates observed in
intensive yellow perch larval tank culture systems:

a. Lack of swim bladder inﬂation.

b. Lack of acceptance of a practical feed at ﬁrst feeding.

A beneﬁt to controlled tank rearing of yellow perch fry is the potential for
out-of-season spawning. Researchers are currently establishing protocols for
spawning yellow perch out of their normal spawning period (NCRAC 1997) by
manipulating photoperiod, temperature, and hormone levels. Out-Of-season
spawning would enable producers to rear multiple crops per year.

This study was designed to evaluate potential ﬁrst feeds for the intensive
culture of yellow perch that are economically feasible. The culture system was
designed to facilitate swim bladder inﬂation (Barrows 1993). Survival rates of
YPFFF fed live Artemia nauplii, live vinegar eels, Artiﬁcial PlanktonTM (a practical
larval shrimp diet) produced and marketed by Argent Chemical Laboratories
(Redmond, WA), and combinations of three diets were monitored. The live feed
items were chosen because they were within the Size range of organisms that
can be consumed by YPFFF (Oekter 1998), their relative ease of culture, and
their established use in aquaculture and the aquarium trade, respectively.
Vinegar eels are also very inexpensive to produce. Artiﬁcial plankton was also
inexpensive, of an appropriate size, had a high-energy content, and a high level

of essential fatty acids.

14

Literature Review

Both pond and tank rearing techniques have been utilized to produce
yellow perch larvae. Intensive tank rearing technologies have been inadequate
and fail to meet the commercial demands for yellow perch ﬁngerlings.

Commercial yellow perch facilities have reared larval yellow perch in
ponds that are fertilized with an organic fertilizer prior to stocking (Manci et al.
1983; Malison and Held 1992). The fertilized ponds provide a natural food
source for the fry. Under highly controlled and monitored conditions, production
levels of over 570,000 yellow perch fry (25-mm TL) per hectare (1 ,400,000/acre)
have been reported (Manci et. al. 1983; Malison and Held 1992). However,
under typical commercial conditions, actual numbers of fry produced have been
under 40,000/ha (100,000/acre). Year-to year environmental ﬂuctuations have
resulted in large variations in survival. These variations in survival rates could
have been caused by changes in the abundance and size distribution of natural
food sources (Malison and Held 1995) or stress related to handling during
harvesting (Hussain and Summerfelt1991).

Feed training yellow perch fry in ponds has been moderately successful.
Feed was presented to the ﬁsh several times per day. Lights have been
incorporated to enhance feed training within ponds (Manci et al. 1983). This
modiﬁcation relies on the strong photopositive behavior of yellow perch larvae
smaller than 20-mm TL.

Many producers have used the tandem pond-tank rearing method. Once

yellow perch fry reach 15 - 20—mm TL, they are moved to indoor tanks to begin

15

feed training (Malison 1999). Once indoors, the ﬁsh would be trained on a
commercial starter diet. Culture conditions were monitored and yellow perch fry
were consolidated to ensure feed acceptance (Dr. J. Malison, University of
Wisconsin, personal communication, 1998). An inverse relationship between fry
survival and the length of the fry when formulated feeds are offered (Best 1981 ).
Survival rates have been described as high as 90% from this stage until grow
out. However, survival falls to below 50% if the ﬁsh is feed trained prior to 16-
mm TL (Hale and Carlson 1972).

The principal advantages in tank culturing larval yellow perch are
environmental and nutritional variables could be manipulated for maximum
growth and survival (Calbert and Huh 1976, Hale and Carlson 1972, Hinshaw
1985). This would be vital for out-Of-season spawning of yellow perch
(Dabrowski 1998).

Despite advancements in tank culture of yellow perch fry, two factors limit
success. YPF F F are inherently small which limits the size of feeds that can be
used (Best 1981; Mansueti 1964; Nickum 1978). A large number of yellow perch
have failed to inﬂate their swim bladder when reared in intensive culture systems.

YPFFF have been reported to range from 4.7 to 7.0mm TL (Heidinger
and Kayes 1986; Mansueti 1964; Ney 1978; Whiteside et al. 1985). YPFFF have
also been observed to have small mouth gapes which limits the size of prey they
can consume (Hansen and Wahl 1981; Wong 1972). Oekter (1998) reported that
the yellow perch mouth gape was 318 x 332 um (Oekter, 1998). Cunha and

Planes (1999) estimated the optimal size of prey for turbot larvae was 40%

16

mouth width and 36% mouth height. The size of the esophagus may also limit
the size of prey consumed (Kestemont et al. 1996; Raisanen and Applegate
1983). Busch (1996) reported a 1:1 ratio in prey width and esophagus diameter
in Clupea harengus. Consequently, the size prey consumed by YPFFF may be

signiﬁcantly smaller than 318-um.

Historically, tank reared yellow perch fry were feed zooplankton and
phytoplankton that were captured or cultured (Ansari and Quadi 1989; Confer
and Lake 1987; Hale and Carlson 1972; NCRAC 1995; Noble 1973; Raisanen
and Applegate 1983). Zooplankton population structure and size varies during a
growing season and between years due to different environmental conditions
(Houde 1967; Mills et al. 1986). Reports of failures using zooplankton to rear
YPFFF may have resulted from these factors.

The collection of zooplankton from rivers and lakes for feeding larval ﬁsh
has been found to be an unreliable source of food for commercial scale
operations (Kamler 1992). Therefore, some researchers have focused on
culturing zooplankton. Live feed production has been successful in Japan
(Kalmer 1992). However, phytoplankton and zooplankton cultures required large
amounts of space and skilled labor.

A “green tank water" method (GW) for culturing multiple zooplankton
species has been developed (Binkowski, see review in NCRAC 1995). The CW
is added to the culture tank as a food for ﬁrst feeding perch. This method

appears to have had limited acceptance by commercial producers. Many

17

commercial producers ﬁnd it difﬁcult to obtain the proper zooplankton species
composition and abundance to maintain the fry.

Larval ﬁsh growth and survival depend on the chemical properties of the
diet (Watanabe et al. 1983). The National Research Council (1993) reported
docosahexaenoic acid (DHA, 22:6 omega 3), eicoapentaenoic acid (EPA, 20:5
omega 3), and linolenic acid (18:0mega 3) are essential fatty acids for several
species of ﬁsh. Tissue levels of DHA and EPA were higher in young perch than
in the majority of their prey items (Dabrowski et al. 1993). Zooplankton caloric
contents are different between species and within a species, seasonally
(Schindler et al. 1971 ). A single species Of zooplankton may not be capable of
supplying the long-chain fatty acids or energy required for survival and growth of
larval ﬁsh.

There are alternatives to zooplankton. Newly hatched Artemia nauplii
could be of the appropriate size for YPFFF (Oekter 1998). There has been some
success in feeding Artemia nauplii to YPF F F (Hinshaw 1985; Mansueti 1964;
McCormick 1976). European perch had a survival rate of 85% at day 14 when
fed Artemia nauplii (Valvonou et al. 1995). Artemia has been used to
successfully rear mahimahi and moi, both similar in size to yellow perch, at the
Oceanic Institute (Kim et al.1993). Another possible alternative to zooplankton is
vinegar eels. Vinegar eels have been used to successfully rear larval ﬁsh (Chen
1981). Vinegar eels may also provide a valuable food source at a lower cost.

Several researchers have been exploring the use of formulated diets as

the initial food for ﬁrst feeding fry (NCRAC 1997). Minimum pellet size exceeds

18

minimum mouth gape; but, microencapsulated feeds are in the size range that
can be accepted by YPF FF. Microencapsulated feeds have been used to
successfully rear Dover sole and sea bass larvae (Appelbaum 1985; Walford et
al. 1991). Best (1981) reported that YPF FF did not accept or survive on a
formulated diet. Researchers have developed a formulated diet for walleye FF F
(Barrows et al. 1988).

Physical properties of the feed and the culture system may contribute to
feed acceptability, survival, and growth. Ostrowski (1989) found that dolphin
larvae reared on a brown feed in black tanks had a greater survival rate than ﬁsh
reared on the same feed in tan tanks. Martin-Robichaud and Peterson (1998)
determined that swim bladder inﬂation was greater in black tanks compared to
white tanks. There were no signiﬁcant differences in growth of Atlantic salmon
parr reared in green or gray tanks (Stefansson and Hansen 1989). Therefore, a
culture system of a contrasting color to the feed improved feed acceptance.

Many culturists have believed that the lack of swim bladder inﬂation has
been the main cause of the high mortality of intensively reared YPFFF (C. Starr
interpersonal communication 1999). Larval yellow perch ﬁll their swim bladder by
swimming to the surface and gulping air. Swim bladder inﬂation can occur in 11
days at 8°C or less than 2 days at temperatures greater than 15°C (Hokanson
1977). Swim bladder inﬂation problems have also been reported for walleye
(Barrows et al. 1988) and stripped bass (Doroshov and Comacchia 1979). These
species appear to required an unobstructed path to the surface to inﬂate the

swim bladder. Colesante et al. (1986) found that swim bladder inﬂation rate of

19

walleye was greater in tanks where ﬁsh were fed live feeds when compared to
ﬁsh fed a formulated feed. Formulated feeds may have caused a surface ﬁlm on
the water. Barrows et al. (1993) reported that a vertical spray at 90° to the water
surface would break up the surface ﬁlm and allow the larvae to ﬁll their swim
bladder.

Tank culture technologies must be developed in order to provide a
continuous supply of yellow perch to meet commercial food production needs.
These techniques will enable commercial producers to rear yellow perch larvae

year round when out-of-season spawning techniques are deveIOped.

20

Materials and Methods
This study was designed to evaluate the potential of Artemia nauplii,
vinegar eels, Artiﬁcial Plankton (Argent), or the combination of all three as a feed
for YPFFF. YPFFF survival rates were determined and compared between the
diets. Four intensive larval rearing trials were performed. Each successive trial
was a modiﬁcation of the previous trial. All trials were performed at the Michigan

State University Aquaculture Research Laboratory.

Intensive Larval Culture: Trial 1

Fish and Holding Tank

Yellow perch sac-fry (fry dependent on endogenous yolk food supply)
were obtained from Bay Port Aquaculture in West Olive, Michigan in April 1998.
The fry were originally acquired by Bay Port Aquaculture from a commercial
grower in Iowa. Sac-fry were held in a 230-L green ﬁberglass tank for a two-day
acclimation period. Heated well water (15°C :I:1) was provided at an exchange
rate of 0.5 turnovers per hour. The drain of the tank was covered with 300-um
Nitex screening to prevent fry escapement. The photoperiod was maintained at
16-h light and 8-h dark.
Experimental System

Twelve green 5-gallon pales were used to create experimental larval
rearing tanks. A tubular center screen was constructed with using a 2" PVC pipe

with portions removed. The openings were covered with 150-pm Nitex screen to

prevent YPFFF escapement (Figure 1.1). Heated well water (15°C 11) was

21

 

 

 

Figure 1.1-— Center drain tube made of 2-inch PVC pipe with the Sides cutout
and holes covered with 300-um Nitex screening.

