Malison, J. A,, and J. A. Held. 1995. Habituating pond-reared fingerlings to formulated feed. Pages 

199-204 in R. C. Summerfelt, editor. Walleye culture manual. NCRAC Culture Series 101. North 

Central Regional Aquaculture Center Publications Office, Iowa State University, Ames. 

Habituating Pond-Reared 

Fingerlings to Formulated 

Feed 

Jeffrey A. Malison and James A. Held, University of Wisconsin-Madison Aquaculture Program, Department of 

Food Science, 123 Babcock Hall, Madison, WI 53706 

The development of a commercial industry that 

produces food-size walleye is contingent upon a reliable 

and inexpensive supply of fingerlings that are habituated to formulated feeds. In addition, the use of feedtrained fingerlings would probably reduce the production cost of advanced fingerling walleyes (i.e., fingerlings longer than 2-3 in [50-75 mm] in total length 

[TL]) that are currently raised by resource management 

programs using natural foods or forage fish (Nagel 

1974). 

One way to produce fingerling walleyes habituated to 

formulated dets is by using intensive tank culture 

techniques. Another possibility that is currently being 

tested is to feed-train fingerlings while they remain in 

ponds. This new method uses lights, sound, or both to 

attract fingerlings to the vicinity of automatic feeders, 

and it has met with some success (our unpublished 

observations). To date, however, the most widely 

practiced method of producing feed-trained fingerlings 

has been to rear walleye in ponds until the fish reach 1- 

3 in (25-75 mm) in TL, and then harvest and stock the 

fingerlings into tanks for habituation to formulated 

feeds (Colesante et al. 1986). This method, sometimes 

called the “tandem pondtank technique” (Moore et al. 

1994), is the focus of this chapter. 

Many terms have been used to describe the process of 

replacing live food organisms with formulated diets, 

including “habituation,” “feed-training,” “conditioning,” 

“conversion,” or “acclimation”. We prefer the term 

“habituate” because it can be used to describe both the 

behavioral responses of fish as well as the actions of 

culturists. “Condtion,” “acclimation,” and “feedtraining” are also reasonably accurate terms. The term 

“conversion,” however, is commonly used to describe 

“a change from one form or use to another”. Accordingly, “conversion” does a poor job in describing the 

habituation process, since fingerlings change neither 

form nor use. Even more importantly, the use of the 

term “feed conversion” to describe the habituation of 

fingerlings can lead to considerable confusion, since 

feed conversion is also commonly used to describe the 

ratio of the weight of feed consumedhody weight gain. 

Just as there is no clear consensus of the terminology 

used to describe the habituation process, there is no 

unanimity among walleye culturists as to protocols that 

optimize the production of feed-trained fingerlings. The 

impact of subtle but significant differences in fingerling 

size and condition at harvest, culture conditions, disease 

treatments, food types, and feeding strategies are 

described both in this chapter and in the accompanying 

case studies. In ths chapter, we have also included 

some of the more recent research findings from our 

laboratory that pertain to habituating pond-reared 

walleyes to formulated feeds. 

The habituation process begins shortly after walleye 

fingerlings are harvested from ponds, usually when fish 

reach 1-3 in (25-75 mm) in TL. Typically, when 

walleye are harvested at this size, 50,000-1 50,000 

fingerlingdacre (1 25,000-375,000/ha) can be produced. 

Harvesting walleye once they have reached larger sizes 

usually results in lower yields. The most serious 

problems confronted when rearing walleye fingerlings 

NCRAC Culture Series 101 - Walleye Culture Manual 199 
to larger sizes on natural forage are cannibalism and the 

depletion of the natural forage base (Dobie 1956). 

Alternatively, the number of fingerlings that can be 

produced in a pond can be maximized by harvesting the 

fish at a small size. The fragile nature of walleye less 

than 1 in (25 mm) in TL, however, can make them 

dfficult to harvest. Additionally, fish harvested at too 

small a size may not habituate well to conventional 

starter diets (Cheshire and Steele 1972). In one study 

undertaken by our laboratory, the habituation rate of 

walleye harvested at 1.2 in (30 mm) in TL was greater 

than that of fish harvested at 0.8 in (20 mm) in TL 

(Figure 1). The overwhelming cause of mortality in the 

small fingerlings was starvation, Whether this high 

incidence of starvation resulted from a direct behavioral 

response of the small fingerlings (e.g., lack of recognition or acceptance of formulated feeds) or from indrect 

causes (e.g., handling stress) was undetermined. 

Stress or injury suffered by fingerlings during harvest, 

transportation, size-grading, and routine husbandry 

procedures can result in high levels of mortality during 

the habituation process. Box A in Figure 2 highlights 

the mortalities that we observed in a group of walleye 

fingerlings that were subject to stressful conhtions 

during transport from pond to tank. In addition to 

leading directly to death, stresses caused by careless 

handling combined with the ordeal of the habituation 

process provide the perfect opportunity for disease 

outbreaks (Hussain and Summerfelt 1991 : Kuipers and 

Summerfelt 1994). A great deal of vigilance of the fish 

culturist as well as continuing refinements of fish 

handling procedures are needed to minimize stressrelated problems during this critical time (Nickum 

1986). 

The decision to harvest a crop of walleye fingerlings 

and begin the habituation process is usually not as 

simple as choosing the specific fish size or age to 

harvest. While the fish must reach a minimum size to 

accept conventional starter feeds, other variables such 

as size uniformity, the overall condition of the fingerlings, and environmental conditions (e.g., pond water 

temperature, dissolved oxygen, zooplankton density, 

etc.) should have a significant impact on when ponds 

are harvested. 

As a general rule, the better the condition of fingerlings 

at harvest the more successfully they will adapt to 

formulated feeds and intensive culture con&tions. Poor 

fish condition at harvest can result from declining 

forage bases or overpopulated ponds. In some instances 

we have observed visibly emaciated fingerlings, while 

60 1 ............................................................................................... 

. , . , . . , . , . , . . , . , . , . , . . , . , . , . . , . , . , . , . . , . , . , . . , . , 

HABITUATED STARVED CANNIBALIZED 

Figure 1. Percentage of walleyes habituated to formulated feeds, or lost to starvation or cannibalism after 

being harvested from ponds at 0.8 in (20 mm) or 1.2 in 

(30 mm) in total length. Each bar represents the mean 

f sem of 3 tankshreatment. Both groups of fingerlings 

were harvested from ponds containing adequate 

forage bases; condition factors of the fingerlings at 

harvest were similar; and fish appeared robust and 

healthy. The diet used for feed-training was Ziegler 

Bros., Inc. (Gardner, PA) salmon starter. 

still in the pond. Regardless of cause, fingerlings 

in poor condition rarely have the energy reserves 

needed to successfully withstand harvest stresses 

combined with a period of adaptation to a new 

food source and a novel environment (Figure 2, 

Box B, opposite page). In our experiences, 

smaller but more robust fingerlings will habituate more successfully than larger but thinner and 

weaker fingerlings. 

