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CONTROLLED FRY AND FINGERLING PRODUCTION IN HATCHERIES

Harry Westers

Michigan Department of Natural Resources,
Lansing, Michigan 48909, USA

ABSTRACT

A case favoring the intensive flow-through rearing method over the extensive pond rearing method for the controlled production of fry and fingerlings is presented. Criteria considered are water consumption and various fish culture management practices, but economic implications are not discussed. Design and biological principles of the intensive rearing method are identified and explained.

A method for the successful intensive production of the hybrid tiger muskellunge (male northern pike (Esox lucius) × female muskellunge (Esox masquinongy)) is described.

Various problem areas are identified that require basic and applied research to permit progress in intensive production of species traditionally reared extensively.

RESUME

L'alevinage à l'intensif en eau courante, du point de vue de la quantité d'eau necessaire et plusieurs autres facteurs piscicoles est favorable en comparaison avec d'alevinage à l'extensif en eau stagnante. Les principes biologiques et les caractères et techniques des methodes d'alevinage intensif sont identifiées et expliquées.

Est décrite une méthode pour l'alevinage à l'intensif du tiger muskellunge hybride (male brochet (Esox lucius) + femelle muskellunge (Esox masquinongy)). Des plusieurs problèmes sont identifiés, qui necessitent des recherches fondamentales et appliquées afin d'avancer la production en intensive des espèces traditionellement élevées en extensive.

1. INTRODUCTION

The production of fish in flow-through rearing systems offers controls not available in static pond rearing. Within each of these two methods, intensive and extensive, there are many variants and degrees of production intensity (Figure 1).

The intensive method is considered superior for the mass production of fry and fingerlings. Not only can the rearing environment be controlled, but hatchery management practices can also be conducted with much greater efficiency and accuracy.

Although the flow-through, highly intensive method appears to be quite consumptive of water, it shall be shown that water demands may actually be less than they are with extensive production methods.

One fact which is very noticeable in intensive rearing is the rapidly increasing demand for water once fingerlings reach a size of about 10 centimeters (Figure 2). This concept is also presented in Table I, by showing the decline in numbers of fish that can be produced on a fixed water supply as they increase in size.

From these examples it becomes obvious that mass production of fry and small fingerlings has excellent possibilities in intensive, flow-through rearing systems. This, of course, has been recognized for a long time and the method has been used for trout and salmon already for some two hundred years (Slack, 1872). However, not until about a decade ago, have serious and coordinated attempts been made to apply this technique to species of fish which have been traditionally reared extensively: largemouth bass (Micropterus salmoides), Snow (1968); esocids, Graff and Sorensen (1970); walleye (Stizostedion vitreum vitreum), Cheshire and Steele (1972); channel catfish (Ictalurus punctatus), Stickney et. al. (1972); striped bass (Morone saxatilis), Rhodes and Merriner (1973); and yellow perch (Perca flavescens), Stuiber (1975). Successes have varied greatly with species.

This paper discusses the principles of the intensive rearing method in flow-through systems; the production of a piscivorous fish in an intensive flow-through rearing system; and the present state of the art of the intensive production of fish traditionally reared extensively.

2. BASIC PRINCIPLES

2.1 Hydraulics

Intensive fish production in flow-through rearing systems operates on the following basic principles:

  1. The inflowing water delivers the needed oxygen
  2. The inflowing water continuously replaces the “used up” water
  3. The outflowing water continuously removes the metabolic wastes
  4. The outflowing water verifies the safe loadings (dissolved oxygen and ammonia levels).

The principle is to maintain the quality of the water at an acceptable level from the moment it enters the unit until it leaves it. If the exchange rate is 400% per hour, each water particle should stay exactly fifteen minutes in the container. As the water travels from the intake to the outlet, oxygen is removed and metabolites are added. Once arrived at the foot, it should have been fully utilized and of the predetermined, minimal quality with respect to dissolved oxygen and ammonia levels, and whatever other parameter may be selected. The water is then either disposed of or reconstituted for a second use.

Although these are rather logical principles, they are difficult to attain unless there is both proper design and mode of operation. They are best accomplished by having the water both enter and leave the rearing unit across its full width. Short-circuiting and stagnation of the water must be kept at a minimum. These objectives are best realized with longitudinal, rectangular rearing containers with a width to length ratio of approximately one to ten (1:10), as discussed by Westers and Pratt (1977).

2.2 Water quantity

The rearing environment is best controlled if the production unit is operated with relatively high exchange rates. Changeover rates of 400% per hour have been recommended by Westers and Pratt (1977). This will result in sufficient inertia to avoid any significant short-circuiting or stagnation, provided there is proper design of the rearing unit. That high flows do not result in greater water consumption per unit production is shown when the intensive and the extensive method are compared in terms of water consumption per unit of fish produced.

In Table II this comparison is made for the production of hybrid tiger muskellunge (Esox masquinongy)) and in Table III it is made for the production of walleye fingerlings.