22

sprayed over the surface at a rate of 0.25-L/min using a system similar to the
design described by Barrows et al. (1993). Water levels were maintained in each
tank with an external standpipe. Each tank was randomly stocked with 100
YPFFF. The photoperiod was maintained at 16-h light and 8—h dark.
Feeds and Feeding

Four replicate tanks, each, of fry were fed one of three diets: ﬁrst hatch
Artemia nauplii, Artiﬁcial PlanktonTM (both obtained from Argent, Redmond, WA)
or vinegar eels. Culture methods for Artemia nauplii and vinegar eels are
described in Appendix 1 and 2, respectively. Fry were fed 5 times per day at
0800, 1100, 1300 1500, and 1800. Artemia was fed at a rate of 15,000
nauplii/tank/feeding. Artiﬁcial Plankton was fed at a rate of 1-g/feeding/tank.
Vinegar eels were fed at an approximate rate of 15,000 eels/tank/feeding.
Survival and Swim Bladder Inﬂation

Survival was determined by comparing the number of live ﬁsh 28 days
after stocking the experimental tanks. Fish were expected to reach 15 — 20-mm
under our conditions by the end of the period (Hokanson 1977). Live ﬁsh were
removed from each tank and observed under 10-power magniﬁcation for swim
bladder inﬂation and feed consumption. Moribund and dead fry were collected
daily and examined under a dissecting microscope to determine swim bladder

inﬂation rates.

23

lntenslve Larval Culture: Trial 2
Eggs and Incubation

Gravid female and milt producing male yellow perch were collected in May
1998 from southern Lake Michigan, offshore of St. Joseph, Michigan. The
parental stock was transported on the day of capture to the Michigan State
University Aquaculture Research Laboratory. Eggs were stripped from ripe
females into a small dry pale. Milt was collected from males and was directly
added to the ripe eggs. Water was added to “activate” the fertilization process.
Two minutes after water activation, a gentle ﬂow of fresh water was added to the
container for 1 hour to water harden the eggs.

After water hardening, eggs were incubated in a 230-L oval green tank
supplied with 15°C :1 well water. Ribbons were laid out on a screen mat placed
4 inches off the bottom of the tank. Water was supplied to the bottom of the tank
to create an upwelling ﬂow. Eggs were incubated for 7 - 11 days. Two days after
hatching, ﬁsh were stocked into experimental larval rearing units and reared as

described in Trial 1.

Intensive Larval Culture: Trial 3

Eggs and Incubation

Freshly spawned eggs were obtained from Bay Port Aquaculture in April
1999. The eggs were transported to the Michigan State University Aquaculture
Research Laboratory. The fertilized eggs were incubated in a Heath vertical

incubator supplied with 13°C well water at a rate of approximately 2.5-me (0.66

24

gpm). After fry hatched, they were conveyed to a 378-L (100 gallon) holding
tank. The holding tank dimensions were 122 X 122 x 25.4-cm (48 X 48 X 10-in).
The holding tank was supplied with efﬂuent water from the incubation unit. The
incubation unit water was added at the surface of the holding tank to create a
counter—clockwise vortex to aid in tank cleaning. The incubation and holding

system was maintained under constant light.

Experimental System and Culture

One hundred 1-d post-hatch sac-fry per tank were randomly stocked into
12 square 40-L gray tanks. All tanks were equipped with 2.54-cm (1-inch)
internal drain tubes similar to those described above. Drain tubes were covered
with 150 um Nitex screening to prevent fry escape. Well water was supplied
using the same method described in Trial 1. Water temperatures were
maintained at 13°C. Photoperiod was maintained at 16-h light and 8-h dark.

Fish reared in the experimental tanks were fed as described in Trail 1.
Fish remaining in the holding tank were fed a combination of all three diets 5

times per day.

Intensive Larval Culture: Trial 4
Fish and System
Approximately 60,000 fry, 1-d post-hatch, were obtained from Bay Port
Aquaculture. The ﬁsh were transported to Michigan State University’s Upper

River Research Laboratory. Fish were held in a 122 X 122 x 25.4-Cm (48 X 48 X

25

 

10-in) holding tank at 125°C for the duration of the experiment. Well water
pumped into a head tank and aeration was supplied to ensure optimum oxygen
levels. The water was dropped at near 90° to the surface into the holding tank to
create a counter-clockwise vortex to help in keeping the tank clean. The system
was maintained under constant light.

YPF F F were fed ﬁve times per day beginning one day after stocking.
Newly hatched Artemia were initially fed at a rate of 75,000 per feeding.
However, Artemia was not used after day-3 because of a very poor hatch rate.
Artiﬁcial Plankton was fed at a rate of 3-g per feeding. Vinegar eels were fed at
an approximate rate of 200,000 eels per feeding.

Solid wastes were siphoned from the tank each morning after the ﬁrst
feeding. Five ﬁsh were removed each day to determine the rate of swim bladder
inﬂation. Each larva was examined under a dissecting microscope under 10-

power magniﬁcation to determine swim bladder inﬂation and stomach contents.

26

Results

In trial 1, feeds were not presented until the Oil globule was the only
remaining endogenous food source. Experimental tanks were stocked with 100
fry per tank. Feedstuffs were offered immediately after stocking. Total mortality,
on day-8 post-stocking, occurred in all tanks (Figure 1.2), including the holding
tank. Trial 2 followed a similar pattern. Total mortality occurred within 8-9 days
post stocking.

During trial 3, a total of 3 fry per day were removed from the experimental
systems and observed under 10-power magniﬁcation to determine swim bladder
inﬂation and stomach contents. By day-8, all fry observed had consumed the
feeds. Identiﬁcation of the feed was determined by the color in the digestive tract
of the fry. Orange indicated Artemia and yellow indicated the Artiﬁcial Plankton
T” had been consumed. Vinegar eel body parts were identiﬁed within the
digestive tract Of the YPFFF while the fry were observed under 10X
magniﬁcation. Swim bladder inﬂation was not observed in any of the ﬁsh
sampled from the experimental system. No ﬁsh survived in the experimental
tanks past day 11 after stocking in trial-3 (Figure 1.3).

During trial 3, ﬁsh from the holding tank were sampled to identify swim
bladder inﬂation and feed consumed. Fish had readily consumed all diets by
day-8. Swim bladder inﬂation occurred between day 7 and day 12. Greater than
75% survival was observed through 28 days post-hatch. However, due to
increased fungal build up on solids that collected over the efﬂuent screen, the

tank overﬂowed and ﬁsh were lost overnight.

27

 

100

g 80 1 __._Combrnatron
iii 60 i _._Artemia
E 40 .
§ 20 +Vinegar Eels
O)
n. 0 .

o 12 .. .Artiﬁcial

Plankton

 

 

 

 

Figure 1.2 «- Percent survival for ﬁrst-feeding yellow perch fry of Trial-1 fed
Artemia nauplii, vinegar eels, Artiﬁcial Plankton T”, or combination of all diets
reared in an intesive culture system.

28

 

Percent Survival

 

+A‘liﬁdd Plankton

Figure 1.3-- Percent survival for ﬁrst-feeding yellow perch fry of Trial-3 fed
Artemia nauplii, vinegar eels, Artiﬁcial Plankton W, or combination of all diets

reared in an intensive culture system.

29

Trial 4 replicated the conditions used in the holding tank during Trial 3.
Fish were examined for swim bladder inﬂation and feed consumption daily. Fish
survived for 8 days. Mass mortalities were observed on the morning on day 9.

No swim bladder inﬂation or feed consumption was observed.

30

Discussion

This study was designed to compare the survival and growth rates of ﬁrst-
feeding yellow perch fry using two different live feeds and one artiﬁcial feed.
Survival rates observed during this study were considerably lower than
previously reported (Hinshaw 1985). This could have been due to several
factors:

1. Poor water quality

2. Handling stress

3. Improper nutrition

A. Larval

B. Parental
l. Genetics
ll. Egg quality

4. Lack of swim bladder inﬂation

The inherent small size (approximately 7-9-mm) of ﬁrst feeding yellow
perch fry poses another problem. A 150-um Nitex screening was used over an
internal standpipe. The addition of the feeds to the system appeared to inhibit
the efﬂuent ﬂow. Increased organic retention may have caused the fungal build
up within the tanks. Tanks fed Artiﬁcial PlanktonTM exhibited the greatest amount
of fungal build up. The low efﬂuent ﬂow coupled with the high fungal content
contributed to lowering the water quality.

The majority of observed mortalities occurred prior to day-7. Typically,

high mortality occurring within 7 days has been attributed to stress. Handling

31

stress has been identiﬁed as a major factor affecting larval yellow perch survival
(Malison 2000). No acclimation period was used because of the early stage at
which yellow perch fry change from endogenous to exogenous food sources.

Large amounts of fungus on the efﬂuent screens made tank cleaning and
maintenance difﬁcult. The increased time siphoning the tank would have
contributed to an increase in stress among the fry. The combination of increased
stress levels from initial stocking, tank maintenance, and declined water quality
may have increased mortality rates above those previously reported.

Temperature affects yolk utilization in larvae (Ware 1975). Newly hatched
yellow perch fry use their yolk sac as their primary source of nutrients for 5-7
days post hatch at temperatures of 125°C (Hokanson 1977). Therefore, feed
was presented to the yellow perch fry immediately after stocking.

Fish were observed feeding directly after feed was presented. This
implies that yellow perch begin feeding shortly after hatch. Siefert (1972) had
observed that larval perch accepted feed prior to complete yolk absorption. Our
study did not determine whether the feed was assimilated. Dabrowski (1997)
reported that yellow perch fry have incomplete digestive systems while the oil
globule was still present.

Larval ﬁsh have a higher energy requirement then adult ﬁsh. Therefore,
feed must be present within the system at all times. Research has shown fry
mortality rates of 100% occur if feed is not present for 12 hours (Jonas and Wahl
1998). It was observed in our study that Artemia settle from the water column

within a hour, where as vinegar eels and Artiﬁcial Plankton T" remained in the

32

 

water column for several hours. In our experimental trials, fry were feed 5 times

daily over a 12-h period for culturist convenience. Therefore it can be concluded
that in experimental tanks that were fed Artemia may not have had feed present

for 11 hours, which may attribute to the high mortality rates. Tanks that were fed
vinegar eels or Artiﬁcial PlanktonTM may have been nutritionally deﬁcient.

The yellow perch fry used in this study were offspring of wild caught yellow
perch from Lake Huron or Lake Michigan. The nutrition histories of the parents
were not monitored. The culturist has no ability to control the nutrition provided
to maternal parents to ensure appropriate yolk development. Therefore, the
nutritional quality of the yolk could have affected fry survival. The yolk may have
been energy deﬁcient.

The nutritional history of the parental stock has been shown to inﬂuence
the survival rates of their offspring. Thiamin deﬁciency has been identiﬁed as a
possible cause of early mortality syndrome in many salmonids from the Great
Lakes Region (Brown et al. 1998). In our study and Oekter (1998), yellow perch
fry exhibited short vertical swimming bursts followed by a rest period on the tank
bottom. This erratic swimming behavior was Similar to behavior exhibited by
salmonids with thiamine deﬁciency. Another sign, the failure to inﬂate the swim
bladder, was observed in thiamine deﬁcient salmonid fry and yellow perch fry.
Washing the eggs in a thiamine bath or injecting thiamine directly into the gravid
female's body cavity alleviated these symptoms (Brown et al. 1998).