Size uniformity within a group of walleye 

fingerlings is another important determinant for 

deciding when to harvest a pond. The opportunity for differential growth increases with an 

extended pond phase of production, particularly 

in the face of a declining forage base (Nickum 

1986; McIntyre et al. 1987). Large variations in 

size can lead to high incidences of cannibalism 

(Cuff 1977) during the habituation period when 

starving cohorts may be a more attractive food 

source than formulated feed. Li and Mathias 

(1 982) attributed a decline in cannibalism rates 

among juvenile walleye (longer than 0.75 in [20 

200 NCRAC Culture Series 101- Walleye Culture Manual 
1 ~ ..... * I' .______._, I ....................................................... i B. 

2 40 

$ r condition 

37 mm TL 

20 

0 

0 10 20 30 

DAYS AFTER HARVEST 

Figure 2. Percent survival of walleye fingerlings 

harvested at 1.6 in (40 mm) or 1.5 in (37 mm) total 

length and habituated to intensive culture conditions and formulated feeds. Fingerlings identified 

as being in good condition were harvested from a 

pond containing an adequate forage base; those 

identified as being in poor condition were harvested from a pond containing a depleted forage 

base, and were visibly emaciated at harvest. The 

diet used for feed-training was Ziegler Bros., Inc. 

(Gardner, PA) salmon starter. 

mm] in TL) to minimal size differences among the fish. 

Nagel (1 974) and Nickum (1 986) suggested that sizegrading fingerlings prior to and during the habituation 

period will help control cannibalism. While this 

practice does reduce cannibalism, the stress and injuries 

caused by frequent size-gradmg can also be detrimental 

to survival. 

The environmental conditions under which fingerlings 

are habituated have a significant impact on the habituation success. Starvation generally stems from nonacceptance of the formulated &et, but has also been attributed 

to sub-optimal environmental conditions (Cuff 1977; 

Masterson and Garling 1986). Corazza and Nickum 

(1 983) found that light-colored tanks had a negative 

effect on the feeding response of juvenile walleye. 

Similarly, Masterson and Garling (1986) found that 

color contrast between the feed and tank improved feed 

acceptance. Using walleye fry, Bristow and Summerfelt 

(1 994) recently reported that increased water turbidity 

improved feed acceptance of tank-reared fry, but 

whether turbidty improves habituation of fingerlings 

has not been determined. 

Several environmental variables can improve feed 

acceptance by increasing the frequency or duration 

that the fingerlings are exposed to food. Working with 

walleye fry, Howey et al. (1 980) suggested that light 

could be used to concentrate fish under automatic 

feeders and reduce the length of time required for fish 

to begin actively feeding. In yellow perch, we 

demonstrated that habituation could be improved by 

using in-tank lighting to attract fingerlings to feeders 

(Malison and Held 1992). Upwelling water flows that 

suspend food in the water column can also improve 

habituation (Masterson and Garling 1986). Nickum 

(1986) recommended lighting for at least 16 h daily, 

and our laboratory and others (Beyerle 1975) routinely use continuous lighting (24 ldday) during the 

habituation process. 

Observations made by ourselves and others (Nagel 

1976, 1978) inhcate that walleye are easily hsturbed 

by shadows and movement. These dsturbances can 

interrupt feeding for several hours. Nagel (1 985) 

suggested that tank covers and in-tank lighting can 

minimize such disturbances. We have observed 

behavioral hfferences between fingerlings habituated 

using in-tank versus overhead lighting and, in general, 

walleye reared using in-tank lighting seem to be less 

disturbed by routine husbandry procedures. However, 

the results of several experiments in our laboratory have 

been inconsistent, and we have found no conclusive 

evidence that in-tank lighting results in improved 

habituation rates. 

Cannibalism in walleye reared in tanks can be greatly 

affected by environmental conditions. High cannibalism 

rates have been directly related to population density 

(Polis 1981; Li and Mathias 1982; Malison and Held 

1992). In one study (unpublished data), we found that 

losses due to cannibalism increased as stoclung 

densities were increased from 1 to 5 fish/L. Because of 

differential losses due to starvation, however, overall 

habituation success was not different between 1 and 3 

fish/L. In fry, Loadman et al. (1989) suggested that the 

pattern of water flow was an important factor in 

reducing cannibalism in walleye by reducing frontal or 

lateral encounters. Similarly, using fry, Bristow and 

Summerfelt (1 994) suggested that turbidity decreased 

cannibalism by reducing the number of cohort encounters. In general, procedures that limit potentially 

cannibalistic encounters may prove beneficial to 

culturists habituating walleye fingerlings. 

NCRAC Culture Series 101 - Walleye Culture Manual 201 
Many of the losses during the habituation period that 

are attributed to disease can often be traced to stress 

incurred during harvest, transportation, or routine 

husbandry (Hussain and Summerfelt 1991). The most 

prevalent diseases occurring during the habituation 

process are myxobacterial infections, particularly those 

due to Flexibacter columnaris. Adhtionally, fin rot, 

furunculosis, bacterial gill disease and fungal infections 

have all been reported (Hnath 1975; Nagel 1976). 

“White tail syndrome”, an apparent response to severe 

stress at harvest, has also been observed by ourselves 

and others (A. Kaas, Wisconsin Department of Natural 

Resources, personal communication). To date, we are 

not aware of any studes documenting the clinical 

pathology of this usually fatal condition. 

Sub-optimal environmental conditions, particularly high 

water temperature and low flushing rate, have also been 

blamed for increased incidences of hsease. To reduce 

hsease problems, Nickum (1986) recommended high 

water quality and rapid flush rates, along with minimal 

handling when water temperatures exceed 68°F (20°C). 

Nagel (1 976) suggested lowering water temperatures to 

the low 60s” F (approximately 15OC) after walleyes 

have been habituated to formulated feeds, in order to 

reduce disease problems. Growth rates will normally 

decline, however, at these lower temperatures. 

Prior to the recent increased level of regulation of the 

aquaculture industry by the U.S. Food and Drug 

Administration, a number of compounds were used to 

alleviate stress and prophylactically and therapeutically 

treat diseases in walleye fingerlings. The use of many of 

these compounds is no longer permitted. Accordingly, 

we suggest that the reader refer to the chapter in this 

manual that discusses diseases and chemotherapeutic 

use in walleye. We have found that hsease outbreaks 

can be minimized by the use of least-stress harvesting 

and husbandry procedures, combined with prophylactic 

static salt baths (0.7% for 4h) administered after 

unavoidable stressful procedures such as weighing and 

measuring. 

Many formulated dets have been tested to habituate 

walleye fingerlings, including the W series diets 

developed at the U.S. Fish and Wildlife Service 

laboratories, various salmon and trout starters, and 

Oregon moist pellets (see Kuipers and Summerfelt 

1994). The most important characteristics of a formulated diet used for habituation are its nutrient composition, palatability, and cost. To some extent, these 

characteristics are interrelated. Generally, most &ets 

that have been successfully used have contained 

relatively high percentages of protein (40-60%). 

