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HERBIVORUS FISH BREEDING AND REARING

V. K. Vinogradov

All-Union Research Institute of Pond Fishery
P/B Rybnoye, Dmitrov, Moscov 141821, USSR

ABSTRACT

The use of the herbivorous carp species: grass carp, C. idella, silver capr, H. molitrix, bighead, A. nobilis and some of their hybrids offer good prospects for a rational utilization of the inland waters of the USSR. The feeding habits, listed briefly, are to be considered in relation to the aim of stocking these species in either reservoirs or fish ponds.

Artificial reproduction and pond rearing of the fry are practised. Fry rearing in ponds is usually in conjunction with common carp rearing. The use of herbivorous carp in polyculture with carp increased the annual production with 4 – 12 centers/ha as compared to carp monoculture. Annual production of some reservoirs has been 3 – 10 centners/ha.

RESUME

Les carpes chinoiśes: carpe herbivore, C. idella, carpe argentée, H. molitrix, carpe marbrée A. nobilis et quelques hybrides, par leurs caractères d'alimentation et de croissance spécifiques, facilitent l'utilization rationelle des eaux continentalles dans l'USSR. L'empoissonnement des lacs de barrage ou des étangs de pisciculture est adapté en fonction des besoins.

A partir d'une reproduction artificielle, les alevins sont élevés en frayères généralement mélangés aux alevins de carpes communes. Par l'utilization des carpes chinoises en polyculture avec des carpes communes la production annuelle en pisciculture a augmentée de 4 – 12 centners/ha. Dans quelques lacs de barrage l'empoissonnement des carpes chinoises à donnée une production annuelle de 3 – 10 centners/ha.

1. INTRODUCTION

Far-Eastern herbivorous fishes play an important role in solving the problem of rational utilization of inland water resources in the Soviet Union.

Interest in herbivorous fishes is quite natural. With the utilization of herbivorous fishes, which are consumers of the first order, it is possible to utilize directly a considerable part of primary production formed in the water and to create a very favourable ecosystem in bio-energetic and economic respects in which the marketable production is obtained in the second link of the trophic chain. Other ichthyofauna representatives provide production in the third (zooplankton feeders) or fourth (fish predators) link of the trophic chain, and it is well known that production of every next link in relation to the previous one constitutes about a 90% loss of energy. That is why with all existing diversity in local ichthyofauna and great possibilities for assimilation of new foreign species, herbivorous fishes for the nearest future are the basic and the most effective reserve of fish production increase in inner waters of southern and moderate zones of the country. Besides, herbivorous fishes are not only a source of food. Especially attractive is the possibility of their utilization for biological improvement of reservoirs: control of excessive plant growth and improvement of the sanitary condition.

2. SPECIES CHARACTERISTICS

2.1 Grass carp

Herbivorous fishes of the Far-Eastern complex comprise three species of the carp family (Cypronidae) differing considerably by their feeding nature: grass carp, Ctenopharyngodon idella (Val.), silver carp, Hypopthalmichthys molitrix (Val.) and bighead, Aristichthys nobilis (Rich.).

Grass carp feeds on macrophytes. The specific food supply for grass carp in intensively run ponds is not large; the fish destroys it quickly and then changes to substitutes, including food mixtures which it utilizes less efficiently than carp. In pond polyculture grass carp plays an effective role as biological meliorator.

In fish ponds it is advisable to use grass carp for control of plant growth and to schedule the stocking to provide normal water flora. When grass carp are stocked into natural waters, the biological balance (grass carp - water plants - freshwater fishes) should be taken into consideration. For stocking purposes reservoirs should be chosen with well formed and productive biocenosis.

The high meliorative ability of grass carp may be utilized in controlling biological obstacles in the management of technical and agricultural reservoirs (irrigation systems, cooling reservoirs of thermal power stations, rice fields under water fallow, etc.). Due to economic specificity of such reservoirs, a fast and comparatively complete removal of weeds is necessary. That is why in such cases high stocking rates of grass carp may be applied to utilize fully specific peculiarities of this particular voracious phytophagan (Vinogradov and Zolotova, 1974).