The above examples represent the production of piscivorous fish species, which quickly turn to cannibalism once food supplies are low. The data of tiger musky production is representative for the situation in Michigan, U.S.A. When intensively cultured, they are fed a pelletized artificial dry diet, while in extensive culture, the fish are supplied natural food only.

For the extensive rearing of walleye fingerlings, data of Dobie (1966) is used, while the values for intensive rearing are theoretical (Table III).

The differences in water consumption between the intensive and extensive method narrows as the fingerlings grow larger. However, it is important to consider two factors in the water consumption comparison, which were not applied to the values presented in Tables II and III. First, there is the difference in mortality pattern between intensive and extensive rearing of piscivorous species. not only are the initial mortalities much higher in extensive rearing, but they continue to be higher throughout the entire rearing period. This is related to the fact that cannibalism is very difficult to control in extensive rearing ponds. It is necessary therefore to start with a higher number of fry to produce a specific number of fingerlings, with the extensive method than with the intensive method.

The second factor to be considered is the design of the intensive production facility. With proper design and water quality, the water can be used three times, with solid removal and reaeration as the only water reconditioning measure between each use (Westers and Pratt, 1977). This technique was tested with tiger muskellunge and brown trout (Salmo trutta) with good success by Pecor (1977) and Hartman (1977) respectively.

In Table IV and Figure 3, the water consumption rates of three intensive rearing situations (numbers equal those of extensive rearing, A; single pass use, B; three-pass use, C.) are compared with the extensive rearing method.

Although the values do not represent actual data, they are sufficiently realistic to make a valid comparison of water consumption between two basic rearing methods, intensive and extensive, for the production of 3 000 piscivorous fingerlings up to 20 cm.

Production throughout the 175-day rearing period is expressed in numbers (columns 3 and 4) and in kg per ha (column 6) and for intensive rearing in kg per 1 per min flow (column 8). The total water consumption is expressed in m3 (columns 9 through 12).

Figure 3 illustrates the differences graphically. Curve A represents the situation where intensive production numbers are equal to those during the extensive rearing phases (Table IV, column 3). Water consumption equals out after 100 days rearing at a fingerling size of 13 cm. But as stated earlier, this comparison is not too valid since mortality patterns do differ considerably between extensive and intensive rearing throughout the cycle.

Curve B reflects the difference in mortality between extensive and intensive rearing (see also Table IV, column 4). The water is used only once. In this case the water consumption rate equalizes after about 150 days of rearing and at a fingerling size of approximately 17 cm.

Finally, Curve C represents the three-pass intensive rearing approach, with the same mortality pattern as Curve B. As noticed, the water demands for the production of 20 cm fingerlings is only 50 percent of the extensive method (6 000 m3 versus 12 000 m3).

From this example, it appears that, on the basis of water consumption, the intensive method is superior for the production of fingerling piscivorous fish. However, this is but one factor. Even more significant is the fact that the intensive method affords a much greater control in the production of fingerlings, resulting in more consistent (predictable) production levels. It also permits greater efficiency in hatchery management (feeding, disease control, inventories, growth rate data, mortality records, harvesting, water use, environmental controls, etc.) and resource utilization (fewer spawners).

For these reasons Michigan has vigorously pursued the development of intensive rearing techniques for piscivorous species. Major breakthroughs have been made in the culture of esocids and have been reported by Pecor (1978) and Graff (1978). With regards to walleyes, Nickum (1978) documented that important advances are still awaiting the mass production of intensively reared fry and fingerlings. Walleye rank very high in management needs of many states in the U.S.A.

Presently, extensive production of walleye fingerlings in Michigan takes place in rearing ponds scattered throughout the state. Average pond stocking rates per ha and the resulting fingerling production over the last 6 production years are shown in Table V.

Although an average production of 10 000 6.0 cm fingerlings per ha, as used in Table IV, has not been attained, individual ponds have produced up to 40 000 fingerlings of that size per ha. Variations in production are influenced by whether or not the pond is manageable (drainable versus undrainable), how intensively the pond itself is managed (fertilization and predator control), and by a complexity of interrelationships of climatic, soil and water characteristics.

2.3 Water quality

The mass production of fry and small fingerlings in hatcheries requires high quality water. It must be well exygenated, relatively free of impurities and of the right temperature range for the species produced. The best sources are well and spring water, although surface waters, rivers and lakes may meet the requirements. Sources free of fish populations are much preferred, allowing a greater control over the introduction of parasitic, bacterial and viral pathogens into the rearing environment. In Michigan excellent successes have been experienced with well, spring and river sources for the intensive production of tiger muskellunge (Pecor, 1978).

Very little is known about the specific water quality requirements for the intensive production of those species traditionally reared extensively. It may be assumed however that waters showing a “natural range” in the various chemical parameters, uncontaminated with environmental pollutants and relatively low in suspended solids, should have excellent potential. Before such sources are developed however, bio-assays should be conducted under simulated rearing conditions in a pilot production facility.