Palatability can be affected by many characteristics 

includmg size and size uniformity, shape, taste and 

texture. Nagel (1985) attributed high rates of habituation (80-90%) in part to the palatability of the knll 

flake diet that was used. Unless excessive, the cost of a 

diet used to habituate walleyes may be relatively 

unimportant, given the small amount of feed used 

during tlvs interval. 

Feeding strategies employed to habituate walleye 

fingerlings can have a significant impact on habituation. 

In this regard, many variables such as feeding frequency, rate, and method of feeding have been examined. Beyerle (1975) expressed a preference for 

automatic feeders, citing their inherent ability to feed 

on a 24-h basis and lack of the disturbance caused by 

hand-feeding. Nickum (1 986) recommended an initial 

feeding rate of 10% body weight daily. Nickum (1978) 

suggested that, since frequent hand feeding is often not 

practical or possible, automatic feeders may be virtually 

essential. He also suggested that feeders should supply 

small quantities of feed either continuously or at 

frequent intervals (e.g., every 5 min). Nagel (1976) used 

a combination of hand feeding and a clock-type feeder 

which “dispensed a few particles of feed continuously 

for 1-2 h” (Nagel 1974). Additional variables such as 

particle size, texture, and buoyancy have been tested, 

but to our knowledge few studies have been published 

to date. 

The interval during which pond-reared fingerlings are 

habituated is characterized by slow fish growth and 

poor feed conversion, both of which are due primarily 

to poor feed acceptance. Accordmgly, a short habituation interval should result in an overall improvement of 

fish growth and feed conversion. A short habituation 

interval also minimizes the extensive manpower needed 

during this period for fish husbandry, thereby reducing 

production costs (Malison and Held 1992). Whether the 

tandem pondtank method of producing feed-trained 

walleye fingerlings will prove to be cost effective when 

compare with other methods such as intensive fry 

culture or in-pond habituation remains open to question. 

Regardless of the production method used, however, a 

reliable and inexpensive supply of walleye fingerlings 

habituated to formulated feeds would greatly encourage 

202 NCRAC Culture Series 101- Walleye Culture Manual 
the development of a commercial industry producing 

food- size walleye. 

Acknowledgments 

we thank Thomas Kuczynski, Terence Barry, and 

Lynne Procarione of the UW-Madison Aquaculture 

Program for their invaluable assistance. Principal 

funding for the studies included in this chapter came 

from the North Central Regional Aquaculture Center 

with assistance from the University of Wisconsin Sea 

Grant College Program, National Oceanic and Atmospheric Administration, U.S, Department of Commerce, 

and the State of Wisconsin (Federal Grant NA90AA-DSF469, Project No. WAQ-22). 

Ref ere n ces 

Beyerle, G.B. 1975. Summary of attempts to raise 

walleye fry and fingerlings on artificial diets, with 

suggestions on needed research and procedures to 

be used in future tests. Progressive Fish-Culturist 

37: 1 03-1 05. 

Bristow, B.T., and R.C. Summerfelt. 1994. Performance 

of larval walleye cultured intensively in clear and 

turbid water. Journal of the World Aquaculture 

Society 25:454-464. 

Cheshire, W.F., and K.L. Steele. 1972. Hatchery rearing 

of walleyes using artificial food. Progressive FishCulturist 34:96-99. 

Colesante R.T., N.B. Youmans, and B. Ziolkoski. 1986. 

Intensive culture of walleye fry with live food and 

formulated diets. Progressive Fish-Culturist 48:33-37. 

Corazza, L., and J.G. Nickum. 1983. Rate of food 

passage through the gastrointestinal tract of fingerling walleye. Progressive Fish-Culturist 45:183. 

Cuff, W.R. 1977. Initiation and control of cannibalism in 

larval walleyes. Progressive Fish-Culturist 39:29-32. 

Dobie, J. 1956. Walleye pond management in Minnesota. Progressive Fish-Culturist 1851 -57. 

Hnath, J.G. 1975. A summary of fish diseases and 

treatments administered in a coolwater diet testing 

program. Progressive Fish-Culturist 37:106. 

Howey, R.G., G.L. Theis, and P.B., Haines. 1980. 

Intensive culture of walleye (Stizostedion vitreum). 

U.S. Fish and Wildlife Service Lamar Information 

Leaflet 80-05, Lamar, Pennsylvania. 

Hussain, M., and R.C. Summerfelt. 1991. The role of 

mechanical injury in an experimental transmission of 

f lexibacter columnaris to finger I i n g walleye. Jou r n al 

of the Iowa Academy of Science 98:93-98. 

Kuipers, K.L., and R.C. Summerfelt. 1994. Converting 

pond-reared walleye fingerlings to formulated feeds: 

effects of diet, temperature, and stocking density. 

Journal of Applied Aquaculture 4:31-57. 

Li, S., and J.A. Mathias. 1982. Causes of high mortality 

among cultured larval walleye. Transactions of the 

American Fisheries Society 11 1 :710-721, 

Loadman, N.L., G.E.E. Moodie, and J.A. Mathias. 1986. 

Significance of cannibalism in larval walleye 

(Stizostedion vitreum). Canadian Journal of Fisheries 

and Aquatic Sciences 43:613-618. 

Malison, J.A., and J.A. Held. 1992. Effects of fish size at 

harvest, initial stocking density and tank lighting 

conditions on the habituation of pond-reared yellow 

perch (Perca flavescens) to intensive culture conditions. Aquaculture 104: 67-88. 

Masterson, M.F., and D.L. Garling. 1986. Effect of feed 

color on feed acceptance and growth of walleye 

fingerlings. Progressive Fish-Culturist 48:306-309. 

Mclntyre, D.B., F.J. Ward, and G.M. Swanson. 1987. 

Factors affecting cannibalism by pond-reared juvenile 

walleyes. Progressive Fish-Culturist 49:264-269. 

Moore, A., M.A. Prange, R.C. Summerfelt, and R.P. 

Bushman. 1994. Evaluation of tank shape and a 

surface spray for intensive culture of larval walleyes 

fed formulated feed. Progressive Fish-Culturist 

56:lOO-110. 

Nagel, T.O. 1974. Rearing of walleye fingerlings in an 

intensive culture using Oregon moist pellets as an 

artificial diet. Progressive Fish-Culturist 3659. 

Nagel, T.O. 1976. Intensive culture of fingerling walleyes 

on formulated feeds. Progressive Fish-Culturist 

38:90-91. 

Nagel, T.O. 1978. Walleye production in controlled 

environments. Ohio Department of Natural Resources Division of Wildlife In-Service Note 386, 

London, Ohio. 

Nagel, T.O. 1985. Development of a domestic walleye 

broodstock. Progressive Fish-Culturist 47:121-122. 