2.2. Bighead

Bighead is a partially herbivorous fish. This species prefers zooplankton, but phytoplankton and detritus also play an important role in its feeding. Bighead has a higher growth potential than silver carp (not only in the South, but in the Middle zone as well); however, to realize this potential a considerable amount of zooplankton is required (not less than 3–5 mg/l). Too dense stocking of ponds with bigheads (over 500 – 700 yearlings/ha in the South) may result in reduced carp growth due to competition for zooplankton.

Bighead is a quiet school fish easily caught from lakes and reservoirs. In every particular case the problem of bighead stocking must be solved with food reserve peculiarities and reservoir ichthyofauna composition considered.

2.3. Silver carp

The silver carp feeds on phytoplankton, detritus also playing a significant role. Planktonic bacteria are also utilized (Kutznetsov, 1977). A considerable potential is found in all climatic zones (not only in ponds, but in many lakes and reservoirs). No direct competition for food is observed with carp or other species in polyculture. Mutual positive influence is exercised under combined rearing with carp. A considerable increase in herbivorous fish production may be obtained due to silver carp.

2.4. Hybrids

Reciprocal hybrids of grass carp and bighead are also of interest. They possess a good growth and survival rate. By feeding habits they occupy an intermediate position between the parent species, due to which they obtain a high flexibility in reservoir food assimilation. In reservoirs, poor in zooplankton, hybrids transfer to detritus and phytoplankton and leave bighead behind in growth rate. Like parenteral forms, hybrids are school fish. Both hybrids inherited a quiet behaviour from bighead which facilitates their catch from lakes and reservoirs. Under moderate climate they grow better than silver carp.

Bighead hybrids are fertile, that is why it is advisable to plant them into reservoirs where no conditions for natural reproduction exist. Morphologically second generation hybrids do not differ from first generation hybrids (Voropaev, 1975).

2.5 Feed selectivity

There is a definite selectivity in silver carp and bighead vis-à-vis the various algae groups. Diatomaceous, protococcan and green algae are the most preferable ones. At the same time blue-green algae (Aphanizomenon, Oscillatoria, Anabaena, Microcystis, etc.) may serve as a basic food for silver carp and bighead, as well as detritus from blue-green algae, their utilization not affecting fish condition.

Selectivity of silver carp and bighead to various phytoplankton species and the presence of preferable forms is to a great extent accounted for by the mechanical selectivity determined by the peculiarities of the filtrating gill structures of these fishes. Silver carp filters small phytoplankton forms and bighead filters zooplankton and larger algae. No considerable differences in filtration structure are observed in silver carp of various ages and sizes, the distance between gill rakers almost does not change and fluctuates between 20 and 25 μ. That is why food composition of silver carp of various ages (from fry to breeder) is similar. Silver carp prefers phytoplankton of 20 – 45 μ in size.

As bighead grows, the distance between gill rakers increases considerably, namely from 20 to 75 μ. As a result, many small phytoplankton forms become inaccessible for the fish. Bigheads reaching. 500 g feed mainly on algae of 45 – 70 μ, and those weighing over 1000 g utilize algae form 75 to 100 μ (Vinogradov, 1976; Voropaev, 1975; Danchenko, 1974). The circumstance mentioned must be considered in evaluating food reserve in reservoirs when rearing bigheads of various ages.

The ability of bighead and especially silver carp to filter phytoplankton and detritus served as a basis in suggestions to use these fishes for biological purification of water. It is supposed that silver carp and bighead introduced into reservoirs will make for the improvement of sanitary conditions in reservoirs by utilizing considerable amounts of phytoplankton and detritus (Vovk, 1974). No practical experience of silver carp and bighead application for biological purification of water exists.