The most probable cause of high mortality among the yellow perch fry in

our study was the lack of swim bladder inﬂation. The fry in our study were

33

observed swimming in vertical bursts of up to 4-inches, followed by a rest period
on the tank bottom, it is probable that the yellow perch fry expended the energy
reserves of their yolk for maintaining buoyancy, rather than development.
Hokanson (1977) demonstrated that at high temperatures the swim bladder was
inﬂated at an earlier stage. Swim bladder inﬂation can occur within 2 days post
hatch at 15°C (Hokanson 1977). Temperatures ranged from 13°C (trial 3 and 4)
to 15°C (trial 1 and 2), which is bordering the limit of optimal development.
Consequently, factors other than temperature probably caused the larval
mortality observed in the majority of our experiments.

A survival rate greater than 75% was observed for perch fry from the
holding tank for trial-3, until day-28. The holding tank had a larger surface area
and was shallower than the research tanks. The increased surface area to depth
ratio (820) may increased the chance of the fry ﬁlling their swim bladder by
allowing the ﬁsh to reach the surface with less effort. The increased surface area
could have inhibited the accumulation of surface debris, which would allow the fry
an increased probability of an unobstructed gulp of air. The holding tank was
maintained under constant light, which may have altered the biorhythm of the try.
Yellow perch fry are found to feed at night (Faurot and White 1994). The lack of a
photocycle may have increased the chance of the fry to feed while the feed was
presented. Also, a combination of Artemia nauplii, vinegar eels, and Artiﬁcial
Plankton T" were fed to the holding tank. A single feed may not meet the

nutritional requirements of the yellow perch fry.

34

Trial-4 was a replication of the holding tank system used in trial-3, one
year later. Total mortality occurred during trial-4. The mortality was attributed to
feed. Artemia was excluded from the feed because of very low hatch rates
(<10%). The previous years Artiﬁcial PlanktonTM was used because of limited
funding. Nutritional degradation may have affected the quality of the Artiﬁcial
Plankton“. Therefore, trial-4 fry were feed a diet that consisted of vinegar eels,
and expired Artiﬁcial Plankton TM.

Development of cultured brood ﬁsh is vital for the expansion of yellow
perch aquaculture. The availability of cultured brood ﬁsh would enable
researchers to develop diets that would ensure the nutritional quality of the yolk
which could decrease the variability in larval ﬁsh survival rates. If wild brood ﬁsh
are used as parental stock, research should be done to determine if thiamine
injections can increase the percentage of larval ﬁsh with inﬂated gas bladders.

Another possible area of interest for future research is the effect of surface
area to depth ratio on larval yellow perch survival. The increased surface area to
depth ratio could have had a positive affect on the survival of the fry. The large
surface area may have reduced the surface tension created by the meniscus at
the top of the tank and may have decreased the amount of surface ﬁlm from
decomposing and uneaten feeds. The decreased depth may have also

enhanced the ability of the fry to reach the surface to ﬁll their swim bladder.

35

Summary and Conclusion

The culture of yellow perch larvae has been identiﬁed as a research focus
for the North Central Aquaculture Center. This study was designed to compare
potential feeds for ﬁrst feeding yellow perch fry. Fry were either purchased from
a local commercial yellow perch producer or where hatched from fertilized egg
ribbons of wild caught yellow perch females.

Diets used in this study were Artemia nauplii, vinegar eels, and Artiﬁcial
Plankton“. Fry appeared to consume all diets when the diet was presented
directly after hatch. A high percentage of swim bladder inﬂation was achieved by
increasing the surface area to volume ratio in the holding tank. However, this
result was not duplicated in experimental tanks. In all experimental trials,
mortality rates of 100% were observed. Factors that affected mortality rates may
have been:

0 Handling stress

Poor water quality
- Improper nutrition or feed availability

Lack of swim bladder inﬂation

Improper parental nutrition

Handling stress can be minimized by not moving ﬁsh from tank to tank.
The small sizes of the fry increase their susceptibility to thermal stresses. Water
quality could be maintained if Artiﬁcial Plankton” had not been used. However,

water quality was not an issue in tanks fed Artemia nauplii or Vinegar eels.

36

Improper nutrition and lack of swim bladder inﬂation are two areas, which
require further research. The development of brood stock is vital to the

development of proper larval yellow perch nutrition.

37

Chapter 2
GENDER EFFECTS ON BIOENERGETIC RESPONSES
OF YELLOW PERCH FINGERLINGS
Introduction

Various researchers (Malison and Garcia-Abiado 1996; Malison et al.
1985, 1986; Schott et al. 1978) have reported that under intensive culture
conditions, yellow perch females grow faster than males after achieving a total
length (TL) of 110—mm. Determination of the bioenergetic responses of male,
female, and mixed gender populations of yellow perch may help commercial
farmers develop culture strategies to avoid gender based growth differences.

A kinetic saturation level model (Mercer 1980, 1992; Mercer et al. 1989,
1993, 1996) has been used to determine the basal metabolic energy
requirement, efﬁciency of diet utilization, and the theoretical maximum response
to feeds of mixed gender populations of Tilapia zillii by Annett (1985) and Nile
Tilapia, Oreochromis nilotica, Belal et al. (1991). This study was designed to
determine the effects of gender on the bioenergetic response of yellow perch
greater than 110-mm using a saturation level kinetic model. The general model

(Morgan et al. 1975) can be deﬁned by the equation:

 

b(Km)" + Rmaxﬂ]n
r - (K...)" + 0]"
Where:
r = Physiological observed responses.
b = Intercept on the ordinate y-axis.

38

Km = Intake constant for V2 of Rmax,

Rmax = Maximum response,

n = Slope factor (compared to Km, apparent kinetic order of the response
with respect to l as In becomes negligible),

l = Nutrient intake.

The model was used to calculate the theoretical maintenance level and
the maximum and optimal efﬁciency values for single and mixed gender stocks.
Values were determined based on growth (wet weight) and changes in proximate
analysis (protein, crude lipids, gross energy, moisture, and ash on a dry matter
basis) of whole body tissues. The values generated were used to determine if
reported differences in growth of male and female stocks have been caused by
differences in maintenance requirements or in the efﬁciency of feed utilization.

A collateral objective of this project was to identify yellow perch gender by
a reliable secondary sex characteristic. The identiﬁcation of an external
secondary sex characteristic would enable researchers to determine sex effects
as a factor in future research studies, as well as allowing commercial yellow
perch producers to evaluate single gender culture in practical culture operation

levels.

39

Literature Review

Gender Identiﬁcation

Female yellow perch begin to grow faster than male yellow perch after
reaching a size of 110-mm TL and, ultimately, reach a larger TL (Schott et al.
1978; Malison et al. 1985, 1986; Malison and Garcia-Abiado 1996). Wild yellow
perch reach this length within the second year of life. Yellow perch also develop
gametes during their second year of life. Gonad development often inﬂuences
the growth rates of ﬁsh including yellow perch (Hayes and Taylor 1990).

Yellow perch have an annual reproductive cycle. The development of
yellow perch gonads is dependent on temperature and photoperiod. Kayes and
Calbert (1979) determined that temperature has a more important role in gonad
development than photoperiod. Yellow perch require a minimum “chill” period of
160 days at 10°C or less (Hokanson 1977).

There are internal morphological differences between male and female
yellow perch. The ovaries of female yellow perch are a single, fused organ.
Eggs develop in a long cylindrical mass that is interconnected by a gelatinous
matrix. As the female spawns, the thin membrane covering the genital opening
ruptures and the egg ribbon is expelled through the urogenital opening. Male
yellow perch produce milt in pared testes. The milt is expelled from the
urogenital opening via a seminal duct (Schott et al. 1978).

Kayes and Malison (unpublished data) have described a method of sexing

yellow perch greater than 150-mm TL with 70% accuracy. They observed that

40

the urogenital openings of males were round and females were crescent shaped.
When pressure was applied to the abdomen of males, it resulted in the urogenital
opening forming a V towards the point of pressure. When pressure was applied
to the abdomen of females, it resulted in the urogenital opening retaining its
crescent shape. Malison (1999, personal communication) indicated that the
accuracy of this method decreased to nearly 50% when ﬁsh were sexed at less
than 120-mm TL.

A method of creating all female yellow perch has been developed by
Malison and Garcia-Abiado (1986). Yellow perch were fed a diet with
methyltestosterone (MT) at 20-35—mm TL. The female ﬁsh produced ovotestes.
The ovotestes produced sperm that contained only X chromosomes. When the
ﬁsh matured, the ovotestes were removed and the sperm was extracted by
pressing it through cheesecloth. When the milt was mixed with the eggs of a
nonmasculinized female, all offspring produced were XX females. Recently, the
University of Wisconsin-Madison was approved for an INAD (Investigative New
Animal Drug) for the use of methyltestosterone in the masculinization of yellow
perch.

Vitellogenin, a precursor hormone to yolk development, has been used to
successfully determine the sex of stripped bass (Kishida et al. 1992) and carp
(Tyler et al. 1999). They produced an Enzyme Linked lmmunosorbent Assay
(ELISA) to simplify determinations in the ﬁeld. Vitellogenin is produced by the
liver and can be excreted into the slim layer of the ﬁsh. A major shortcoming of

the use of Vitellogenin as a gender identiﬁer is that only females that are in

41

oocyte development produce the hormone. Additionally, Vitellogenin-producing
male rainbow trout have been observed in the wild (Jobling et al. 1996).
Mellanen and co-workers (1996) believe that an increase of phyto-estrogens and
other estrogen-mimicking contaminants may be the cause of the increased
vitellogenic hormone production in male trout.

Many yellow perch producers harvest marketable size ﬁsh from their
rearing units that have been stocked with multiple size and age cohorts. By
continuing to culture the smaller ﬁsh while removing only the large ﬁsh,
producers create a higher proportion of small ﬁsh in their tanks and may
inadvertently select for slower growth. Culling smaller, slower growing yellow
perch might result in a more uniform size distribution. Uniform size distributions
have been shown to increase the growth rate of cultured eels (Wickins 1987) and
limit the hierarchical dominance that is exhibited by some ﬁsh species (Jobling
1982). It has not been determined if yellow perch exhibit a social hierarchy.
These harvest strategies could also lead to unintentional genetic selection for

slower growing ﬁshes (Kapuscinski and Jacobson 1984).

Gender-Related Growth Differences

Yellow perch appear to exhibit compensatory growth. Compensatory
growth refers to an animal’s ability to have a rapid weight gain directly
proceeding a food deprevation or reproductive cycle (Broekhuizen et al. 1994,
Jobling 1994). Compensatory growth occurs in both invertebrates and

vertebrates (Broekhuizen et al. 1994, Russell and Wootton 1992). Hyperphagia

42

and a possible decline in metabolic rate from fasting may have caused the
observed increased weight gain (Ryan et al. 1993).