Nickum, J.G. 1978. Intensive culture of walleyes: the 

state of the art. Pages 187-194 in R.L. Kendall, 

NCRAC Culture Series 101 - Walleye Culture Manual 203 
editor. Selected coolwater fishes of North America. 

Am e r i ca n Fish e ri es S oc i et y, Wash i n g to n , D. C . 

Nickum, J.G. 1986. Walleye. Pages 1 15-126 R.R. 

Stickney, editor. Culture of nonsalmonid freshwater 

fishes. CRC Press, Inc., Boca Raton, Florida. 

Polis, G.A. 1981. The evolution and dynamics of 

intraspecific predation. Annual Review of Ecological 

Systems 12:225-251. 

204 NCRAC Culture Series 101- Walleye Culture Manual 
Nagel, T. 1996. Intensive culture of fingerling walleye on formulated feeds. Pages 205-207 in R. C. 

Summerfelt, editor. Walleye culture manual. NCRAC Culture Series 101. North Central Regional 

Aquaculture Center Publications Office, Iowa State University, Ames. 

Intensive Culture Of Fingerling Walleye On 

Formulated Feeds 

Tim Nagel, London Fish HatcherH Ohio Department of Natural Resources, Division of Wildlife, London, Ohio 

43140 

Introduction 

This case study describes the tandem pond-tank culture 

a 6-in (152 mm) clear plastic cylinder (Figure 2). These 

water tight cylinders are secured to the bottom of the 

method for raising advanced fingerling walleye. These 

methods were developed at the London Fish Hatchery in the past 20 years. Pond-cultured fingerlings 

(1.5 in) are brought indoors where they are trained 

(habituated) to formulated feed then raised to 

finished size of about 6 in (152 mm). 

Methods 

P ond-culture 

Walleye culture ponds are typically filled in the third 

week in March. Ponds are stocked with 4-d-old 

posthatch at 100,00O/acre (4,047 ha) about the 

second week in April. The ponds are fertilized with 

alfalfa meal to promote and maintain phytoplankton 

and zooplankton blooms. When the zooplankton 

population declines, 1.5-in (38.1 -mm) walleye 

fingerlings (1,20O/lb, 545kg) are harvested. Harvest 

is done with care to minimize handling stress. The 

culture facilities at the London Hatchery are unique 

in that the ponds have been constructed to drain 

directly to a tank within the hatchery building where 

fingerlings can be harvested for stocking the rearing 

tanks. 

Tank-culture 

The excitable behavior of the fingerlings must be 

considered in design of the facilities used, or training 

walleye to formulated feed will not be successful. 

We have darkened the interiors of the 100-ft3 (2.8m’) 

rectangular troughs by covering them with Styrofoam 

to eliminate the stress of overhead light and shadows 

cast from movement in the hatchery (Figure 1). One 

opening is left in the cover to accommodate a 16-in 

(40.6 cm) clock-type feeder, The most significant 

technique factor in the success of the culture 

techniques is the use of submersed lighting. The 

troughs were illuminated with a low-intensity, 15 W 

incandescent bulb, located at mid-water depth inside 

concrete troughs with four brackets and lag screws 

Figure 1. Fish tank used at the London Fish Hatchery for 

training walleye fingerlings to formulated feed. The tanks are 

covered with Styrofoam to eliminate overhead light (the 

feeder is in the background). 

Figure 2. Prospective of homemade feeder that is mounted 

over a submersed light. Feed falls around the outside of the 

lighted cylinder. 

NCRAC Culture Series 101 - Walleye Culture Manual 205 
Chapter 8 - Habituating Pond-Reared Fingerlings to Formulated Feed 

(Figure 3). The feeder was located directly over the 

cylinder. Walleyes congregate around the feeders. The 

of disease. Although, decreasing the water temperature 

to the mid-60's"F (155°C) will reduce hsease probinternal lighting also reduced 

shadows and reflections from 

external sources. 

The optimal density for 

training pond-reared fingerlings to formulated feed is 

0.33 lb/ft3 (5.3 kg/m3) to 400 

fish/ft3 (1 1.3 fish/m3). To 

obtain this density, the lOO-ft' 

(2.83 m3) troughs are dwided 

with a central screen into two 

sections, and fingerlings are 

initially confined to only one 

(upper) of the two sections 

(Figure 4). A water flow rate 

of 20 gpm (75.7 Lpm) is 

used, which is equivalent to 

an exchange rate of 1.6/h. We 

consider an optimum water 

temperature for training 

fingerlings to be 68°F (20°C). 

Water temperature plays an 

extremely important role in 

this type of culture. Temperatures in the low 70's"F (21- 

23°C) will stimulate feeding 

Figure 3. Water tight acrylic cylinder used to 

house a submerged light. Brackets attach the 

cylinder to the tank bottom. 

lems, it also reduces growth rate 

by about one-third. 

The excitable behavior of the 

walleye is a factor which must be 

considered when scheduling 

cleaning or chemical treatments, 

because every disturbance causes 

stress and interrupts feeding, 

usually for several hours. On a 

normal feeding day, the troughs 

are cleaned or treated between 

1400 and 1600 hours, but fish are 

fed in the early morning and 

evening. 

Biotrainer , a hll-based &et, 

(Bioproducts, Inc., Warrenton, 

OR) is used as the starter diet. 

Initial feed sizes for 1.5 to 1.9 in 

(38 to 51 mm) fingerlings is 

number 3 and 4 crumbles. Initial 

feedng rates are 5% of their 

body weight/d. In this system 

with these conditions, feeding 

activity typically begins in less 

than 1-2 h after the tanks are 

walleye and promote rapid growth, however, temperature greater than 70°F (21.1 "C) may increase incidence 

stocked. A rapid habituation to formulated feed is 

important because when the fish become even slightly 

emaciated, cannibalism, tail-biting, and 

diseases will result in poor survival. Total 

mortalities are often less than 1 % of initial 

stocking density in the first two weeks and the 

fish will have doubled in weight. 

Figure 4. Culture tank with metal divider to crowd fish near feeder 

during the first 2 weeks of training. 

At two weeks, the fish are inventoried, graded 

to remove cannibals, and dip-treated prophylactically in a 500 ppm copper sulfate solution 

for 10 s as a prevention against columnaris, 

fin rot, and bacterial gill disease. If 

columnaris was detected, the trough is treated 

with 30 ppm copper sulfate for 1 min, then 

quickly flushed. Because the troughs have 8- 

in (203 mm) tilt-pipe drains, the troughs can 

be drained in less than 30 s. A short exposure 

time to 30 ppm copper sulfate is extremely 

important. Substantial mortalities will occur if 

206 NCRAC Culture Series 101- Walleye Culture Manual 
Habituating Pond-Reared Fingerlings to Formulated Feed - Chapter 8 

walleyes are subjected to this treatment for 2 min, and a 

34 min exposure will lull all fish. 

Table 1. Advanced fingerling production 

statistics. 