3. REPRODUCTION

Effective natural reproduction if herbivorous fishes in most reservoirs, lakes and other waters is hardly possible. The basic source to obtain herbivorous fish stocking material is artificial reproduction. With the present state of knowledge and artificial reproduction biotechniques it is possible to organize stocking material production of these species in volumes fully satisfying fishery demands. About 1.5 billion fry of herbivorous fishes are produced annually in the USSR. In the future fry production will increase up to 5 billion at least (Vinogradov, 1976). In this connection the development of scientifically sounds methods of herbivorous brood fish management was a most important problem.

At present the most favourable areas for breeder rearing have been determined and basic methods of grass carp and bighead brood stock formation and exploitation have been developed (Vinogradov, 1977) In breeder rearing and brood stock formation it is necessary to control their genetic differences to prevent inbreeding. Two-line breeding is recommended. It is advisable to use fish groups of Amur and Chinese origin as initial lines whose crossing produces heterosis effect (Polyarush, 1978). These are only first steps to organizing selection and breeding of herbivorous fishes.

Unlike carp, grass carp and bighead are still “wild” objects, newly introduced from nature. That is why the necessity and importance of selection and breeding for their fastest domestication and breeding quality improvement is quite evident.

Artificial reproduction of herbivorous fishes is based on the physiological method of offspring obtaining. The technological scheme of artificial reproduction includes the following basic steps.

Mature sexual products are obtained with the injection of hormones. Fractional (two time) injection of hypophysis suspension of carp, bream, crucian carp, European catfish is practised. In bighead rearing chorionic gonadotropin is used. The dosage of the hormones in the first and second injection is in a proportion of 1 : 10.

The interval between the injections is 12 to 24 hours. After the injection the breeders are maintained in small earthen ponds (20 – 30 m2) or bath containers. The rate of female ripening after the injection depends on water temperature. At 20 – 22 °C females ripen in 10 – 12 hours; with temperature increase to 26 or 28 °C ripening time is reduced to 7 – 10 hours. Periodic inspection helps to determine the moment of female ripening. The ovulated eggs should not stay in the female body cavity since they deteriorate as a result of asphyxia.

The eggs are fertilized using the “dry” Russian method. Egg incubation is carried out in VNIIPRKh incubation apparatuses (capacity 2001: about 1.5 mln eggs) and the fry are kept in IVL-2 apparatuses (capacity 2001: up to 2 mln fry). Survival from eggs to larvae is 50%.

VNIIPRKh and IVL-2 apparatuses may also be used for egg incubation and fry rearing of carp and buffalo. So, the shop equipped with these apparatuses is universal enough (Vinogradov and Savin, 1978). It is advisable to operate shops with capacity not less than 100 and not more than 300 mln herbivorous fish fry.

For efficient herbivorous fish reproduction it is absolutely important to regulate temperature conditions during the various stages of the technological process. Operation under optimum conditions (22 – 25 °C) makes for the improvement of fishcultural results, strict rhythm in the production cycle and reduces to a great extent the spawning period.

In areas with unfavourable climatic conditions it is advisable to establish reproduction facilities using the discharged heated effluents of thermal power stations; due to this, favourable conditions for breeder rearing are created and optimum temperature conditions maintained in the period when offspring is obtained. This fact is confirmed by the operation of such complexes in the Soviet Union (Bagrov, 1972; Sobolev, 1976), Poland (Wolney, 1971; Jähnichen and Wolf, 1978), German Democratic Republic (Auerbach, 1978).

4. FRY REARING

Fry at the stage of exogenous feeding are the final phase of reproduction complexes. Such fry are transported to various farms. Transportation is practised in polyethylene bags filled with water and oxygen. During transportations not exceeding 24 hours 50 000 fry are placed in 40 1 bag (⅓ water, ⅔ oxygen). Hundreds of millions of fry are transported by planes and trucks annually.

When stocking rearing ponds with fry at the stage of exogenous feeding often considerable losses are observed. When the fry are reared to a more viable stage (till the transfer to feeding with large forms of zooplankton at an individual body weight of 25 – 30 mg), the mortality rate is considerably reduced during the further stages of rearing.