Estrogenic compounds have been shown to inhibit growth in rainbow trout,
coho salmon, and goldﬁsh (Fagerlund and McBride 1995, 1997; Hirose and
Hibaya 1968; McBride and Fagerlund 1976). However, estrogenic compounds
promote growth in plaice (Cowey et al. 1973) and yellow perch (Malison et al.
1985). When fed to yellow perch, 178-estrogen appeared to promote while
methyl-testosterone appeared to decrease the growth rate by increasing food
consumption rates (Malison et al. 1986). The physiological - behavioral
mechanism by which estrogens increased food consumption has not been

determined.

Saturation Level Kinetics Model

Hill (1911) and Michaelis and Menten (1913) originally developed a model
to describe enzyme kinetics. It was based on enzymatic responses to different
levels of substrate and to varying reaction environmental components such as
pH and temperature. The conceptual model was based on the interaction
between a dependent variable, the observed response (r), and an independent
variable, substrate intake (l). Morgan et al. (1975) expanded the use of the
model to describe physiological responses in animals.

The basic principle behind the model is that for any nutrient (l) given to an
animal, there is a certain response (r) created, whether negative or positive. For

example, an animal given a nutrient (I) along with its speciﬁc receptor (M) will

43

create the complex (Ml), which produces a physiological response (pr) in a

proportional manner to concentration level of (MI), as follows:

 

K1

l+M(-=====-) MI (1)
K2

Pr = K3[M|] (2)

 

(Where K1, K2, and K3 are constants and [] denotes concentration level).
At equilibrium, the combination of the above equations can be written as:
[M] [I] _ K2

[Ml] - K1

=K|

 

(Where Kl is also a constant)
Thus, for the total receptor concentration level (Mt), where [Mt] = [M] + [Ml], or

[M] = [Mt] — [Ml], then:

[Mt-Ml] [l]
-------- = KI

[Ml]
After rearranging:

[Ml] _ ['1
[Mt] KI +[l]

 

When all of the receptors are occupied, the maximal physiological response of

the system (PRmax) is:

 

PR"...x = K3 [Mt] (3)
Then:

pr [Ml]

 

 

PRmax [Mt]
PRmax [I]
Pr = - (4)
K1 4» [I]

The linear model equation of Michealis—Menten ( 1913) from equation (4):

 

Y = a0 + a1X (5)

There are two limitations of equation 4 that do not match the observed
responses. First, responses are found experimentally to be sigmoidal, but this
equation only describes a hyperbola. Adding another parameter (n) to the

equation may solve this limitation:

PRmax [I]n
pr = (6)
K. + “I"

 

 

Where n is the apparent kinetic order.

As n increases above one, the curve of this equation ﬂuctuates from a
hyperbola to a sigmoidal (n>1) curve. This equation has been utilized in enzyme
kinetics (Hill 191 1 ).

The second limitation of the equation deals with the (X, Y) axis system,
which describes a curve that passes through the origin (0, 0) and does not
account for energies used in the metabolism of the nutrient. To solve this, it is
necessary to add the parameter b (the intercept on the ordinate y-axis) to the
previous equation:

PRmax [l]"

45

pr = + b (7)

 

 

 

 

Kl + “I"
Then:
PRmax [1]" + bK. + bl"
pr = (8)
KI "' ['1“

If (PRmax + b) = Rmax and simplify pr to r, the four-parameter mathematical
model for physiology responses can be written:
bKl + Rmaxuln

r = (9)
K. + ['1n

 

 

This canbe also described as:

 

 

DWI)" + Rmaxlll"
,= (10)
(Kin)" + ill"
Where:
r = Physiological observed responses in the ﬁsh,
b = Intercept on the ordinate y-axis.
Km = Intake constant for 1/2 of Rmax,

Rmax = Maximum response,
n = Slope factor (compared to Kr“, apparent kinetic order of the response
with respect to l as In becomes negligible),
| = Nutrient intake.

This model has been successfully used to predict weight gain, nutrient
deposition, dietary requirements, plasma nutrient levels, net nutrients, tissue

enzyme kinetics and other physiological processes in a variety animals (Belal

46

1987; Belal et al. 1992; Mercer 1980; Mercer 1992; Mercer et al. 1989; Mercer et
al. 1993, 1996).

Belal et al. (1992) studied two practical feeds fed to Oreochromis niloticus
ﬁngerlings by using the saturation level kinetic model. Other models that have
been used for the determination of the standard metabolic rate, optimum feed
ration level, growth responses, and protein energy requirements for ﬁsh fed both
practical and natural diets. A similar threshold-corrected hyperbolic model was
used to demonstrate the relationship of the speciﬁc growth rate of Tilapia zillii to
three different feeds (Annett 1985). He also used this model to determine the
relationship between the growth and the size of the ﬁsh to water temperature.

It is important to understand the origin of the model that Annett used.
Pierre-Francsois Verhulst (1845) proposed that during the early stages of
growth, a population would increase exponentially until such time that the critical
resources became limiting. Upon such limits, the rate of growth was retarded in
a symmetrical, sigmoidal curve of growth. This curve, labeled the “logistic growth
model” can be written as:

dN/dt = rN((K — N)IK) (11)

 

Where:

K = maximum carrying capacity

N = number of individuals

r = maximum growth rate (1/time)

t = time

47

Pearl and Reed (1920) used the logistic growth curve to describe the growth rate
of individuals in bacterial and protozoan populations. The logistic growth model
can be used in this manner provided the following criteria are met:

1) both r and K are constant,

2) no time lags exist,

3) all individuals exert an equal effect on the reduction of the growth rate

as population density changes.

When the logistic formula is rearranged to express the rate of increase per unit
time the following equation results:

dN/th = r(1 - (N/K)) (12)

 

Lotka (1925) suggested the reason populations and individuals follow the
same trends was that they had the same basic fundamental mechanisms (e.g.,
individuals are basically large populations of cells).

The logistic growth curve serves the important function of incorporating a
rate dependency concept into growth modeling. Verhulst (1845) claimed that
growth rates would be inﬂuenced by the crucial limiting resource’s availability.
However, the logistic curve fails to relate changing growth rates directly to
speciﬁc environmental resources. The logistic curve describes the growth rate of
a population over time.

In unicellular and multicellular animals, enzymes regulate biochemical
reactions. These reactions contribute to the growth of the organism. Certain
enzymes associate themselves with the substrate to form an intermediate

complex, which act as a catalyst.

48

There are two factors important to the reaction rate, the relative amounts
of enzyme and substrate. At low substrate concentration levels, the reaction rate
would be proportional to the amount of substrate. At these substrate levels, the
enzyme is able to react with all the substrate forming an enzyme-substrate
complex (ES) helping the reaction. As the concentration level of the substrate
increases, a higher percentage of the enzyme is bound in the ES. There are
fewer enzymes to react with the substrate. Eventually, if the substrate
concentration level were to increase sufﬁciently, nearly all the enzyme would be
bound in a complex. This enzyme-substrate reaction rate response has been
described by the Michaelis-Menten equation as follows (Engel 1977):

v = vm(3/(K, + 3)) (13)

 

V = reaction rate (1/time)

Vmax = maximum reaction rate (1/time)

S = substrate concentration level

Ks = substrate concentration level at which the reaction rate is 1/2 Vmax

When 8 becomes very large compared to K3, the reaction rate V
approaches Vmax. When S is very low relative to Ks, the reaction rate is
proportional to S.

Limiting factors (i.e. nutrients or environmental conditions) restricted
bacterial growth (Monod 1949). When experimental conditions were established
to provide an excess of all but one limiting nutrient, and the concentration level of
that limited nutrient is gradually increased, the growth demonstrated an initial

rapid increase. The growth rate then declined until it leveled off at high substrate

49

concentration levels. Monod (1949) established that the relationship is similar to
that determined for the enzyme-catalyzed reactions and proposed the following
equation to relate growth to substrate:

l1 = umaxIS/(Ks + 3)) (14)

p. = Growth rate (1/time)

 

”max = Maximum growth rate (1/time)
S = Substrate concentration level
Ks = Substrate concentration level at which the growth is 1/2 pm

The levels of the constants are an expression of the ability of the enzyme
systems to utilize the particular limiting substrate for growth. This model has one
ﬂaw. The model does not take in account the maintenance value. Subtracting
this value (Sq) will yield the equation:

8 — Sq

F = Hmax (15)
Its - Sq + S- 28(1))

 

 

Dividing both sides by (S - Sq) and inverting yields:

S—Sq S—Sq-i-Ks—Sq

 

 

= (16)
F “max
Then rearranging the equation in the linear form Y = a + bX:
S — Sq Ks — Sq 1
= + (S-Sq) <17)

 

 

 

l-l Hmax llmax
Using this equation, one is able to determine an estimate for the Y-intercept. In a
conversation with Mercer (2000), the model used in this study (equation 10)

requires an estimate for the Y-intercept.

SO

The four-parameter saturation level kinetic model for physiological
response (Mercer 1978) was used to analyze the data:

r = (me +Rmaxln) / (Km + I") (1)

 

Mercer (personal communication) indicated that an estimate of a 0.0 ration level
was necessary to generate equation 1. The 0.0 ration level was estimated using
King’s model:

S—Sq

P = “max (2)
(Ks - Sq + S- 239))

 

 

Equation 2 was rearranged to:

S — Sq Ks — Sq 1
= + (3 —Sq) <3)
I1 “max “max

 

 

 

An efﬁciency parameter that measures the greatest response with the smallest
intake value (Mercer 1982) is described in the equation below:

|me = Km (n — n1," (4)

 

The basal metabolic requirement was determined by setting the response,

r, in equation 1 to 0.

5]

Materials and Methods
Secondary Sex Characteristics

Fish
Yellow perch were obtained from Bayport Aquaculture, West Olive,

Michigan. Approximately 250 ﬁsh, 130: 10 mm total length, were transported to
the Aquaculture Research Laboratory, Michigan State University, East Lansing,
Michigan. All ﬁsh were held and acclimated in a 250-gallon ﬂow-through tank.
Well water from an aerated head tank was supplied at 11.5 i 1°C at a rate of
2.25 exchanges per hour.

A random sample of 40 ﬁsh was taken from the holding tank for
measurements and evaluation of secondary sex characteristics. Fish were
anesthetized by placing them in a solution of MS-222 at a concentration level of
0.5-g/L. Multiple observations and measurements were performed on each
individual ﬁsh.

An otoscope was inserted into the urogenital opening of ﬁsh to determine
if the seminal duct could be observed. A green food-grade dye was used in an
attempt to aid in the identiﬁcation of the seminal duct.

Eye diameter (ED), maxillary length (ML), mouth width (MW), mouth
height (MH), standard length (SL), and total length (TL) were recorded for each
ﬁsh. Ratios between all variables were determined and compared for gender
signiﬁcance. A comparison of means, variances, and standard deviations were
done to identify if further statistical test would be required.

Pressure was applied to the abdomen in an anterior direction to observe

differences in the shape of the urogenital opening. The urogenital opening was

52

also observed under 10X magniﬁcation to identify slight differences in the shape
of the urogenital opening. A food-grade die was used to aid in clarifying any of
the subtle changes in shape.