After 1 month, fingerlings average 2.5-in (63.5-mm) 

and weigh 21 O/lb (95.4kg). They are inventoried, 

graded, &p treated with copper sulfate, and the center 

screen removed. This doubles the trough volume and it 

reduces fish density to 0.50 lblft’ (8.0 kg/m3). The feed 

size and type are changed to 1.3-mm BioMoist Grower 

(Bioproducts, Inc. Warrenton, OR) and the daily 

feeding rate is reduced from S to 3% of total fish 

weight. 

After about 2 months fish have grown to 4-in (101.6 

mm) and SS/b (25kg). The feed size and type will be 

changed accordingly and the feed switched to 4.0 mm 

BioDry 3500 at a feeding rate of 2%/d. At this time, the 

internal lighting and clock-type feeders are removed 

and mohfied trough covers are used to accommodate 

12 ft (3.66 m) long solenoid-type feeders (Figure 5). 

The fingerlings are now at a density of 1 .0 lb/ft3 (1 6.1 

kg/m3)). Water flow is increased to 30 gpm (1 13.55 

Lpm). 

At the end of 90-100 d growing season, the walleye 

will be about 6 in (152.4 mm) and 20Ab (9.lkg). The 

densities in the troughs will be 2.0 lb/ft3 (32.1 kg/m3) 

with a 40 gpm (1 5 1.4 Lpm) flow rate. 

The survival rate for the intensive culture phase is about 

English Metric 

Feed conversion 

Flow rateshrough 

cost 

Cost per fish 

Survival 

Number 

Weight 

Initial weight 

Final weight 

Final length 

1.12 

$1.20/lb 

$0.06 

90% 

31,506 

1,575 Ibs 

1 ,200/1 b 

20/lb 

6 in 

40 9Pm 

1.12 

151 Lpm 

$0.54/kg 

0.00 

90% 

31,560 

715 kg 

5451kg 

9.l/kg 

152 mm 

90% of the initial stock (Table 1). Although 90% is 

exceptional compared with most published reports, 

these results have been replicated several times. We 

think that the success of our procedures is related to 

both the design of the culture system and the use of 

London strain fingerlings, which are progeny of a 

domesticated stock. These fingerlings start feeding 

within 2 h, while progeny of wild fish may not commence feeding for 2 days. Compared with 90% survival 

for London strain fingerlings, the survival rates for wild 

strain progeny normally were only around 50%. 

Figure 5.Two months after fish are trained to formulated feed, 

a long, rectangular tank-feeder is used for the balance of the 

culture season. 

Progeny from domestic broodstock will start 

swimming on their side loolung up towards the 

feeder. Wild progeny do not exhibit this behavior. The fish that we culture in an intensive 

culture have about one-third of the ventral lobe 

of their caudal fin permanently removed by fin 

erosion. Even ten-year old broodstock still have 

this marlung. Fin clipping or tagging is not 

necessary with these fish. 

In conclusion, when a reliable and good quality 

of water is available, mass production of 

walleye 12-14 in (305-356 rnm) could be 

produced by the end of the second summer. 

Thus, it seems more practical to raise walleye to 

12-14 in (30.5-25.5 cm) than 6-8 in (152-203 

mm) yellow perch. 

NCRAC Culture Series 101 - Walleye Culture Manual 207 
Chapter 8 - Habituating Pond-Reared Fingerlings to Formulated Feed 

208 NCRAC Culture Series 101- Walleye Culture Manual 
Bristow, B. T. 1996. Extensive-intensive production of advance fingerling walleye at the Spirit Lake 

State Fish Hatchery. Pages 209-212 in R. C. Summerfelt, editor. The walleye culture manual. 

NCRAC Culture Series - North Central Regional Aquaculture Center Publications Office, lowa 

State University, Ames. 

Extensive-Intensive Production of 

Advance Fingerling Walleyes at 

the Spirit Lake State Fish Hatchery 

Brian T: Bristow, Department of Animal Ecologx lowa State University, Ames, lowa 5001 I 

Introduction 

Pond-raised walleye fingerlings have been trained to 

eat formulated feeds in raceways at Spirit Lake State 

Fish Hatchery, Spirit Lake, Iowa, for the past eight 

years. Insight from these experiences was incorporated 

into the current culture protocol of the Spirit Lake 

walleye program. During the 1993 and 1994 culture 

seasons, production-scale evaluations of diets for 

training pond-raised walleye to formulated feed and 

evaluations of walleye performance when provided 

several grow-out diets were conducted. For these 

evaluations we used a tandem culture protocol (pondto-tank) to produce 26,000-32,000 advanced fingerling 

walleyes, 5-7 in (127-178 mm), for stoclung Iowa 

waters. The culture period consisted of three intervals: a 

pond culture period, when fry were stocked into ponds 

(see Jorgensen, 1995) and cultured for about 50 d on 

natural food; a 30-d training period after the fish were 

brought into the hatchery; and a 60-d grow-out period, 

which entailed the remainder of the culture season 

(from about August 1 - October 1). Two to four 

training- and grow-out diets were evaluated each year, 

and all but one of these diets were commercially 

available. This report describes the methods and 

equipment we used for culturing pond-reared walleyes 

on formulated feeds to an advanced size, and a brief 

summary of the results of the diet trials. 

Facilities and methods 

Wafer source 

Influent water from Spirit Lake gravity flows into a 

1 -acre pond, and is then pumped through a gravel filter 

into the hatchery. Pressurized oxygen was injected into 

the water between the settling pond and the hatchery at 

a rate of between 0.5 and 1 gpm (2-4 Wmin); the 

oxygen content of water flowing into the tanks was 

about 105% saturation. Water in the culture tanks was 

generally quite turbid (>lo NTU), and the fish were 

seldom visible. Water temperature was 70-75°F (21-24°C) 

for most of the culture season, 

but the mean temperature in 

1993 (70°F) was slightly lower 

than that in 1994 (73°F). 

Culture tanks 

Walleyes were cultured in 

twelve 1 56-ft3 (4.4 m3) concrete 

raceways that had light blue 

walls and floors (Figure 1). 

Water was supplied to each 

raceway at 20 gpm (76 L/min) 

for an exchange rate of about 

onceh. 

Figure 1. Fingerling culture raceways at the Spirit Lake State Fish Hatchery. 

NCRAC Culture Series 101 - Walleye Culture Manual 209 
Chapter 8 - Habituating Pond-Reared Fingerlings to Formulated Feed 

Lighting and feeding 

The culture room received natural lighting from nearby 

windows and skylights. Overhead florescent lights 

furnished lighting 24 h/d. In 1993, fingerlings were fed 

8% of their body weight/d throughout the entire 

experiment; in 1994, the initial feeding rate was 8%, but 

this rate was reduced to 6% when the fish were 5 in 

(127 mm) TL, and reduced to 4% on September 5 when 

water temperatures fell below 68°F (20°C). Feed was 

dispensed with automatic feeders every 5 min for 22.5 

h/d. The feeders were shut off from 0730 to 0900 hours 

during tank cleaning. Feeding rates were adjusted 

weekly in 1993 and daily in 1994 to compensate for 

changes in tank biomass from fish growth and mortality. As diet type and pellet size were adjusted for fish 

growth, mixing ratios of 25:75, 50:50, and 75:25 (new: 

current) were used, and each ratio was fed for 

2-3 d. Table 1 shows the pellet size used for various 

sized walleyes. 