Fry rearing in ponds is widely practised. Biotechnical methods applied aim to have a high rate of food reserve production (by means of organic and mineral fertilizer introduction into ponds) with successive replacement of small zooplankton forms with larger ones, while favourable oxygen conditions are preserved. The water temperature must be over 20 °C. The oxygen content must be 6 – 12 mg/1 (Panov et al., 1972). Methods are being developed of fry rearing in troughs and tanks with the application of artificial food (Solonin and Panov, 1977).

Herbivorous fish fingerlings are reared together with those of carp. It is advisable to place fry in ponds soon after they are filled with water (not later than after 7 days). Under favourable rearing conditions the survival of fry stocked at first exogenous feeding is 40% in the South and 30% in the Middle zone. When rearing ponds are stocked with larger fry, the survival averages 70% in the South and 50% in the Middle zone. In the South the carp rearing ponds are additionally stocked with silver carp (50 000 fish/ha), bighead (30 000 fish/ha), grass carp (without additional feeding with vegetation applied; 10 000 fish/ha). In areas with moderate climate lower stocking rates of larvae are used. Average fingerling weight is 25 – 30 g in the South and 15 – 20 g in the Middle zone.

During the autumn harvest of the rearing ponds the peculiarities of the behaviour of the various species must be taken into consideration: when the pond is lowered silver carp is the first to descend, bighead is the second and grass carp and carp are the last. These pecularities allow the fish to be naturally sorted by species during pond lowering.

Herbivorous fish fingerlings are notable for their active behaviour in wintering ponds. They continue to swim even when the water temperature is only 0.5°C. This causes mass losses of carp. It is therefore advisable to carry out wintering with either herbivorous fish or carp in the pond alone.

5. PRODUCTION

Herbivorous fishes have a high value for pond fish polyculture. At present the first stage of polyculture assimilation is being completed. Additional production is obtained by the utilization by phytophagans without radical changes in biotechniques applied in carp monoculture. Already, it proved possible to double pond productivity and to obtain additional 10 to 15 centners/ha of market production in the South and 3 to 5 centners/ha in the Middel zone without considerable increase in food and fertilization expenditure. Herbivorous fish provide over 20% of pond farm market production in the whole country and 50 to 70% in the South. The next stage is transfer to more perfect polyculture forms providing considerable increase in production due to herbivorous fishes, namely, from 30 to 50 centners/ha. The new polyculture from requires a detailed study of feeding peculiarities and food relations of various fishes and determining optimum value of each one at various intensification levels, as well as development of methods to stimulate the food reserve formation. In the future polyculture will become more complicated due to introduction of new fish species e.g. buffalo, Ictiobus cyprinella, Ictiobus niger, Ictiobus bubalus; paddlefish, Polyodon spathula; channel catfish, Ictalurus punctatus.

The problem of a wider utilization of herbivorous fishes for lake and reservoir stocking is being solved. Reservoir area planned for immediate stocking with herbivorous fishes exceeds 2 mln ha. The exploitation of a number of reservoirs in Northern Caucasus and Moldavia, where 3 to 10 centners/ha of herbivorous fish are produced without any additional intensification measures, is indicative of their high potential for planting reservoirs of a comple destination. Calculations show that reservoirs in the European part of the USSR may provide not less than 1 mln centners of marketable herbivorous fish (Vinogradov, 1976).

The requirements in respect of the basic parameters and the hydrochemical conditions are the same for herbivorous fish rearing as they are for carp. Temperature is the principal abiotic factor limiting the application of herbivorous fishes. These fishes are more heat-loving than carp; in the South their growth is as good as that of carp but in reservoirs situated in the Middle zone they grow slower than carp (especially silver carp). At the same time they winter well under severe conditions of Central and North-Western areas of this country. That is why farms for herbivorous fish fattening may be established in all areas where carp is being reared.

It is evident, that with advancement from the South to the North and vegetation period reduction, the efficiency of reservoir utilization for herbivorous fish fattening is lowered.