3. PRODUCTION IN INTENSIVE REARING FACILITIES

3.1 Flow requirements

As was stated, intensive rearing in flow-through systems operates on the principle of delivering oxygen to the fish and removing metabolic waste.

If the oxygen consumption rates of the fish are known and the minimum allowable dissolved oxygen level in the effluent has been established, the minimum flow requirements, based on oxygen, can be determined.

The flow requirement is expressed in kg fish per liter per minute flow (kg/lpm) and is termed loading.

Metabolic rates of fish are often reported in mg of oxygen consumed per kg fish per hour (mg/kg/hr). Since 1 lpm flow of water delivers 60 mg of dissolved oxygen per hour for each mg/l dissolved oxygen, water which delivers 0in mg/l dissolved oxygen to a fish rearing unit and which must maintain a minimum level of 0out mg/l in the effluent, can support a metabolic level of (0in-0out) × 60 mg/kg/hr per each lpm.

On the basis that hatcheries have a design parameter of 90 percent saturation with dissolved oxygen for the incoming water, and that the minimum allowable effluent levels are 5.0, 4.0 and 3.0 mg/l for cold-, cool- and warmwater fish respectively, Table VI has been generated to indicate the metabolic rates (mg/hr) that can be supported per lpm flow. The selection of the minimum allowable levels in the effluent is somewhat arbitrary, although Smith and Piper (1975) recommend 5.0 mg/l for rainbow trout (Salmo gairdneri) and Huisman (1974) recommends 3.0 mg/l for the common carp (Cyprinus carpio).

The three major factors which routinely affect the metabolic rates in hatchery fish are water temperature, fish size, and feeding. Smith (1976) found the increase in metabolic rate linear with increased temperature. He tested small (1–4 g) fingerlings of rainbow trout, brook trout (Salvelinus fontinalis), lake trout (Salvelinus namaycush), and Atlantic salmon (Salmo salar) over a temperature range from 3 to 18°C.

A similar pattern is predicted by Smith (personal communication) for fingerlings of other species of fish within their normal temperature range. Oxygen consumption data collected by Elliott (1969) from chinook salmon fingerlings under hatchery conditions also support a straightline relationship between metabolic rates and temperature.

With regards to the effect of size on metabolic rates, he found that 6.0 cm fingerlings consumed 1.2 times as much oxygen as those 9.0 cm long and 1.5 times as much as 13.0 cm fingerlings. The measurements were taken while the fish displayed normal activity under hatchery conditions. Normal activity was defined as the state in which oxygen consumption is fairly stable and the fish, as a group, are in a relatively quiescent state.

Feeding (Smith, personal communication) gives an increase in metabolic rate from 1.5 ro 3.0 times the fasting level. Elliott (1969) found 1.5 to 2.0 times over the normal activity level. Marked declines in metabolic rates occur from one to five hours after feeding. Variations are due to feeding frequencies, levels, fish species, fish size, temperature, etc.

Data by Elliott (1969), Brett (1976) and Hartman (1977) indicate that metabolic rates during feeding are approximately twice as high as during the off-feed period. Under normal hatchery conditions, high metabolic rate (active metabolism) occurs during a 12 to 16 hour period which coincides with the feeding days plus an additional four hours after the last feeding.

Levels of such active metabolism for cold-, cool- and warmwater fish have been gleaned from the literature and are presented in Table VII, along with corresponding maximum loadings (kg fish/lpm).

Oxygen consumption rates at hatcheries are not routinely measured in mg/kg/hr. Therefore, in order to determine the maximum permissible loadings based on available oxygen to the fish, Westers (1978) proposed a loading equation which uses the grams of oxygen required to metabolize one kg of pelleted food under optimum feeding levels. He assumes that the fish maintain an active metabolic rate of a 16-hour day. The available oxygen per lpm during that period is 16 × 60 × (0in-0out) mg or 960 (0in-0out) mg. For all practical purposes, it can be assumed that the available oxygen equals (0in-0out) grams per 16-hour period. The suggested loading equation, which would cover the period of active metabolism (16 hrs) in the hatchery is:

Willoughby, et. al. (1972) and Hartman (1977) determined that, under conditions of optimum feeding levels, salmonids consume approximately 200 g of oxygen per kg food fed. Applying this value to the loading equation for an influent oxygen level of 10.0 mg/l, the following formulas are presented:

and
and, for a percent body weight (%B.W.)
feeding level of 4.0, we have:
or 0.63 kg/lpm, since (c), the loading expression, is the reciprocal of (b).

Tiger muskellunge showed an oxygen consumption of 110 g per kg food when fed a dry pelleted diet at optimum feeding levels over a 16-hour day (Pecor, 1979).