Table 1. Pellet size of feed provided to 

various sized walleyes at the Spirit 

Lake State Fish Hatchery. 

Fish length Pellet size' 

(in) (mm) 

< 2.5 

2.5 to 3.5 

3.5 to 4.0 

4.0 to 4.5 

4.5 to 6.0 

1.0 (3) 

2.0 (4) 

2.5 (4 or %) 

3.0 (%2) 

3.5 (%) 

number/lb. The resulting value (230 fisldlb) was then 

used to calculate the appropriate weight of fish to stock 

into each raceway (28.25 lb, 12.8 kg). 

Following a 30-d training interval, the number of fish in 

each raceway was calculated, and the populations 

reduced to 0.18 lb/ft3 (2.9 gL); (2,500 fishhaceway) to 

begin the grow-out phase of the study (August 1 - 

September 15). 

1994. Pond-raised walleye fingerlings (45-d posthatch) 

were acquired from the Calamus Fish Hatchery, 

Burwell, NE on June 24. These fish had a mean length 

of 1.7 in (43 mm), and averaged 989 fish/lb (2,176kg). 

The fish were extremely emaciated with a mean Wr 

(Larscheid 1992) of 66.9. They were stocked into the 

culture tanks at a density of 0.04 lb/ft3 (0.64 gL); 

(5,900 fingerlings/ raceway). At the end of the 30-d 

training period, fish numbers were reduced to 2,689 

fisldraceway (0.25 lb/fP, 4.0 g/L) in preparation for the 

grow-out phase. 

Tank cleaning 

Feces and waste feed were flushed down the drain once 

daily by pulling the standpipe, increasing the water 

flow, and sweeping the tank bottom. During this 

process, the water level was lowered to about 5 in 

(12.7 cm), and the tank walls were sprayed with 

pressurized water to remove any accumulated fungus or 

feed residue. Additionally, the tank walls were scrubbed 

with a coarse brush about once each month. All dead 

fish were removed and enumerated daily and, when 

possible, the cause of death was recorded. 

Numbers in parenthesis represent standard feed sizes for 

crumbles or pellets. 

Fish source 

1993. Five-day-old walleye fry from Spirit Lake 

Hatchery were stocked into Welch Lake, a shallow 

natural lake near Spirit Lake. At 50-d posthatch (June 

30), the fingerlings were harvested: they averaged 2.4 in 

(61 mm) and 230 fisMb (506kg). The fish were in 

good condition with a mean relative weight (W,) 

(Larscheid 1992)' of 86.8. Fingerlings were stocked 

into raceways at a density of 0.2 lb/ft-? (3.2 g/L); (6,500 

fingerlings/raceway). Enumeration was done gravimetrically by weighing three 3-5 lb (1.4-2.3 kg) 

samples, counting the fish, and determining the mean 

Fish sampling 

Performance of fingerlings for the training and growout phases was evaluated using survival (%), growth, 

and feed conversion. Samples of 50 fingerlings were 

removed at 15-d intervals from each raceway and 

anesthetized in a 75 mg/L Finquel solution. Each fish 

was weighed to the nearest 0.0005 lb (0.2 g) and 

measured to the nearest 0.1 in (2.5 mm) and then 

returned to the tank. At the end of both the training and 

grow-out phases, lengths and weights were obtained 

from 100 fish sampled from each tank. All fish in each 

tank were weighed collectively at the end of the 

training interval, and populations were calculated by 

counting the number of fish in three 3-5 lb samples. At 

the end of the grow-out interval, all remaining fish were 

hand-counted. 

21 0 NCRAC Culture Series 101- Walleye Culture Manual 
Habituating Pond-Reared Fingerlings to Formulated Feed - Chapter 8 

Diets 

In 1993, three dets (Fry Feed Kyowa C-Series, Biodry 

1000, and Silver Cup Moist) were evaluated during the 

training interval. Four diets were evaluated during the 

grow-out interval. Two of the grow-out diets were 

closed formula commercial fish feeds (Biodry 1000 and 

Silver Cup Moist), and two were manufactured using 

the Walleye Grower 9015 open formula (Table 2) 

(developed by E T. Barrows of the US Fish and 

Wildlife Service Fish Technology Center, Bozeman, 

MT). The two walleye Grower 901 5 diets, however, 

were manufactured using dfferent techniques. One &et 

was formed into cylinhcal pellets under pressurized 

steam, and then crushed to create smaller particle sizes. 

For simplicity in this report, this form of the 9015 diet 

is referred to as “crumble.” The other diet was extruded 

into semi-round pellets of different sizes; this diet is 

referred to as “round.” The crumble diet was produced 

by Sterling H. Nelson and Sons Inc., Murray, UT. The 

round diet was manufactured at Kansas State University, Manhattan, KS. All diets were analyzed for 

protein, moisture, fat, and ash (Table 3). 

In 1994, two training dets (Fry Feed Kyowa and round 

extruded WG 9015) and three grow-out dets (crumble 

and round forms of WG 9015, and WG 9206, a newer 

Barrows formula in which anchovy meal replaced the 

more expensive herring meal) were evaluated. All but 

the Fry Feed Kyowa were manufactured by Sterling H. 

Nelson and Sons Inc., Murray, UT. 

Table 2. Composition of Walleye 

Grower 901 5. 

Ingredient Percent 

Herring meal 

Soybean meal 

Fish oil 

Wheat middlings 

Corn gluten 

Alfalfa 

Blood meal 

Lysine 

Methionine 

Binder 

Vitamin premix 

Choline 

Ascorbic acid 

Mineral premix 

44.44 

12.00 

10.61 

6.02 

8.30 

10.36 

4.1 8 

0.51 

0.35 

2.00 

0.60 

0.45 

0.1 5 

0.03 

chemically treated with either a l-h bath treatment of 

1% salt, or a l-h flow-through hp of 100 ppm Paracide 

F (formalin). For severe ich infections, an 

%hour, 40 ppm formalin drip treatment was used for 

about 10 consecutive d. 

Disease diagnosis and 

treatment 

Any time a moribund fish 

was observed during tank 

Table 3. Proximate analyses’ of the five diets evaluated at Spirit 

Lake State Fish Hatchery in 1993. 

cleaning, the gills were 

removed and observed 

microscopically. The only 

major increases in daily 

mortality attributed to 

disease were caused by 

parasite infestations. 