After observations and measurements were completed, all ﬁsh were
euthanized by placing them in a solution of MS-222 at a concentration level of
1.0-g/L for 10 minutes. The gender of the individual ﬁsh was veriﬁed visually by
dissection and examination of the gonadsThe measurements and observations

were tabulated by gender for analysis of mean, variation, and standard deviation.

Saturation Level Kinetics

This study was designed to determine the effects of gender on growth and
performance of yellow perch greater than 110-mm TL using a saturation level-
kinetics model. All feeding trials were conducted after an initial acclimation
period of two weeks at the Upper River Aquaculture Research Laboratory,
Michigan State University. Fish were acclimated to water and tank conditions
and fed a commercial trout diet, Purina Aquamax Grower 400 from lot A-5DO4,
containing at least 45% crude protein and at least 16% crude lipids. Each
feeding trial was conducted for 16 weeks.
System and water

Feeding trials were conducted in a recirculating aquaculture system
(Appendix 3). Fish were reared in one of 24 gray 110-L experimental culture
tanks. Each tank was equipped with a screened bottom drain and an external

standpipe (Appendix 4). The water exited the tank via the bottom drain, through

53

the standpipe and into a plastic gutter that channeled the water to a primary
solids removal tank. Large solids were removed by passing incoming water
through a screen. The screen was removed and cleaned weekly. Fine
particulate matter was passively removed within a 590-L rectangular settling
tank. Water passed from the settling tank to the bioﬁltration level tank.
Bioﬁltration level was accomplished using a 440-ft2 rotating biological contact
ﬁlter and approximately 0.5-m3 shredded plastic in a bio-bag were used as
bioﬁlter media. Nitrifying bacteria which colonized the ﬁlter media converted
ammonia to nitrite and then to nitrate. The bioﬁltration level tank was heavily
aerated to provide appropriate dissolved oxygen (DO) levels to maintain the
nitrifying bacteria. Water was pumped from the bioﬁlter to the experimental
culture tanks.

Well water was used to ﬁll the reuse system and to replace water lost by
evaporation, cleaning/maintenance, or during weighing procedures. Water
temperature was maintained at ambient room temperature (211-2 °C). Average
water exchange rates were 5.5 L/min. The pH and total ammonia (TAN) of the
culture water were monitored every two weeks. The pH was measured using a
Fisher Scientiﬁc, Accumet model 25 pH/ion meter with the appropriate probe and
calibration. Total ammonia levels were monitored using a HACH ammonia
nitrogen test-kit (model Nl-8). Levels were maintained within the ranges
considered safe for yellow perch (pH ranged from 7.8 to 8.3 and the total

ammonia levels remained below 0.4 ppm).

Fish

Separate stocks of male and female yellow perch were obtained from
Willow Creek Aquaculture (Wautoma, Wisconsin) and transported to Michigan
State University. Fish were separated by gender using the following criteria by
personnel of Willow Creek Aquaculture:

. Males: ﬁsh were selected from a stock of ﬁsh that had been previously
identiﬁed as males. Gender was re-checked by applying pressure to the
abdomen of each individual. Only ﬁsh that produced milt were identiﬁed
as males.

0 Females: ﬁsh were selected from a stock of offspring originating from a
mating between masculinized females and normal females (Malison and
Garcia-Abiado 1986).

Each gender stock was brought to MSU in a separate transport unit. Each
gender stock was held in a separate holding tank at the Upper River Laboratory
for a minimum of two weeks to acclimate them to their new environmental
conditions as described above.

Each experimental culture tank was stocked with eight 110 - 150-mm TL
ﬁsh using a totally random stocking scheme. Tanks were randomly stocked by
the following method:

1. Tanks were assigned to male or female stocks using a random

numbers table.

55

2. A single ﬁsh was taken from the holding tank and placed into the
appropriately assigned experimental tank. Another ﬁsh was not placed
into this tank until all tanks contained an equal number of ﬁsh.

Each experimental culture tank was covered with a screen to minimize the
impact of external visual stimuli from movement around the culture tanks. Fish
were fed three times daily during a two-week acclimation period. Another group
of 8 males and 8 females was euthanized using MS-222 to serve as reference
ﬁsh for proximate analysis.

Feed and Feeding Trials

All ﬁsh were fed a commercial trout diet, PURINA AquaMax Grower 400
(lot A-5D04), containing at least 45% crude protein and at least 16% cmde lipids.
The feed was frozen at ~20°C to maintain freshness throughout the experimental
period. Feeding levels were 0.5, 1.0 2.0 and 4.0% wet-weight/day. The 4.0%
ration level was decreases to 3.0% on day 3 of the experiment because excess
feed accumulated in the tanks fed the 4.0% ration level.

The wet weight of ﬁsh was determined by the following method:

. The tank was drained V2 capacity for easier ﬁsh collection.

. All ﬁsh in a single tank were collected in a net and placed in a tared 2-

gallon pale + water.

. The pale + water + ﬁsh was weighed to the nearest 0.1 gram.

. Fish were placed back in the tank and the water was added to ﬁll the

tank back to the original level.

56

Three replicate tanks of ﬁsh were used for each feeding level and for each
gender. All feed levels were fed three times daily, at 0800, 1300, and 1800-h.
Feed levels were adjusted every two weeks.

Proximate Analysis

At the completion of the growth trials, all ﬁsh were euthanized using MS-
222 at a dosage rate of 1-g/L for a minimum of 10 minutes. Each replicated
group of ﬁsh were ground and stored at temperatures of —20°C. Proximate
analysis of the pre-treatment control, experimental ﬁsh and feed samples were
determined using standard AOAC (1990) methods for moisture, total ash, crude
fat, crude protein, and total gross energy on a dry matter basis. Crude protein
levels were determined for 1-g samples using a Leco 2000 PP nitrogen analyzer
in the Animal Science Department, Michigan State University. Moisture was
determined on 1-g samples at a temperature of 105°C :1 for 48 hours. Total ash
samples were determined for 1-g samples using a mufﬂe furnace for 18 hours at
a temperature of 550°C. Crude fat was determined for lg samples using ether
extraction in a Sockslet Apparatus. A Parr 1241 Bomb Calorimeter was used to
determine gross energy for each tank on 1-g samples. All proximate analysis
values were calculated on a percent dry matter basis.

Feed, protein, lipid, and energy efﬁciency were determined for all ration
level levels and genders. The efﬁciency values were determined based on the
weight of the component (feed, protein, lipid, energy) gained per gram of

component fed.

57

Statistical Analysis

A non-linear regression model provide by Dr. Mercer, University of
Kentucky at Lexington, was used to determine Rmax, Km, b, and n of the
predominately male and female stocks. A one-way ANOVA and Tukey test
(SYSTAT 9, 1999) were used to compare growth, ash, crude protein, crude fat
and gross energy within each gender. A t-test was used to compare between

genders at ration level levels. Differences were considered signiﬁcant if P 5 0.05.

58

Results
Secondary Sex Characteristics

Forty yellow perch, 130.0 1 9.4-mm, were examined to determine the
effectiveness of each potential secondary sex characteristic in determining
gender. The sample of yellow perch was comprised of 23 males and 17 females
as veriﬁed by dissection and examination of the gonads. A comparison, by
gender, of the mean, standard error of the mean, and standard deviation for ED,
ML, MW, MH, SL, TL measurements and the ratios of ED, ML, MW, MH to SL
and TL are summarized in Table 2.1. The similarity of the means and the high
variance and standard deviation indicated that statistical tests were not
necessary to determine if characteristics differed between genders.

An otoscope was inserted into the urogenital opening of all 40 yellow
perch to determine if it was possible to locate the seminal duct of males. No
seminal ducts were observed in any of the male ﬁsh. The use of a food grade
dye did not enhance identiﬁcation of the seminal duct. No seminal ducts were
observed in any ﬁsh.

Using the shape of the urogenital opening while pressure was applied to
the abdomen (Malison and Kayes, in print) was not a reliable method to identify
gender of 130 1 9.4 mm ﬁsh. Only 24 of 40 ﬁsh were correctly identiﬁed to
gender based on the shape of their urogenital opening. Placing a small amount
of food grade dye over the urogenital opening failed to aid in identifying any

morphological differences between males and females.

59

Table 2.1-- The mean, standard error of the mean, and standard deviation for
eye diameter (ED), maxillary length (ML), mouth width (MW), mouth height (MH),
total length (TL), and standard length (SL) by gender for yellow perch (Perca
ﬂavescens), as well as the ratios between ED, ML, MW, and MH to SL and TL.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

MALES FEMALES
MEAN STANDARD STANDARD MEAN STANDARD STANDARD
ERROR OF DEVIATION ERROR OF DEVIATION
THE MEANS THE
MEANS

ED 5.79 0.16 0.58 6.19 0.12 0.63
ML 12.79 0.35 1.31 13.42 0.16 0.81
MW 12.43 0.33 1.22 13.39 0.16 0.80
MH 12.79 0.26 0.98 13.58 0.21 1.07
TL 126.14 2.84 10.61 132.54 1.68 8.56
SL 104.86 2.28 8.55 110.92 1.31 6.69
ED: 0.055 0.002 0.006 0.056 0.001 0.005
SL

ML: 0.122 0.003 0.010 0.121 0.001 0.007
SL

MW 0.119 0.003 0.011 0.121 0.001 0.007
:SL

MH: 0.123 0.004 0.013 0.123 0.002 0.011
SL

ED: 0.046 0.001 0.005 0.047 0.001 0.004
TL

ML: 0.101 0.002 0.008 0.101 0.001 0.006
TL

MW 0.099 0.002 0.009 0.101 0.001 0.006
:TL

MH: 0.102 0.003 0.011 0.103 0.002 0.009

TL

 

60

Saturation Level Kinetics

Originally, we had planned to use the saturation level kinetics model to
compare and contrast differences between all male, all female, and mixed
gender stocks of yellow perch. However, conﬁrmation of the gender of male and
female stocks by dissection indicated that the purported all male stock was
comprised of only 71.2% males while the all female stocks were comprised of
99.0% female (95 of 96). Since our mixed gender stock was comprised of 68.6%
males, a mixed gender experiment was not conducted. The purported all male
stock will be referred to as the predominantly-male stock (PM) in all future
references.

Growth curves were developed for the PM and all-female (AF) stocks of
yellow perch fed varying levels of diet. R2 for growth curves are not presented in
these results since the kinetics model developed by Morgan et al. ( 1975)
maximizes the R2 value. The proximate analysis of the feed and whole body
tissues for each gender group (Table 2.2) were used to calculate the intake and
response relationships for crude protein, fat, gross energy, and ash. Each point
on each ﬁgure represents the mean of three observations at each intake level.
Points above the abscissa represent actual observations of a positive growth

response, The model described by King was used to generate the points below

61

the abscissa (b). The shape of the curves (n), the Km curve parameter, and

calculated maintenance value and optimal value were similar between both

Table 2.2-—- Proximate analysis, on dry matter basis, of a commercial feed,

Purina Aquamax Grower 400 (lot A-5d04) and 1SEM that was fed at ration levels
of 0.5, 1.0, 2.0, and 3.0% body-wet weight per day for 112 days to a
predominately-males stock and an all-female stock of yellow perch (Perca

 

 

ﬂavescens).
Percent Percent Percent Energy Moisture
Protein Lipid Ash (Kcal)
Feed 46111.4 16.4104 9.0101 5.141003 NA
PM 0.5 63.0103 19.0109 12011.6 4.731012 69810.6
AF 0.5 62.2109 22511.2 13.9106 4.731006 68.6107
PM 1.0 59.4121 23913.2 11812.3 4.591076 67.9108
AF 1.0 58810.9 25312.5 8.1129 5.051006 67.1105
PM 2.0 59.9104 23211.7 8.7130 4.921008 67.8105
AF 2.0 61 .7115 25813.1 11.111.7 48910.17 67.6104
PM 3.0 59.5107 22.5107 0411.4 5.091013 68.1106
AF 3.0 61 .1121 27.7112 5.4128 5.251008 67810.4

 

 

62

stocks. The Rmax curve parameter, and ordinate intercept (b) varied between

genders.