Huisman (1974) measured 210 g per kg food for carp fed a dry pelleted diet. He found that the oxygen consumed per unit of food was independent of fish size and water temperature. Pecor (1979) found that tiger muskellunge fingerlings maintained a constant oxygen consumption per unit of food independent of fish size. The temperature was not varied. Brett's (1976) data shows that yearling sockeye salmon (Oncorhynchus nerka) have a constant oxygen consumption per unit of food independent of temperature when fed at optimum levels. If indeed the oxygen consumption per unit of food fed remains constant, i.e. independent of fish size and water temperature, the loading equation proposed by Westers has validity, providing the feeding occurs at optimum levels, a normal practice at most hatcheries. The relationship of metabolic rates and percent body weight feeding levels against the constant oxygen consumption per unit of food is shown in Figure 4.

If the concept of a constant oxygen requirement per kg food is valid, it can be concluded that overfeeding will result in apparent lower values, underfeeding in apparent higher values. This is illustrated with Figure 5, where higher feeding levels are located to the left and lower levels to the right of the 110 and 200 oxygen consumption lines.

Although salmonids and carp have near identical loading equations (200 and 210), carp fingerlings need about twice the flow per kg fish as do salmonids, since carp, under conditions of relative comparable temperatures, require twice as much food. Under conditions of comparable size and rearing water temperatures, the metabolic rate of carp fingerlings is about twice that of salmonids.

Esocids' loadings (kg/lpm) approximately equal those of salmonids, when reared at comparable temperatures for these species, despite the fact that the esocid loading equation (110) is much more favorable in water requirements per unit of food. However, optimum feeding levels for esocids are twice those of salmonids. Since esocids seem to require only 55 percent of the oxygen to metabolize a kg of food as compared to salmonids and carp, it can be postulated that the standard metabolic rate of esocids is much lower - than those for salmonids and carp. At the same time, it may be hypothesized that these latter fish, since they show approximately the same oxygen consumption level per kg food, have standard metabolic rates which approximately equal those of salmonids.

Further studies should be conducted in this area.

3.2 Space requirements

To accomplish the hydraulic objectives in a flow-through rearing unit, Westers and Pratt (1977) recommend 4 water changes per hour. Provided there is proper design of the rearing container, this relatively high exchange rate prevents short-circuiting and stagnation.

The relationship between loading (kg/lpm) and density (kg/m3) with hourly exchange rate (R) as the only variable is expressed by Westers (1970) as:

Thus, a loading of 1.0 kg/lpm will result in a density of 16.7 kg/m3 per hourly exchange rate (R=1). With an exchange rate of 4 per hour (R=4), the density is 66.8 kg/m3.

Under these conditions, densities for fingerlings will seldom exceed 100 kg/m3 for salmonids, 50 kg/m3 for muskellunge and 50 kg/m3 for carp.

Yet, much higher densities have been attained without negative effects upon fish health, food conversion and growth rates. For instance Westers (1964) kept coho salmon (Oncorhynchus kisutch) fingerlings at over 300 kg/m3 at a corresponding loading of 0.6 kg/lpm; Murai (1979) maintained channel catfish fry at 467 kg/m3 at a loading of 0.32 kg/lpm; and Clary (1979) produced 5.0 cm rainbow trout fingerlings commercially at a density of 175 kg/m3; the loading was 0.33 kg/lpm. In Michigan, tiger muskellunge fingerlings were intensively reared at densities of 16, 32, 48 and 80 kg/m3 all at a loading of 1.45 kg/lpm. No difference could be demonstrated in growth rates, food conversions, mortalities (Pecor, 1979) and various physiological parameters (Hnath and Zischke, 1978).

An intensive rearing facility designed for a mode of operation of four water exchanges per hour is expected to have the capability to produce healthy fingerling fish in an efficient balance between loading (flow) and density (space) as shown in Figure 6.

4. CONTROLLED PRODUCTION OF A COOLWATER FISH IN AN INTENSIVE REARING FACILITY

During the last three years, some 100 000 tiger muskellunge fingerlings, ranging in size from 18 to 20 cm, have been produced annually in flow-through rearing systems in Michigan. Although the methods have been described in some detail by Pecor (1978), a brief account will be given of the 1977 production performance.

After the eggs were force-hatched with warm water, the fry were placed in throughs with a rearing volume of 300 l. Boiler-heated well water was supplied at a temperature of 20°C. Daily, 1-hour formalin treatments, at a concentration of 1:4000, were used to combat fungus infections. Despite this, a 12% mortality took place during the 9-day yolk absorption period, primarily attributed to fungus growth.

During the next phase, the training period, the fish were presented artificial food at 5-minute intervals by means of automatic feeders. It is important that the food is distributed over the entire surface since the muskellunge fingerlings will not pursue it. A poor food distribution pattern will greatly aggravate the problem of cannibalism. Even with good food coverage, cannibalism during this stage was quite prevalent. During most of the phase, the feeding fry cannibalized the nonfeeding fry especially as size differences grew more pronounced. The total losses during this 18-day period were 27%, of which 20% had to be attributed to cannibalism. During the last 7 days' rearing in the troughs, after the dying and weak fry were removed, only 1% additional mortality occurred.