Chilodonella sp., ich 

(IC hthy op h th i rius rn u ltif li is), 

and Costia (Ichthyobodo sp.) 

were microscopically 

observed, occasionally in 

high numbers, on the gill 

tissues of moribund fish. 

These infestations were 

Diet 

Analysis Crumble Round Biodry SCM2 Kyowa2 

Protein 50.5 52.5 50.5 50.2 57.5 

Moisture 8.4 9.5 13.6 11.9 5.1 

Fat 16.0 12.2 18.8 16.3 13.5 

Ash 7.4 9.2 9.5 10.2 12.0 

Gross energy (K~al/g)~ 4.3 4.1 4.6 4.3 4.5 

Diet testing was conducted by Woodson-Tenent Laboratories, Inc., Des Moines, IA. 

* SCM represents Silver Cup Moist and Kyowa represents Fry Feed Kyowa C-Series. 

Calculated from proximate analyses using constant values for protein and fat from Piper et al. 

(1 982). 

NCRAC Culture Series 101 - Walleye Culture Manual 21 1 
Chapter 8 - Habituating Pond-Reared Fingerlings to Formulated Feed 

Resu Its 

7993 

During the training interval, survival and growth were 

significantly greater for fish fed Fry Feed Kyowa. 

Survival averaged 59.1 % in the six raceways fed Fry 

Feed Kyowa compared with 30.2 and 27.9% for those 

fed Biodry 1000 and Silver Cup soft moist, respectively. Over the grow-out phase, dfferences in survival, 

growth, and feed conversion among the feed treatments 

were not significant. However, in comparing only the 

two forms of WG-9015, fish fed the round pellet form 

had significantly less mortality than fish fed the 

crumble &et; possibly because the round pellet was 

similar in shape to the Kyowa training diet. Overall, 

mean density was 0.17 lbs/ft" (2.7 gL) and loading was 

1.3 lb/gal/min (0.156 kg/L/min) at the beginning of the 

grow-out interval, and density was 0.56 lbs/ft3 (9.0 g/L) 

and loading was 4.3 lb/gal/min (0.516 kg/l/min) at the 

conclusion of the grow-out interval. In 1993, the water 

temperature averaged 70°F (21"C), and the fish attained 

an average size of 5.1 in (130 mm) and 25.1 fishflb (55/ 

kg) with a mean W, of 96.3%. 

7994 

Fish trained on Fry Feed Kyowa again showed greater 

survival. Preliminary analyses of growth and feed 

conversion data indicate that these factors were not 

affected by diet type. It seems that fish trained on Fry 

Feed Kyowa and then switched to the round form of 

WG 9015 grew significantly faster than those raised 

exclusively on the round &et. In 1994, the water 

temperature averaged 73°F (22.8"C), and the fish 

attained a final mean size of 6.3 in (160 mm) and 13.7 

fish/lb (30.lkg) with a mean Wr of 99.8%. 

Conclusions 

Under the production protocol used in tlvs study, we 

recommend training pond-reared walleye fingerlings 

with Fry Feed Kyowa C-series and then converting 

them at about 30 d to a round diet with a formulation 

similar to those developed by Barrows (either 9015 or 

9206; Table 3). For 2-5 in walleyes, we fed 8% of their 

body weight in food/d, but when they are greater than 5 

in long (127 mm), 6% or slightly less may be a more 

efficient rate. We have developed general guidelines for 

estimating the amount of feed for fish of different initial 

sizes (Table 4), but the amount will vary with water 

temperatures. Further evaluations of optimal loadmg 

and density of fingerling walleyes would be beneficial, 

but two guidelines we have developed are: a loading 

index of 1.6 lb/gpm/in (0.08 kg/Lpm/cm), and a density 

index of 0.2 lb/ft3/in (1.26 kg/m3/cm). 

Table 4. Guidelines for estimating the 

amount (Ib/l000 fish) of walleye training 

and grow-out diets needed for raising 

pond-reared fingerlings from late June 

through late September. 

Pounds of feed/1000 fish 

of initial length of 

Feed size 

(mm) 1.5 in (38 mm) 2.5 in (64 mm) 

Training Diet 

1 .o 1.5 

2.0 4.0 

3.0 2.0 

0.5 

4.0 

5.0 

Grow-out diet 

2.0 5.0 2.0 

2.5 50.0 30.0 

3.0 100.0 120.0 

3.5 25.0 25.0 

Acknowledgments 

This study was conducted at the Spirit Lake State Fish 

Hatchery, Spirit Lake, Iowa, and funQng was provided 

by the Federal Aid in Sportfish Restoration Program 

(project F-l51-R), Iowa Department of Natural 

Resources, and Iowa State University. Assistance with 

the culture of the fish was provided by Wally Jorgensen 

and the staff of the Spirit Lake State Fish Hatchery. 

References 

Jorgensen, W. D. 1996. Extensive lake culture of walleye 

fingerlings. Pages 151-152 in R. C. Summerfelt, 

editor. Walleye culture manual, NCRAC Culture 

Series 101, North Central Regional Aquaculture 

Center Publications Office, Iowa State University, 

Ames. 

Larscheid, J. G. 1992. Natural lakes investigations. Iowa 

Department of Natural Resources, Federal Aid in 

Sportfish Restoration, Project 

F-135-R2, Annual Report, Des Moines. 

21 2 NCRAC Culture Series 101- Walleye Culture Manual 
Flowers, D. D. 1996. Intensive walleye culture in Ontario: advanced fingerling production methods. 

Pages 213-214 in R. C. Summerfelt, editor. Walleye culture manual. NCRAC Culture Series 

101, North Central Regional Aquaculture Center Publications Office, Iowa State University, 

Ames. 

Intensive Walleye Culture In Ontario: 

Advanced Fingerling Production Methods 

David D. Flowers, Ontario Ministry Of Natural Resources, White Lake Fish Culture Station, RR2 Sharbot Lake, 

Ontario, CANADA, KOH 2P0 

Introduction 

In Ontario, over 3.6 billion walleye have been stocked 

in Ontario waters since 1904, mostly newly-hatched fry. 

Stocking activity peaked in the 1940’s and 1950’s when 

117 million walleye (largely eggs and fry) were stocked 

each year. From 1974-1991, inclusive, an estimated 

156 million were stocked, 93% of the total were eggs 

and fry, fingerlings contributed only 6.5%. During the 

1960’s pond and fingerling research at White Lake Fish 

Culture Station, hereafter referred to as White Lake, 

paved the way for culture methods now in use in the 

Province. White Lake is the only government hatchery 

in Ontario presently raising walleye, however, in 1982, 

Ontario initiated a Community Fisheries Involvement 

Program (CFIP) which furthered the development of 

many partnerships with local associations. Many of 

these groups have produced fry and pond fingerlings for 

local stochng programs and it is through their efforts 

that most stocking in the Province is presently accomplished. 

0 bject ive 

This report describes methods for culturing advanced 

fingerlings based on experiences at White Lake. 