63

Growth

Figure 2.1 represents the mean growth rates in grams per day for PM and
AF perch fed a commercial diet. Table 2.3 summarizes the growth parameters
calculated using the kinetics model.

The Rmax which represented the maximum theoretical response, was
signiﬁcantly different between stocks. The Rmax calculated for the PM over the
112-day experimental period was 1.112-g/day/tank while the Rmax calculated for
the AF was 1.853-g/day/tank. The Km (theoretical amount of feed per gram of
ﬁsh that produces a growth response equal to half the Rmax. or the efﬁciency
estimate) observed for male and female stocks (PM=0.575, and AF=0.592) were
not signiﬁcantly different. The calculated slope factor (n) indicated that the
growth response was a sigmoidal shaped curve (n>1) for both genders (Table
2.3).

The D which represented the ordinate intercept or the theoretical response
to a dietary intake of zero, was generated using a kinetics model provided by Dr.
Darrel King (Michigan State University, personal communication); b = -0.348 for
the AF stock and b = —0.1 15 for the PM stock. The calculated numbers were
used to aid in generating the other model parameters. The lr=o which represented
the maintenance level or theortical Y = 0, values were similar between stocks at
0.373 for PM and 0.424 for AF. The lmx (optimum feeding level = a intercept of a

45° line tangent to the growth curve which represents the greatest amount of ﬁsh

 

20 lRmax=1_.850_ '

 

 

Speciﬁc Growth Rate (gm/day)

 

 

J

2 3
Ration (% body weight/day)

 

 

Figure 2.1--- Daily speciﬁc growth rate of male and female yellow perch (Perca
ﬂavescens) (141.5+-11.6 mm TL) reared in a recirculating aquaculture system
fed a commercial diet (Purina AquaMax 400) at 0.5, 1.0, 2.0, and 3.0% body
weight per day for 112 days. A=Females (r2=0.96), =Males (r2=0.88).

65

Table 2.3-- Parameter estimates for Mercer’s saturation level kinetic model for
yellow perch (Perca ﬂavescens) (141.5111.6 mm TL) fed at ration levels of 0.5,
1.0, 2.0 and 3.0% body weight per day for 112 days. Basal metabolic
maintenance level is lag, and optimal feeding level is lmx.

 

 

Parameter Predominately-males All-females
b -01 1 5 -0.348
R...“ 1 .1 12 1 .853
K... 0.575 0.592
n 5.242 4.995
l,.o 0.373 0.424
Imx 0.76 0.78

 

 

66

growth on the least amount of feed) values were similar between genders at 0.76
and 0.78-g/day for PM and AF, respectively.

Maximum feed efﬁciency levels, which represented the greatest rate of
gain per gram diet fed, were calculated for both stocks (Table 2.4). The
maximum calculated feed efﬁciency level was signiﬁcantly greater for female
stocks compared to male stocks at 0.52 and 0.34 grams gained per gram fed for
AF and PM, respectively. The maximum feed efﬁciency levels were achieved at
a feeding rate of 1.0% for both stocks. Feed efﬁciency increased from the 0.5%
ration level to the 1.0% ration level and decreased at ration level levels greater
than 1.0%. However, the feed efﬁciency levels for the AF stock was greater than

the feed efﬁciency for the PM stock at all feeding levels.

Table 2.4-—- Mean feed efﬁciencies (weight gained/weight fed) and 1SEM of
predominately-male and all-female stocks of yellow perch (Perca ﬂavescens)
(141.5111.6-mm TL) fed ration levels of 0.5, 1.0, 2.0, and 3.0% body-wet weight
per day for 112 days. Corresponding letters indicate no statistical difference
between means (p>0.05).

 

 

Ration level (% body 0.5 1.0 2.0 3.0
weight fed per day)

MALE 0.211004ace 0.341005r 0.1710036“6 0.1110016‘
FEMALE 0.231001ad 0.521003b 0.2610013 01710.01ac

 

 

67

Crude Protein

The CP content in Table 2.5 was determined as a percent CP per gram of
dry matter. The mean percent CP level ranged from 59.4 to 63.0 for the PM
stock while the mean percent CP level ranged from 58.8 to 62.2 for the AF stock.
There were no signiﬁcant differences (p>0.05) in percent CP concentration level
within or between genders.
Protein Eﬁiciency

The maximum protein efﬁciency (protein gained for each gram of protein
fed) was determined for both stocks (Table 2.6). The maximum calculated
protein efﬁciency level was signiﬁcantly greater (P = 0.02) for AF stock compared
to PM stock at 0.47 and 0.32 grams gained per gram fed, respectively.
Maximum protein efﬁciencies were calculated for feed levels of 1.0% for both
stocks. Protein efﬁciency increased from the 0.5% ration level to the 1.0% ration
level and decreased at ration level levels greater than 1.0%. The protein
efﬁciency level for the AF stock was greater than the protein efﬁciency for the PM

stock at all feeding levels.

68

Table 2.5-- Mean crude protein levels (% dry matter) and 1SEM of
predominately-male and all-female stocks of yellow perch (Perca ﬂavescens)
(141.5111.6-mm TL) fed ration levels of 0.5, 1.0, 2.0, and 3.0% body-wet weight
per day. No statistical difference was identiﬁed between means (p>0.05).

 

 

Ration level (% body 0.5 1.0 2.0 3.0
weghf fed per day)

MALE 63.0103 50412.1 59.9104 59.5107
FEMALE 62.2109 58810.9 61 .711 .5 61 .112.1

 

 

Table 2.6--- Mean protein efﬁciencies (protein gained/dietary protein) and 1SEM
of predominately-male and all—female stocks of yellow perch (Perca ﬂavescens)
(141.5111.6-mm TL) fed ration levels of 0.5, 1.0, 2.0, and 3.0% body-wet weight
per day. Corresponding letters indicate no statistical difference between means
(p>0.05).

 

 

Ration level (% body 0.5 1.0 2.0 3.0
weight fed per day)

MALE 02110.03ac 0.321005“ 01510028‘ 01010013
FEMALE 0.231001a 0.47102b 02510.01a 0.171001c

 

 

69

Crude Lipids

The percent lipid levels (% lipid/gram of dry matter) are summarized in
Table 2.7. The PM mean percent lipid concentration level ranged from 19.0 to
23.9. The AF mean percent lipid concentration level ranged from 22.5 to 27.7.
No differences (p>0.05) were identiﬁed between stocks. The saturation level
kinetics model was not used to describe the response because of the lack of
signiﬁcance between the treatments and genders.
Lipid Efﬁciency

The maximum lipid efﬁciency (lipid gained for each gram of lipid fed) was
determined for both AF and PM stocks (Table 2.8). The maximum calculated
lipid efﬁciency level was signiﬁcantly greater for AF stock compared to PM stock
at 0.48 and 0.36 grams gained per gram fed, respectively. Maximum lipid
efﬁciencies were calculated at feeding levels of 1.0% wet-weight per day for both
stocks. Lipid efﬁciency increased from the 0.5% ration level to the 1.0% ration
level and decreased at ration level levels greater than 1.0%. However, the lipid
y for the PM

efﬁciency level for the AF stock was greater than the lipid efﬁcienc

stock at all feeding levels.

70

 

Table 2.7-- Mean crude lipid levels (% dry matter) and 1SEM of predominately-
male and all-female stocks of yellow perch (Perca ﬂavescens) ( 141 .511 1.6-mm
TL) fed ration levels of 0.5, 1.0, 2.0, and 3.0% body-wet weight per day. No
statistical difference was identiﬁed between means (p>0.05).

 

 

Ration level (% body 0.5 1.0 2.0 3.0
weight fed per day)

MALE 19.0109 23911.2 23211.7 22.5107
FEMALE 22.5112 25812.5 25813.1 27.7112

 

 

Table 2.8---- Mean lipid efﬁciencies (lipid gained/dietary lipid) and 1SEM of
predominately-male and all-female stocks of yellow perch (Perca ﬂavescens)
(141.5111.6-mm TL) fed ration levels of 0.5, 1.0, 2.0, and 3.0% body-wet weight
per day. Corresponding letters indicate no statistical difference between means
(p>0.05).

 

 

 

Ration level (% body 0.5 1.0 2.0 3.0
wei ht fed er da
MAEE p Y) 0.1810045° 0.3610092‘ 0.1710035!) 0111001"

FEMALE 0.261011” 0.481021” 0.291012“ 0.3110071b

 

n;

71

Energy
The gross energy content (Kcal/gram) results are summarized in Table
2.9. The mean percent gross energy concentration level ranged from 4.73 to
5.25 Kcal/g for AF stocks. The mean gross energy ranged from 4.59 to 5.09
Kcal/g for PM stocks. There were no signiﬁcant differences within gender groups
(p>0.05). The saturation kinetics model was not used to describe the response

because of the lack of signiﬁcance between the treatments and genders.

Energy Efficiency

The maximum energy efﬁciency (energy gained for each gram of energy
fed) was determined for AF and PM stocks (Table 2.10). The maximum
calculated energy efﬁciency level was greater for AF stocks compared to PM
stocks at 0.53 Kcal and 0.31 Kcal gained per Kcal fed, respectively. Calculated
maximum energy efﬁciencies were observed at feeding levels of 1.0% wet-weight
per day for both stocks. Energy efﬁciency increased from the 0.5% ration level to
the 1.0% ration level and decreased at ration level levels greater than 1.0%.

However, the energy efﬁciency level for the AF stock was greater than the

energy efﬁciency for the PM stock at all feeding levels.

72

Table 29—— Mean energy levels (Kcal/gram) and 1SEM of predominately-male
and all-female stocks of yellow perch (Perca ﬂavescens) (141.5111.6-mm TL) fed
ration levels of 0.5, 1.0, 2.0, and 3.0% body-wet weight per day. Corresponding
letters indicate no statistical difference between means (p>0.05).

 

 

Ration level (% body 0.5 1.0 2.0 3.0
weight fed per da y)

MALE 4.731012a 4.5910793 4.9210085F 5.0910135"—
FEMALE 4.731000a 50511.00ab 4.8910173" 5.251003b

 

 

Table 2.10-- Mean energy efﬁciencies (Kcal gained/dietary energy) and 1SEM
of predominately-male and all-female stocks of yellow perch (Perca ﬂavescens)
(141.5111.6-mm TL) fed ration levels of 0.5, 1.0, 2.0, and 3.0% body-wet weight
per day. Corresponding letters indicate no statistical difference between means

 

 

(p>0.05).