6. REFERENCES

Bagrov, A.M., V.A. Kostylev, and I.G. Barsov, 1977 Experience of the Kurskaya TETs effluent utilization for herbivorous fish breeding. In: Results and prospects of fishcultural utilization of herbivorous fishes. Kiev, Naukova dumka, 23 – 24.

Vinogradov, V.K., 1976 On herbivorous fish utilization for natural reservoir stocking. Trudy VNIIPRKh, 25: 14 – 21.

Vinogradov, V.K. and L.V. Yerokhina, 1977 Manual on biotechniques of herbivorous fish breeder rearing and brood stock exploitation. M.MRKh SSSR, VNIIPRKh, 68 pp.

Vinogradov, V.K. and Z.K. Zolotova, 1974 Grass carp influence on reservoir ecosystem. Hydrobiol. zh., 10 (2): 90 – 98.

Vinogradov, V.K. and G.I. Savin, 1978 Shop for egg incubation and larvae maintenance. Rybovodstvo i rybolovstvo, 1: 7 – 9.

Vovk, P.S., 1974 On silver carp (Hypophthalmichthys molitrix (Val.) utilization for fish productivity raising and eutrophication level lowering of the Dnieper reservoirs. Voprosy ikhtiologii, 14 (3): 406 – 416.

Voropaev, N.V., Morphological traits, feeding and some fishcultural indices of silver carp and bighead and their hybrids. In: New studies on ecology and breeding of herbivorous fishes. M. Nauka, 206 – 217.

Voropaev, N.V., 1975 Biological peculiarities and economic value of silver carp and bighead hybrids. Sb. nauchn. trudov. Herbivorous fish polyculture in pond farms and natural reservoirs, 15 M. VNIIPRKh, 19 – 44.

Danchenko, A.D., 1974 Functional morphology of filtration gill apparatus and feeding selectivity of silver carp and bighead. Sb. nauchn. trudov. Pond fishery intensification, II, M. VNIIPRKh, 199 – 208.

Yerokhina, L.V. and V.K. Vinogradov, 1978 Rybovodstvo i rybolovstvo, 1: 4 – 6; 3: 3 – 5.

Kuznetsov, E.A., 1977 The role of plankton bacteria in silver carp feeding. In: Results and prospects of fishcultural utilization of herbivorous fishes. Kiev, Naukova dumka, 74 – 75.

Panov, D.A., L.G. Motenkova and L.V. Khromov. 1972 Biological grounds of rearing young herbivorous fish. In: Acclimation of herbivorous fishes in reservoirs of the USSR. Kishinev, Shtiintsa, 95 – 98.

Polyarush, V., 1978 Two-line breeding of silver carp. Rybovodstvo i rybolovstvo, 4: 8.

Polyarush, V. 1972 Manual on biotechniques of herbivorous fish breeding and rearing. M. MRKh SSSR, VNIIPRKh, 72 pp.

Sobolev, You, A., 1976 Herbivorous fish offspring obtaining with GRES warm water utilization. Trudy VNIIPRKh, 25: 114 – 122.

Solonin, V.P. and D.A. Panov, 1977 Young herbivorous fish rearing in troughs with artificial feed utilization (methodic instructions). M. MRKh SSSR, VNIIPRKh, 41 pp.

Auerbach, W., 1978 Erbrütung und Aufzucht von Karpfen und pflanzenfressenden Fischen. Z. Binnenfischerei DDR, 25 (5): 159.

Jänichen, H. and K. Wolf, 1978 Studium der Biotechnologie zur künstlichen Vermehrung von pflanzenfressenden Fischen (Ctenopharyngodon idella, Hypophthalmichthys molitrix und Aristichthys nobilis) in der Warmwasseranlage Goslawice (VR Polen). Z. Binnenfischerei DDR, 25 (7): 194 – 201.

Wolny, P., 1971 Informacia o pierwszym w Polsce tarle amura bialego i tolpygi bialej N1970r. Gospodarka rybna, 23 (3): 4 – 9.


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