Final production in the troughs reached a loading of .6 kg/lpm and a density of 26.7 kg/m3. Fingerlings had a length of 5.0 cm at the end of this rearing phase. They were then transferred to another hatchery and placed in indoor concrete rearing tanks with a water volume of 5.5 m3. They received boiler-heated spring water at a temperature of 18.5°C. Daily formalin treatments at a 1:4000 concentration for one hour were continued to control gill fungus. During the 26-day tank rearing phase, a columnaris outbreak claimed 6% over a 7-day period. The disease was brought under control with medicated food containing 4% Terramycin which was fed over 10 days at a 2% body weight level. Total mortality during the entire time (26 days) was 23 percent, but less than one-third of this could be accounted for, the rest was attributed to cannibalism.

At the termination of tank rearing the fish were 10.8 cm long. They were transferred to 2 outdoor raceways with a rearing volume of 50 m3. The water source was the Platte River, with fluctuating temperatures from 13 to 19°C. Outdoor rearing continued for 42 days, the fish grew to 18.5 cm and reached a maximum loading of 53 kg/lpm with a corresponding density of 30 kg/m3. Losses were 8.6%. The results are summarized in Table VIII.

The experience of several years with intensive production of esocids has led to the following recommendations:

  1. To control cannibalism:

    1. Provide for a 16-hour photo period and feed over the entire time.
    2. Distribute food over entire rearing water surface.
    3. Feed frequently, starting at 5-minute intervals with fry, 10-minutes with 10 cm fingerlings and 15-minute with fingerlings 15 cm and larger
    4. Remove obvious cannibals.

  2. To maximyze growth rates:

    1. Establish the % body weight feeding level with a hatchery constant of 100 for a temperature of 20°C according to Pecor (1978).
    2. Use automatic feeders to avoid people activity and to permit frequent feedings.
    3. Maintain a temperature from 18 to 20°C.

  3. To control diseases:

    1. Fungus infections: use prophylactic treatment with formalin at 1:4000 for 1 hour daily for fingerlings up to 10.0 cm in length, every other day for larger fish, administered under constant flow.
    2. Bacterial gill disease: daily treatment for 4 consecutive days with Hyamine 3500 at 2 mg/1 active ingredient under constant flow.
    3. Columnaris: medicated food containing 4% Terramycin fed at 2% body weight for a 10-day period.

  4. To maintain a quality rearing environment:

    1. Use “clean” water, low in suspended solids.
    2. Maintain the dissolved oxygen level in the effluent at or above 4.0 mg/1.
    3. Operate at 4 water changes per hour.
    4. Make flow-through rearing containers self-cleaning with baffles as recommended by Westers and Pratt (1977) and remove solids twice daily during the indoor rearing phases.

5. THE CURRENT STATE OF THE ART

The successes accomplished with the tiger muskellunge have come about through coordinated efforts by various state fisheries agencies and the United States Fish and Wildlife Service (Graff, 1978). This group is continuing the search for better diets and improved rearing techniques, not only for esocids, but even more so for walleyes. Despite all the efforts that have gone into developing intensive walleye culture techniques no major breakthroughs have occurred, yet enough has been learned to expect success (Nickum, 1978).

For instance, it has been clearly demonstrated that some of the walleye fry will accept dry diets under intensive rearing conditions. The acceptance of an artificial diet constitutes a key factor in the success of intensive culture. Without it intensive hatchery production cannot be practiceable.

There are 2 aspects to the successful application of artificial diets in intensive culture. It must be palatable and nutritionally complete. The first involves proper particle size, texture, taste and/or odor, but it must also meet the behavioral peculiarities of the fish, which could involve one or more of the following: color, shape, floating or sinking, rate of sinking, movement while sinking, etc. As for nutrition, a coordinated federal diet testing program for coolwater fish started in 1971 with 3 formulations designated W-1, W-2 and W-3, culminating in 1974 with the W-7 formulation, a high protein, high energy diet, Table IX.

The W-7 diet is now routinely used on a production basis for the rearing of tiger muskellunge. Although many apparently healthy fingerlings have been produced with this diet, their ability to survive well in fish management applications has not yet been fully established. Evaluations are being conducted in Michigan. In a recent study a number of physiological parameters were compared between intensively and extensively (natural diet) reared tiger muskellunge fingerlings (Hnath and Zischke, 1978). The average values are presented in Table X. Interpretation is difficult. The green livers may well be diet associated since intensively reared fish lost their green livers after they were placed in an extensive rearing pond on natural food. The leucocrit values are puzzling. Extensively reared fish show much lower values. In studies conducted by McLaey and Gordon (1977), in salmon and trout, depressed leucocrit values are associated with stress. It seems unlikely that extensively reared fish are under greater stress than intensively reared fingerlings. Further studies should be conducted. The data on glucose represents only few data points, but in one instance, the intensively reared fish showed a 3-fold level over the pond fish. This may be an indication that carbohydrates are a problem for esocids. Again, further research into this matter is most desirable.