Ration level (% body 0.5 1.0 2.0 3.0
weight fed per day)

MALE 020100335 03110.05ac 0.17100?” 01110.01"—
FEMALE 0.2310013 0.53103c 0.2610013 0.2010018

 

 

73

 

Ash
The mean ash level at each ration level for AF and PM stocks are
summarized in Table 2.11. The mean ash level ranged from 5.4 to 13.9 percent
for AF stocks. The mean ash level ranged from 6.4 to 12.0 percent to PM stocks.
The mean ash level (% dry matter) of whole yellow perch tissue differed between
the 0.5% ration level and the other three ration levels fed to AF stocks. There

was no signiﬁcant difference (p>0.05) between ration level levels for PM stocks.

Table 2.11-- Mean ash levels (% dry matter) and 1SEM of predominately-male
and all-female stocks of yellow perch (Perca ﬂavescens) (141.5111.6-mm TL) fed
ration levels of 0.5, 1.0, 2.0, and 3.0% body-wet weight per day. Corresponding
letters indicate no statistical difference between means (p>0.05).

 

 

Ration level (% body 0.5 1.0 2.0 3.0
_w_eight fed per da y)
MALE 12.01183" 11012.29a 3712.975" 6.4118535

FEMALE 13.91003a 3.112.237ab 11.11100ab 5.41201b

 

 

74

Discussion

The primary focus of this discussion is on the determination of the
bioenergetic responses of male, female, and mixed gender populations of yellow
perch which may help commercial farmers develop culture strategies to avoid
gender based growth differences. Previous research has not focused on the
bioenergetic implications of gender on differences in growth.

Secondary Sex Characteristic

Although many ﬁsh exhibit sexual dimorphic characteristics, yellow perch
genders are not readily distinguishable by color or other gross anatomical
features. A reliable secondary sex characteristic to identify the gender of 130 1
9.4 mm yellow perch was not identiﬁed. No differences were identiﬁed between
the ED, ML, MW, and MH of male and female yellow perch. The ratio of ED to
TL was not different between genders of yellow perch. Female eels (Buellens et
al. 1997) had a smaller eye diameter to total length ratio than male eels.

Since female yellow perch do not have an ovoduct connected to the
urogenital opening (Schott 1978), it was hoped that we could identify males by
the presence of a duct entering the urethra. However, the point of attachment of
the seminal duct to the urethra could not be located using an otoscope to identify
males. Adding dye to the urogenital opening did not enhance our ability to
visually locate the duct.

Malison and Kayes (unpublished data) indicated that pressure applied
anterior to the abdomen of yellow perch greater than 110-mm TL caused the

urogenital opening to appear V-shaped in the females and crescent shaped in

75

the males. They indicated that they successfully identiﬁed 80% of the gender of
yellow perch using this method. However, we only observed a 60% success rate
using this method. In conversations with Malison, he noted that the success rate
decreased with smaller-sized ﬁsh. Although they observed a success rate of
80% overall, the gender of only 60% of ﬁsh less than 150 mm were accurately
identiﬁed while the gender of nearly 100% of the ﬁsh over 150 mm were correctly
identiﬁed. The ﬁsh used in our study had never spawned, while the larger ﬁsh
used by Malison and Kayes (unpublished data) may have spawned once. When
female ﬁsh spawn, eggs rupture through a thin membrane and exit the urogenital
opening. If the female ﬁsh had spawned, the resulting scar tissue interior to the
urogenital opening may have stretched differently compared to non-scar tissue of
younger, non-spawned female ﬁsh and male ﬁsh.
Saturation Level Kinetics
The primary goal of this study was to use the saturation level kinetic model
(Morgan et al. 1975) to describe growth of yellow perch as a function of dietary
intake. The growth parameters for the saturation level kinetics models were
generated using the variable wet weight gain between feeding levels as the
response. Weight gain can be calculated at any intake level using the model
equation after estimating the parameters (Rm. Km. b) I"1x and 17:0. Each of these
parameters interacts with one another either directly or indirectly. Rmax, Km, n,
and b deﬁne the response by the following equation;
NM)" + Rmaxl"
”(I‘ll)" + 1"

 

r:

76

 

The maximum ration level originally fed in this study (4%wet eight per day)
was one percent higher the maximum feeding rates used by commercial yellow
perch producers in the North Central Region (personal communications, S.
Genson, Willow Creek Aquaculture, WI and C. Starr, Bay Port Aquaculture, MI,
1998). Commercial yellow perch producers typically feed at a rate of 3%-wet
weight per day. Based on the highest feeding rate, replicate tanks of ﬁsh were
fed decreasing graded levels of 2.0, 1.0, and 0.5% of body-wet weight/day. After
the initiation of the growth trial, ﬁsh feed the 4.0% rate did not consume all feed
fed. Consequently, the maximum rate was reduced to 3.0%.

Initially, we had anticipated that the ﬁsh fed at 0.5% rate would loose
weight; however, ﬁsh fed at the 0.5% rate exhibited a positive growth response.
A negative growth response was needed to generate Rm, Km, and n parameters
using the model developed by Morgan et al. (1975). A model described by Dr.
Darrel King (personal communication) was used to determine a theoretical
starvation point equal to the response at a ration level of 0.0% per day. The
theoretical starvation point was used with observed growth responses to
generate the growth curves for AF and PM stocks (Table 2.3).

Melard et al. (1996) calculated the growth response of a mixed gender
stock of European perch, Perca ﬂuvitilis, using a four-parameter saturation level
kinetics model (Mercer 1982). The maximum growth response for P. ﬂuvitilis was
1.8—g/day for ﬁsh up to 300 grams total wet-weight. The maximum growth
response for yellow perch in our study was calculated as 1.85 and 1.11-g/day for

AF and PM stocks, respectively. The ration level for optimum growth efﬁciency

77

for European perch was 1.0% wet weight per day compared to 0.78% and 0.76%
wet weight per day calculated for the AF and PM yellow perch stocks,
respectively. Other kinetics parameters were similar between the two studies.
The greater responses observed by Melard et al. (1996) for mixed stocks may
have resulted from a larger percentage of females in their stock compared to our
PM stock. However, the gender ratio was not reported in their study.

The maximum growth rate of the PM stock was approximately 60% of the
growth rate of the AF stock. Only a slight difference was found when comparing
Imx or lr=o between genders. This observation implies that females were more
efﬁcient at converting feed into body mass at ration level levels greater than 1%.
This result corresponds with the earlier observations that female yellow perch
grow faster than males once the ﬁsh reaches a TL of 100 to 110-mm (Malison et
al. 1985 and 1986, Malison and Garcia-Abiado 1996, Schott et al. 1978).

Proximate Analysis

The whole body proximate analysis values for protein, lipid, ash, energy,
and moisture content determined in our study were similar to the values
observed by Rienitz and Austin (1980) and Tidwell et al. (1999). Rienitz and
Austin (1980) compared growth and whole body proximate analysis between ﬁsh
fed four potential yellow perch diets. The proximate analysis of the ﬁsh fed a diet
containing 53.1% crude protein and 15.4% crude fat yielded crude protein, crude
fat, and ash levels of 66.7, 16.5, and 15.3% dry weight, respectively. We
observed crude protein, crude fat, and ash levels of 60.7, 23.7, and 9.7% dry

weight, respectively when fed a diet containing 46.1% crude protein, 16.4%

78

crude fat, and 5.14% ash. This may account for the slight differences observed
in whole body proximate analysis between the two studies. Tidwell et al. (1999)
compared growth and whole body proximate analysis of yellow perch fed a
commercial salmonid diet containing 45% crude protein and 16% crude lipid
three temperatures, 20, 24, and 28°C. The body composition of their ﬁsh did not
differ between any of the temperatures. At the 20°C treatment, the level of whole
body crude protein, crude fat, and ash levels were 59.7, 27.5 and 11.1%,
respectively. The elevated crude fat level observed by Tidwell et al. (1999)
compared to our study may have been an affect of not separating the genders or
females producing eggs.

Whole body crude protein levels as a percent of dry weight were not
signiﬁcantly different between genders or within gender stocks regardless of
ration level in our study. Robards et al. (1999) compared whole body crude
protein and lipid/energy composition of sand lances (Ammodytes hexapterus) by
gender and season from a capture ﬁshery. They observed that crude protein did
not differ signiﬁcantly between genders.

Whole body lipid content of the AF stock was not signiﬁcantly higher than
the whole body lipid content of the PM stock (Table 2.7) even though many of the
females had developing eggs by the end of our study. Gonad development
affects the growth rate of yellow perch (Hayes and Taylor 1990). They found that
the growth rate slows as yellow perch reach sexual maturity. Robards et al.
(1996) determined that the lipid and energy content in female sand lances was

greater than the lipid or energy content in the males. The gender differences in

79

lipid or energy content only appeared once the sand lances reached a TL greater
than 80-mm and female ﬁsh increased lipid stores during egg production. Fish in
our study may not have reached that level of egg development. Hokanson
(1977) determined that yellow perch require a 160-day chilling period (water
temperature less than 6°C) for proper egg development. Fish in our experiment
were maintained at a constant temperature of 21°C.

Typically, digestion efﬁciencies in ﬁsh have been observed to decrease as
feeding levels increase (Smith 1978). Figures 2.2, 2.3, and 2.4 compare protein,
lipid, and energy digestion efﬁciencies, respectively, between gender stocks at
the four ration levels fed. At the 0.5% body-wet weight/day ration level, the
calculated digestion efﬁciencies for AF and PM stocks were lower than the
digestion efﬁciencies calculated for the 1.0% body-wet weight/day ration level.
The lower digestion efﬁciencies were probably due to the use of the dietary
components for maintenance energy. The lower digestion efﬁciencies calculated
at feed rates greater than 1.0% body-wet weight/day were probably caused by
reduced conversion of the feed to tissue. The decline in digestion efﬁciency at
ration levels greater than 1.0% body-wet weight/day were caused by over
feeding. The calculated digestion efﬁciency values were similar to those reported
by Fiogbe’ et al. (1996) for juvenile P. ﬂuviatilis. Fiogbe’ et al. (1996) determined
that the protein efﬁciency was 0.38 grams of protein grained for a gram of protein
fed. Juvenile ﬁsh used much of their dietary energy for somatic growth during a

growth phase characterized by a rapid increase in body size. Because female

80

.0
o:

 

 

 

 

 

 

 

 

 

 

r:
3’ EO'5 T
e '0
0- 2
5:0.4
5 303 IPMj
2 .92 CIAF
E Q J
g E
5 00.1

O

0.5 1 2 3

Ration

Figure 2.2—- Mean protein efﬁciencies (protein gained/dietary protein) of
predominately-male (PM) and all-female (AF) stocks of yellow perch (Perca
ﬂavescens) (141.5111.6-mm TL) fed ration levels of 0.5, 1.0, 2.0, and 3.0% body-
wet weight per day for 112 days. Y-bars represent the standard error of the
mean.