Considerable research and experimentation has been 

conducted at this facility aimed at developing practical 

methods for producing pond fingerlings and also larger 

advanced fingerlings. In the past 3 years over 100,000 

advanced fingerlings have been produced here, mean 

survival during intensive culture has been 50-60%. 

Good survival and consistent production of large 

fingerlings at White Lake has been dependent upon the 

quality (size and health) of pond fingerlings used for 

intensive culture. Culture success also depends on good 

fingerling habituation to formulated bets, following 

proven culture methods and maintaining a diligent 

monitoring program. 

Production methods 

At White Lake, walleye fry are extensively cultured in 

ponds for 4-8 weeks until they are about 1.4-2.4 in 

(40-60 mm). At this size they are harvested with seines 

and either stocked in local lakes or brought indoors for 

habituation to formulated hets. Intensive culture lasts 

10-1 2 weeks and results in the production of 4 in 

(10.2 cm) fingerlings that average 45/lb (99/kg). 

Culture environment 

Engerlings harvested from ponds are placed in tanks 

and held for 24 hrs before they are transferred to 

production units. This allows for easier removal of 

weak and moribund fish, aquatic insects, tadpoles, algae 

and organic debris. We select similar-sized fish for each 

production unit and cull large cannibals. Within 48-h 

after transfer to production units, the fish are given a 

lhr static bath of DiquatTM (10 mg/L, Diquat 

dibromide) and salt (sodium chloride at 1 %). This helps 

combat columnaris outbreaks attributed to the bacterium Flexibacter columnaris. 

The production units are cone shaped, 141 ft3 (4,000 L) 

fiberglass tanks that are approximately 6.6 ft (2 m) 

across and 6.6 ft (2 m) deep. They are initially filled to 

half volume and each is stocked at 0.19 Ib/ft3 (3.0 gL) 

with 1.5 inch (38 mm, 0.5-1.0 g) fingerlings. Water 

volumes are increased as walleye grow and no further 

handling or density reductions are needed. Higher 

starting densities are used to promote better feed 

acceptance, but thinning may be required. We monitor 

oxygen levels daily, and increase tank volumes, flow 

rates or reduce walleye numbers if oxygen falls below 4 

ppm. Larger walleye seem to crowd better than small 

ones and as a guideline, when fingerlings are approaching 4 in, we keep fish densities below 0.94 lb/ft3 (15 g/ 

L) at 68°F (20°C). 

The water source for all facilities at White Lake is from 

a natural mesotrophic lake. Blended surface and 

NCRAC Culture Series 101 - Walleye Culture Manual 21 3 
Chapter 8 - Habituating Pond-Reared Fingerlings to Formulated Feed 

hypolimnion water is used during intensive culture and 

temperatures are maintained between 68-72°F (20- 

22°C) for optimum growth of fingerlings. Flow rates to 

individual units are between 1 and 2 exchanges per hour 

which keeps oxygen levels above 4 ppm. We attempt to 

minimize stress by reducing activity and lighting 

around rearing units; low lighting (10-20 lux-measured 

at the surface) is provided 24 hrs/d. 

Feeding and nutrition 

when fingerlings are transferred from ponds to 

intensive culture units it is important that inventories 

and fish measurements are accurate. Loadmg densities 

and feeding rates will affect training success to formulated diets. Fingerlings are left alone for the first 72 hrs 

and not handled, except for routine feeding and 

maintenance. Automatic feeders are used and are 

checked throughout the day to make sure feed is 

available around the clock. It has been our experience 

that early feed acceptance is crucial to prevent starvation and cannibalistic behavior. 

One of the keys to successful habituation of pond-raised 

walleye to formulated diets is to use high quality 

“starter” feeds. We have had our best success with Fry 

Feed Kyowa type C diet (Biokyowa Inc., Chesterfield, 

MO). FFK is fed exclusively for 2 weeks before fish are 

fed a 1.5 mm standard trout production diet (MNR 89s) 

developed by Ontario Ministry of Natural Resources for 

final grow-out. Early in the training period, all fingerlings are fed only FFKC 1000 (1 mm) and C 2000 (2 

mm). During week 3, FFKC is fed in decreasing 

amounts while the MNR production diet is introduced 

in increasing quantities. The habituation period from 

FFKC to the lower-priced MNR diets lasts for approximately 1 week with final transition to trout diets by the 

end of week 3. 

For best training success and least amount of cannibalism we prefer to start with pond fingerlings larger than 

908/lb (2,OOOkg). Walleye as small as 2270/1b (5,000/ 

kg) at 4 weeks, have accepted dry dets but larger 

fingerlings seem to train easier with fewer mortalities. 

We have successfully trained pond fingerlings as large 

as 227/1b (500kg). 

Inappropriately sized feed can lead to poor training 

success. We found that FFKC 2000 (2mm) is too large 

as an initial feed for small pond fingerlings. For fish 

smaller than 908/lb 2,00O/kg) we start with FFK-C 

1000 (1 mm); and with fingerlings 454-908/1b (1,000- 

2,00O/kg) we feed a 50:50 blend of FFKC 1000 (1mm) 

and C 2000 (2mm). We use automatic feeders that 

dispense feed every 15 min, 20 hrs/d. Fish are fed at 

12% body weight/day for the first week, but ths is 

reduced by 2%/week for 3 weeks. Feedmg rates are 

maintained at 4-6% body weight/d during late August 

and early September or until water temperatures drop 

below 64°F (1 8°C). 

Disease treatments and routine monitoring 

Chemical treatments are essential during the first 4 

weeks of intensive culture to control columnaris 

disease. We use DiquatTM at 10 mg/L (1 h bath) for 3 

consecutive d each week. These preventative treatments 

reduce the risk of acute losses and help maintain fish 

health, consistent growth and predictable survival rates. 

If columnaris becomes well established it is often 

necessary to give the fish a 1 % salt bath concurrent with 

the first diquat treatment of the week. The salt seems to 

facilitate treatment effectiveness. 

To maintain proper water quality and prevent disease, 

tanks are cleaned at least once daily and mortalities are 

removed each morning and counted. Record keeping is 

a priority for all our programs, we monitor water 

quality, feeding rates, fish mortality, fish behavior and 

growth. 

Conclusion 

At White LAC, intensive culture methodology 

continues to be refined and improved with every 

production year. The tandem pond culture and intensive 

culture sequence has proven to be the most reliable and 

economical way of producing large numbers of 

advanced walleye fingerlings at White Lake. About 

40,000 advanced fingerlings were produced at this 

facility in 1992. These fingerlings were initially reared 

in ponds and then intensively reared to the fall at a cost 

of 27 cents (CDN) each (this includes labor, feed, 

chemical treatment and initial pond-rearing costs). The 

production cost for pond-reared fingerlings was 3.4 

cents (CDN) (based on annual production of 200,000 

summer fingerlings from 10 small ponds with a total 

surface area of 2.6 acres (0.96 ha). 

21 4 NCRAC Culture Series 101- Walleye Culture Manual