As for walleyes, the most pressing need is an acceptable diet (palatable and nutritional) for the fry. Although some of the fry, in various trials, have ingested artificial food, survival, over a 2 to 3 week period, has consistently dwindled to zero, most likely due to malnutrition.

The most promising feeds for these extremely small fry appear to be the micro-encapsulated feed capsules which do not leach out their nutrients after contact with water. Unfortunately this technique has not yet been fully developed on a commercial scale (Jones, personal communication, 1978).

Another potential food source is the single-cell protein sources from specific yeast or bacteria. Appelbaum and Dor (1978) have successfully fed carp fry for 10 days with the yeast Candida lipolytica.

Resolving the many problems for these fish will, no doubt, expedite progress with other important species. Not only must the diet problem be resolved, but intensive culture demands also that the physiological, physical and ethological requirements of the fish are met in the design and operational modes of the production facility (Westers, 1978).

A concerted, coordinated effort by many investigators is, of course, the fastest way to make the desired progress.

6. REFERENCES

Appelbaum, S. and U. Dor, 1978 Ten day experimental nursing of carp (Cyprinus carpio L.) larvae with dry feed. Bamidgeh. 29 (3): 85–88.

Brett, J.R., 1976 Feeding metabolic rates of young sockeye salmon (Oncorhynchus nerka), in relation to ration level and temperature. Fisheries and Marine Service. Techn. Rep. 675. Environment Canada: 43.

Cheshire, W.F. and K.L. Steele, 1972 Hatchery rearing of walleyes using artificial food. Prog. Fish. Cult. 34 (2): 96–99.

Clary, J.R., 1979 High density trout culture. Salmonid. 3 (1): 8 – 9.

Dobie, J., 1966 Esperiments in the fertilization of Minnesota fish rearing ponds. Proc. of the World Symp. on warm-water pond fish culture. FAO Fish. Rep. No. 44(3): 274 – 284.

Elliott, J.W., 1969 The oxygen requirements of chinook salmon. Prog. Fish. Cult. 31 (2): 67 – 73.

Graff, D.R., 1978 Intensive culture of esocids: The current state of the art. Selected Coolwater Fishes of North America, ed. R.L. Kendall. Spec. Publ. No. 11. Am. Fish. Soc.: 195 – 201.

Graff, D.R. and L. Sorenson, 1970 The successful feeding of a dry diet to esocids. Prog.Fish.Cult. 32 (1): 31 – 35.

Hartman, J., 1977 Ammonia production and oxygen consumption of brown trout (Salmo trutta fario) in a three pass serial reuse system. Mich. Dept. of Nat. Res. (Unpublished).

Hnath, J.G. and J. Zischke, 1978 A partial report on a fish culture development project for 1978 with esocids (tiger muskies) at Wolf Lake Hatchery. Mich. Dept. of Nat. Res. (Unpublished)

Huisman, E.A., 1974 Optimalisering van de groei bij de karper (Cyprinus carpio L.) Een op de visteelt gericht onderzoek. OVB Utrecht, The Netherlands: 95 pp.

McClay, W., 1979 Walleye production summary. Mich. Dep. Nat. Res. (Unpublished)

Mclaey, D.J. and M.R. Gordon, 1977 Leucocrit: a simple hematilogical technique for measuring acute stress in salmonid fish, including stressful concentrations of pulpmill effluent. J. Fish. Res. Bd. Can. 34: 2164 – 2175.

Murai, T., 1979 High-density rearing of channel catfish fry in shallow troughs. Prog. Fish. Cult. 41 (2): 57.

Nickum, J.G., 1978 Intensive Culture of Walleyes: The state of the art. Selected coolwater fishes of North America, ed. R.L. Kendall. Spec. Publ. No. 11. Am. Fish. Soc.: 187 – 194.

Pecor, C.H., 1977 Experimental intensive culture of tiger muskellung in a water reuse system. Prog. Fish. Cult. (Accepted for publication).

Pecor, C.H., 1978 Intensive culture of tiger muskellunge in Michigan during 1976 and 1977. Selected Coolwater Fishes of North America, ed. R.L. Kendall. Spec. Publ. No. 11: 202 – 209.

Pecor, C.H., 1979 The effects of rearing density on intensively reared tiger muskellunge fingerlings. Mich. Dept. of Nat. Res. (Unpublished).

Rhodes, W. and J.V. Merriner, 1973 A preliminary report on closed system rearing of striped bass sac fry to fingerling size. Prog. Fish. Cult. 35 (4): 199 – 201.

Slack, J.H., 1872 Practical trout culture. New York: The American News Company: 143 pp.