81

 

 

 

 

 

 

 

 

 

 

 

a 0.8
8
'13 0.7 ”I
E 0.6
I 8. 30.5
:5. ~93 I PM
L—Z '9 0'4 DAF
g? g 0.3
.2 +
» o
‘5 0.2 ]
1, 0.1 -
'5.

0.5 1 2 3

Ration

Figure 2.3-- Mean lipid efﬁciencies (lipid gained/dietary lipid) of predominately-
male (PM) and all-female (AF) stocks of yellow perch (Perca ﬂavescens)
(141.5111.6-mm TL) fed ration levels of 0.5, 1.0, 2.0, and 3.0% body-wet weight
Per day for 112 days. Y-bars represent the standard error of the mean.

82

.0
o:

 

.09
#01

 

 

IPM
DAF

 

 

9.0.0
moo

Energy Efficiency (Energy
Gained/Dietary Energy)

 

 

 

 

 

   

O

0.5 1 2 3

Ration

Figure 2.4-- Mean energy efﬁciencies (energy gained/dietary energy) of
predominately-male (PM) and all-female (AF) stocks of yellow perch (Perca
ﬂavescens) (141.5111.6-mm TL) fed ration levels of 0.5, 1.0, 2.0, and 3.0% body-
wet weight per day for 112 days. Y-bars represent the standard error of the

mean.

83

‘li

he

ﬁsh used in this study had initiated egg development, some energy was directed
toward gonadal development. This could account for the slight differences in
protein efﬁciency between this study and Fiogbe’ et al. (1996).

The whole body lipid digestion efﬁciencies for the AF at feed rates greater
than 1% wet-weight per day may indicate that females hand an increased ability
to assimilate lipids from the diet. The developing eggs within the AF stock may
have caused the increase lipid efﬁciencies in ﬁsh fed at 3.0% of their body-wet
weight, because the major component of a ﬁsh eggs is lipids. The different
energy content of male and female energy content may be explained by the
increased amount of lipid in the females. According to Fish Feed Technology
(1978), lipid has a gross energy level of 9.0-Kcal/g where as the protein has a
gross energy content of 5.65-Kcal/g. Since the females contained eggs, a
slightly higher gross energy content would be observed when comparing the AF
and PM stocks.

Feed efﬁciency (Figure 2.5) followed the same response pattern as
protein, lipid, and energy digestion efﬁciencies (Figures 2.2, 2.3, 2.4). This
should be expected since the feed efﬁciency response is a combination of
nutritional factors relative to the weightgained by the ﬁsh. No differences in feed
efﬁciency were observed between genders at the 0.5, 1.0%, and 2.0% wet-
weight per day ration level levels. However, signiﬁcant differences were
observed between genders fed at the 3.0% wet-weight per day ration level. This

indicated that the AF stock was more efﬁcient at converting the feed into body

84

 

 

 

 

 

 

 

E (16
3%, 05‘
52$ 04‘
.9 CA lPM
1:133 03 AF
I.” U?"- 02 E]
“E
8.9 01“
k 1

E: O

1 2 3 4
Futon

 

 

 

Figure 2.5-- Mean feed efﬁciencies (weight gained/weight of feed fed) of
predominately-male (PM) and all-female (AF) stocks of yellow perch (Perca
ﬂavescens) (141.5111.6-mm TL) fed ration levels of 0.5, 1.0, 2.0, and 3.0% body-
wet weight per day for 112 days. Y-bars represent the standard error of the
mean.

85

mass compared to the PM stock which corresponds to the ration level levels fed
by commercial yellow perch producers.

The calculated efﬁciency values indicated that the AF stock had a greater
feed assimilation at the 3.0% ration level compared to the PM stock. As the feed
rate was lowered (became restricted), the response between genders was
similar. Similarty, both stocks had comparable basal metabolic requirements
(Ir-=0). A signiﬁcant difference in growth was observed between the AF and PM
stocks at a ration level greater than or equal to 1.0% wet-weight per day. The
1.0% wet-weight per day ration level appeared to be near the optimal ration level
for yellow perch fed the diet used in our study. The growth rate for the PM stock
fed at the calculated optimal ration level (lmx) was 0.88 g/tank/day, whereas the
growth rate for the AF stock at the calculated optimal ration level (lmx) was 1.41
g/tank/day. The AF stock had a 38% greater growth response compared to the
PM stock.

A large variance was observed in the ash levels within both gender stocks.
Mean ash levels greater than 12.0% and lower than 6.0% were observed for both
stocks. A few ash samples were observed that contained relatively large bone
fragments. This indicated that the samples may not have been completely
homogenized. This could have accounted for the high variation within stocks fed
at the same feed ration level.

Gender related differences in feeding behavior could account for the
differences in growth rates between the AF and PM stocks. In this study, the

majority of yellow perch in the PM stock did not aggressively feed when the feed

86

was fed. The AF stock demonstrated a more uniform and aggressive feeding
activity when the feed was fed.

Frequency of feeding and time between feeding may also affect the utilization
of feeds. Nile tilapia grew more efﬁciently when fed 3 times daily instead of 5
(Riche 2000). Riche (2000) also observed that the optimal interval between
feedings was 4 — 5 hours, depending on the energy and composition of the diet.
Shorter time intervals between feedings increased gastric motility and reduced
digestion efﬁciency. Perca ﬂuvitilis grew best on restricted food supplies (< 2.0%
wet body weight/day) if the feed was evenly distributed over 6 feedings per day,
however, the ﬁsh grew best when fed only 3 times daily if the ration level was
2.0% wet-weight per day (Kestemont and Melard 1996). Yellow perch were fed
three times each day at time intervals of approximately 4 hr in our study. The
Optimal number of feedings and time interval between feedings should be
determined for yellow perch to ensure that the gastric mobility is paired with the
efﬁciency of processing and absorbing the feed.

The mixed gender PM stocks may have limited our ability to statistically
differentiate between yellow perch genders when comparing calculated growth
parameters and proximate analysis values. The PM stock was 18% female and
the AF stock was 99% female. The ﬁsh within the AF stock were more uniform in
size then those of the PM stock. This may have been the result of the number of
females within the PM stock. The females within the AF stock tanks may have

consumed similar amounts of food resulting in a more uniform sized distribution

87

while the females in the PM stock tanks may have consumed larger portions of

the ration level resulting in a larger sized variance.

88

Summary and Conclusion

Secondary sex characteristics could not be identiﬁed to reliably identify the
gender of yellow perch. The PM stock contained 18% females while the AF
stock was 99% female. The mixed gender PM stocks may have limited our
ability to statistically differentiate between the gender stocks when comparing
calculated growth parameters and proximate analysis values. Therefore, without
a reliable means to separate genders, commercial yellow perch producers
cannot develop strategies to separate stocks.

The growth of the AF stock was signiﬁcantly greater than PM stock when
ﬁsh were fed at 3% body weight per day. At ration levels of 2% or less, the
observed growth rates of the gender stocks were not signiﬁcantly different.
However, at the calculated optimal ration level (Imx) of 08% body weight per day
(Morgan et al. 1975), the female growth rate was projected to exceed the growth
rate of males by nearly 1.5 times. The digestion efﬁciency of both stocks
followed a similar pattern to the growth response. The greatest digestion
efﬁciency was observed for the feed rate of 1.0% per day.

Other researchers have focused on developing technologies to culture
female stocks to avoid differences in gender based growth differences. This
strategy would decrease the time required to culture yellow perch to marketable
size. Future research should focus on the development of a balanced yellow
perch feed and feeding strategies that optimize the growth of both genders. The

optimal number of feedings and time interval between feedings should be

89

determined for yellow perch to ensure that the gastric mobility is paired with the
efﬁciency of processing and absorbing the feed.

Genetic selection and domestication of yellow perch may also increase
growth rates and decrease gender-based differences in growth. Genetic
selection of the fastest growing male and female perch reared under intensive
culture conditions should decrease the high variability in growth rates among the
offspring of wild captured yellow perch. This may decrease the length of grow-out

time for yellow perch.

9O

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91

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100

APPENDICES

101

APPENDIX 1

Artemia Culture

Two-liter soda bottles were modiﬁed and used for culture tanks. The
bottom of the bottle was removed. An air stone was glued through the cap of the
bottle. The bottle was inverted and supported on a ring stand. Approximately
1.75 liters of water was added to each of the ﬁve culture tanks. Aeration was
supplied gently to each tank. One gram of NaCl was added to the water.
Artemia spp. (Great Salt Lake strain) cysts, 0.5-g, were stocked into the culture
tank. Constant light was supplied. The initiation of the cultures was staged so
that the ﬁrst hatch nauplii would be ready at the appropriate feeding time, 24-h
after stocking cysts.

Artemia spp. were harvested by turning off the aeration and allowing the
cyst shells to settle for 15 minutes. All room lights were turned off and a single
light was placed beside the bottle to concentrate the Artemia. A siphon was used
to extract the congregated Artemia spp. All Artemia spp. were placed into a
graduated cylinder. Water was added to bring the level to 200ml. The Artemia
spp. was mixed thoroughly and 50ml were placed into four separate beakers.
Each beaker was used to feed a single tank. This process was repeated 5 times

daily.

102

APPENDIX 2

Vinegar Eel (Tirbatrix aceti) Culture

Three gallons of apple cider vinegar was mixed with two gallons of water
in a 6 gallon pale. One large apple was cut into slices and added to the diluted
vinegar. The solution was loosely covered and stored at room temperature.
After 6 weeks, a sample was analyzed to determine the presence of vinegar eels.
Vinegar eels were present at a high concentration.

Prior to feeding, the vinegar eel culture tank was stirred to evenly
distribute the nematodes. A 4 X 4-in scrub pad was submerged in the solution.
The scrub pad was rinsed with well water into a 1L beaker. The content of the
beaker was diluted to 1-L. A subsample of 250-ml of the mixture was poured Into
4 separate smaller containers. Each container was used to feed one tank. This

process was repeated for each of the ﬁve feedings.

103

APPENDIX 3

Appendix A, 3.1- The recirculation aquaculture system used to rear yellow
perch (Perca ﬂavescens) for 112-day experimental period. Water was pumped
from the bioﬁlter, rotating biological contact ﬁlter and shredded, to the
experimental culture tanks. The water ﬂowed from the experimental culture tanks
into a gutter system that channels the water into a primary solids removal
system, screens. Small-suspended solids were passively removed in a large
settling tank. Water exited the passive solids removal tank and entered the
bioﬁlter.

 

 

 

 

 

 

 

 

 

 

 

 

Experimental Tanks 8 Id
[12 tanks] 0' s
Removal
] Screen
[large]
1 Settling
[fine]
Pump
Biofilter
Experimental Tanks
[12 tanks] NH4to N02 to N03

 

 

 

 

104

APPENDIX 4

Appendix A. 4.1- Water depth was determined by the height of the external
standpipe. A ball valve at the tanks lowest point aided in large solids removal by

allowing a small settling area above the valve. Opening the valve removed all
the accumulated solids.

 

 

 

 

 

 

 

 

 

:XWater inflow
D14"
L__J
Experimental Tank
External
Standpipe
Exit
_ _1 — L—
Ball valve

(External standpipe used in the recirculating aquaculture system to rear yellow
perch (Perca ﬂavescens».

105