Smith, C.E. and R.G. Piper, 1975 Lesions associated with chronic exposure to ammonia. The pathology of fishes. W.E. Ribel and G. Migaki, eds. Univ. of Wis. Press.: 497 – 514.

Snow, J.R., 1968 The Oregon moist pellet as a diet for largemouth bass. Prog. Fish Cult. 30 (4): 235.

Stickney, R.R., T. Murai and G.O. Gibbons, 1972 Rearing channel catfish fingerlings under intensive culture conditions. Prog. Fish Cult. 34 (2): 100 – 102.

Stuiber, 1975 No reference given.

Westers, H., 1964 A density and feeding study with coho salmon. Mich. Dep. Nat. Res. (Unpublished)

Westers, H., 1970 Carrying capacities of salmonid hatcheries. Prog. Fish. Cult. 32 (1): 43 – 46.

Westers, H., 1978 Biological considerations in hatchery design for coolwater fishes. Selected coolwater fishes of North America, R.L. Kendall, ed. Spec. Publ. No. 11. Am. Fish. Soc.: 246 – 253.

Westers, H. and K.M. Pratt, 1977 Rational design of hatcheries for intensive salmonid culture, based on metabolic characteristics. Prog. Fish Cult. 39 (4): 157 – 165.

Willoughby, H., H.N. Larson, and J.T. Bowen, 1972 The pollutional effects of fish hatcheries. Am. Fishes U.S. Trout News 17 (3): 6 – 20.

7. TABLES AND FIGURES

TABLE I. Numbers of rainbow trout of various lengths which can be produced on 4000 lpm on a once-through basis, at a temperature of approximately 10°C and a dissolved oxygen content of at least 90 percent saturation.

Length
in cm
Loading
in kg/lpm
Maximum
weight in kg
Number
of fish
2.5.5200010 000 000
5.0.7530002 160 000
7.51.04000856 000
10.01.24800432 000
15.01.45000145 000
20.01.6640070 400

TABLE II. A comparison of water consumption between intensive and extensive production of tiger muskellunge fingerlings.

Length
cm
Prod.
#/HA
Total Weight
in kg
IntensiveRearing
Days
Total Volume
Req. in m3
Loading
kg/lpm
Min.Flow
in lpm
Int.Ext.*
7.510 00017.6.5035.2301 52010 432
10.010 00042.6.7556.0452 72910 648
15.06 00091.01.091.0756 66011 080
20.06 000200.01.2166.010012 63611 440

* Average water depth one meter. Volume per hectare 10 000 m3. Provide 10.0 l pm to counter evaporation.

TABLE III. A comparison of water consumption between intensive and extensive production of walleye fingerlings

Length
cm
Prod.
#/HA
Total
Weight
in kg
Loading
kg/lpm
Flow
Req.
in lpm
Rearing
Days
Total Volume
Req. in m3
Int.Ext.*
3.232 00016.0.25641092110 144
2.712 8009.6.3527151 11510 216
4.39 60011.0.4027251 05410 360
5.46 40014.4.4532402 19510 756
7.03 20014.4.5029643 19710 922

* Average water depth one meter. Volume per hectare 10 000 m3. Provide 10.0 l pm to counter evaporation. Values for intensive rearing are theoretical.

TABLE IV. A comparison of water requirement between extensive and intensive rearing methods throughout a 175-day rearing cycle of piscivorous fish. Extensive rearing in a one ha pond (10 000 m3).

LengthRearing cycleNumber of fish during rearing cycle (in thousand)Weight per 1000
k=.00830
Total kg of fish at last day of each rearing phaseLoading in kg/lpmTotal volume of water required in 1000 m3 during rearing cycle
cmDaysExt.Int.kgExt.Int.Int.Ext.(a)
Int.A.
(b)
Int.B.
(c)
Int.C.
123456789101112
2.5Start70.015.0.149.82.1.2510.0---
4.01530.05.0.5416.22.7.2510.21.4.23.08
6.03510.04.01.818.07.2.5010.52.4.64.21
8.0557.03.74.330.016.0.5010.84.11.56.52
10.0755.03.58.342.029.0.7511.15.72.7.90
12.0954.63.414.466.049.0.7511.48.24.61.5
14.01154.23.323.097.076.01.011.711.06.82.3
16.01353.83.234.0129.0109.01.011.914.79.93.3
18.01553.43.149.0167.0152.01.312.218.413.34.4
20.01753.03.067.0201.0201.01.312.522.917.85.9

(a) Numbers equal extensive rearing

(b) One-pass system

(c) Three-pass system

TABLE V. Average Production of Walleye Fingerlings in Extensive Rearing Ponds in Michigan 1973–1978 (McClay, 1979).

YearNo. of PondsTotal
HA
Stocking Rate
#/HA
Production of Fingerlings
#/HASize in cm% Survival
19732645.948 2343 0408.76.3
19743486.875 3894 2515.45.6
19751845.9119 4994 7064.93.9
19762754.070 7034 0226.45.7
19773378.067 5516 7197.19.9
197840103.867 9877 3916.310.9

TABLE VI. Availability of oxygen based on its solubility in fresh water at 90% saturation at different temperatures and a barometric pressure of 76.00 cm mercury.

Available oxygen at 3 different effluent levels.
Temp.
(°C)
0in
(mg/1)
Coldwater fish (0out = 5.0 mg/1)Coolwater fish (0out =4.0 mg/1)Warmwater fish(0out =3.0 mg/1)
(Oin -Oout)mg/hr/lpm(Oin -Oout)mg/hr/lpm(Oin -Oout)mg/hr/lpm
511.56.5390    
611.26.2372    
810.75.7342    
1010.25.2312    
129.74.7282    
149.44.42645.4324  
169.04.02405.0300  
188.63.62164.6276  
208.33.31984.32585.38
227.9  3.92344.9294
247.7  3.72224.7282
267.4    4.4264
287.1    4.1246
306.8    3.8216
326.7    3.7222

b),c),d) Oin -Oout = Dissolved oxygen level of incoming water (0in) less dissolved oxygen level of effluent water (Oout). 0out is 5.0, 4.0 and 3.0 mg/1 for cold-, cool- and warmwater fish respectively.

TABLE VII. Loadings (kg/lpm) for cold-, cool-, and warmwater fish fingerlings according to available data on metabolic rates (mg/kg/hr).

Author and SpeciesTemp.
°C
Size
cm
Active1)
M.R.
Available O2according to Table VIMaximum loading
(kg/lpm)
   2)  
Elliot (19699 6.03803270.86
Chinook Salmon913.02503271.31
126.05202820.54
 1213.03502820.81
Pecor (1979)206.05002580.52
Tiger Muskellunge2010.03602580.72
2015.02902580.89
Huisman (1974)235.0+9002880.32
Carp2320.03002880.96

1) Active metabolic rates means rates during hatchery feeding day.

2) Elliott reports oxygen consumption rates under conditions of normal activity. These rates were doubled for Table VII, to obtain values for active metabolic rates.

TABLE VIII. A summary of the intensive rearing of 109 000 18.5 cm tiger muskellunge fingerlings in 1977 in Michigan.

Rearing Period in daysRearing PhaseSize in cm at end of phasePercent loss during phaseRearing ConditionsConversion.Production Level
ContainerWater Sourcekg/lpmkg/m3
9Sac Fry-12.0TroughWell---
18Training5.027.0.3 m3Well1.17.6026.7
26Fingerling10.823.0Tank 5.5 m3Spring3.45.4724.5
42Final18.58.6Raceway 50 m3River2.97.5330.0

TABLE IX. Formulation of the W-7 coolwater diet. In % by weight including the vitamin premix (Orme, 1978).

Ingredient Vitamin Premix (units per kg premix)
Herring meal50 D-calcium pantothenate (g)1.98
Soybean oil meal10 Riboflavin (g)1.32
Pyridoxine (g)0.88
Brewers Yeast5 Niacin (g)8.80
Dried whey5 Folic acid (mg)220.00
Blood flour5 Thiamin (g)1.10
Condensed fish solubles10 Biotin (mg)11.00
Corn gluten meal9 B-12 (mg)0.55
Menadione sodium bisulfite (mg)275.00
Vitamin premix4–6 Vitamin E (IU)8 800.00
Vitamin D3 (IU)11 000.00
Vitamin A (IU)165 000.00
Choline chloride (g)22.00
Ascorbic acid (g)16.50
Inositol (g)9.90

TABLE X. A comparison of various physiological parameters between intensively and extensively (natural diet) reared tiger muskellunge fingerlings.

Rearing Method% Green LiversHematocritHemoglobinLeucocritGlucoseChloride
Intensive9037.74.99  0.5546.0101.2
Extensive035.26.95*0.2774.498.3

* one fish only

Figure 1

Figure 1. Schematic relation between the level of intensification and the fish production per ha.

Figure 2

Figure 2. Water demands in lpm for 1 million rainbow trout at different lengths in a once-pass flow-through rearing system at a temperature of approximately 10° C.

Figure 6

Figure 6. Loading-density relationship for 4 water exchanges per hour (R=4), based on Westers' (1970) equation: kg/lpm= R/.06 × kg/m3. Areas A, B, C, D and E indicate density range for different size fingerlings under rearing conditions of optimum temperature ranges.

Figure 3

Figure 3. A comparison of water requirements in m3 between extensive and intensive rearing throughout a fingerling production cycle of 175 days' duration.

Figure 4

Figure 4. The relationship of metabolic rates in mg/kg/hr with optimum feeding levels in % B.W. for different oxygen consumption levels in g per kg food (200 for salmonids and carp; 110 for esocids).

Figure 5

Figure 5. The relationship of oxygen consumption per kg food and the feeding level in % B.W. is shown for 5 different metabolic rates in mg/kg/hr for esocids, salmonids, and carp.


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