A. Antalfi
National Fishery Inspectorat, Budapest, Hungary
ABSTRACT
Information on the general biology and the farm pond and artificial reproduction procedures is presented.
Generally the fry are reared in 0.2–1 ha ponds managed to have a good quantity of rotifers and various nauplii. Pond management before and during the 30 day rearing period is described.
Experiments to further rear the 3–5 cm fingerlings in cages have not been very successful.
RESUME
Sont expliquées les techniques de reproduction semi-naturelle et de reproduction artificielle par stripping.
Les alevins sont élevés en étangs de 0.2 – 1 ha où se trouvent des quantités abondantes de rotifères et de différents nauplies. La gestion des étangs avant et pendant l'alevinage est décrite. Les essais d'élever les alevins de 3 – 5 g en cages n'ont pas abouti à des succès.
Pike perch, Stizostedion lucioperca L., is one of the most valuable fishes. Because of its palatibility and bonelessness, demand on the markets is increasing.
Before going into details of its propagation and rearing, some words have to be said about this fish.
Area: Originally it lived in the fresh and brackish waters of Central- en East-Europe, and the area of the Eastern-Sea. As a result of introductions it can now be found in the whole of Europe and in North-Afrika.
Environment: Lakes rich in feed, slow river parts and back branches with a depth of a few meters, which warm up early in the spring. Living on the bottom, it prefers to stay on the lee side of stones and tree trunks. In lakes it can be found beside vegetation.
Reproduction: In Europe the spawning season is March–April, when the water temperature rises to 10–14°C. Males prepare nests by cleaning - with the help of caudal fin - the roots and stones from mud in a circle of 30–40 centimeters. With his continuous ‘dance’ he attracts the female over the nest, and spawning takes place in few hours. Diameter of eggs is between 1–1.5 millimeter, they are stock to the nests, and hatch in 110 day-degrees. The male guards the nest for 3–4 days, and keeps fishes away, which eat eggs. The males reach sexual maturity after the second or third summer, the females after the third or fourth.
Feeding habits: During the first four weeks the fry feed on planktonic organisms. After having reached the length of 35–40 mm it turns to preying, when the water temperature is above 10°C. Cannibalism is frequent. The main forage fish are cyprinids.
Growth:
| Age | length | weight | ||
| 1 | year | 120–150 | mm | 10–30 g |
| 2 | " | 200–300 | " | 120–250 g |
| 3 | " | 300–400 | " | 300–1000 g |
| 4 | " | 500–600 | " | 1200–1500 g |
In Hungary big specimens reach the size of about 1 meter and weights between 15–20 kilogrammes.
Other remarks: In carp ponds it can be used to eliminate trash fishes, and is a good indicator organism for pollution, oxygen demand is one of the highest. No communicable diseases are known.
There are two basic methods for propagation of pike perch.
The latter can be done in two ways:
Egg collecting is practised in Hungary since 1910 from Lake Balaton. The method was introduced in other waters, e.g. Lake Velence, in the fifties.
Nests prepared from willow roots, or juniper branches are placed in the spawning areas in March, when the water temperature reaches 10°C. For easy control the nests are attached to a rope and fixed by poles. After one or two days it can be ascertained whether a male found the nest, because the nests are clean from mud. Once spawning has started the nests have to be collected every day to be taken to the hatching place. Treatment of these nests is similar to those exposed to spawning ponds.
The pond procedure of propagation of pike perch starts in the year preceding the planned spawning season, with aquisition of breeders. Sex ratio: 1:1. Brood fish are kept in wintering ponds from the autumn to the spring. Forage fish for breeders should be provided in a quantity of 20–25 percent of their body weight. Pike perch also feeds at very low temperatures and autumn and winter feeding is essential for development of the sexual products.
In spring breeders have to be separated by sexes. This has to be done when water temperature is between 6–8°C. In this period the belly of the females is already swollen, while the ventral part of males is getting a dark colour and the body is slim.
After having prepared the nests, males and females are placed into the ponds. Nests can be made of willow roots, juniper branches, or synthetic fibre. They have to be placed on the pond bottom, before filling the ponds with water, counting 10–15 m2 area for each. Nests have to be in 1.5–2 m deep water and their places should be marked by floats.
On the second day after breeders have been stocked, nests should be checked. Eggs can be transported for longer distances, only 24 hours after spawning.
Appropriate oxygen supply of nests full of eggs can be achieved only by the water spray method of Woynarovich. For this purpose a water spray tent has to be made.
Three to four hours before hatching the eggs have to be transferred to ponds. Eggs are examined microscopically in Petri dishes, and when hatching is about to start in a few minites, the nests can be put into the ponds.
Experiments for using this method have been carried out since 1977 in the Fry Breeding Fish Farm of the Union of Fishery Cooperatives at Dinnyés.
Keeping of breeders through the winter is similar to that of breeders used for spawning on nests. When the temperature of the storage ponds rises to 10°C, breeders are transferred to the hatchery into basins, where the temperature can be regulated. Males and females are kept together. In four times 24 hours the temperature is raised gradually to 14°C, 1°C every day.
On the fourth day sexes are sorted into separate basins of 3 × 1.5 m, water depth 80 cm. Water of basins has to be changed every 8 hours. Aeration from the bottom is necessary. Oxygen level of the water has to be about 10 mg/1 at a temperature of 14°C. When separating the sexes, females are injected with carp pituitary, 2 mg per 1 kg of body weight. Pituitary powder is dissolved in salt solution, of 65 per cent.
Weight of breeders is usually between 1500 and 3000 g. Pituitary is injected in 1 cm3 solution, into the back under the dorsal fin.
When manipulating the spawners they are anaesthetized by the help of MS 222/Sandoz/ in a solution of 1:80.000. Male spawners receive 3 mg of pituitary for 1 kilogramme of body weight.
Fourty eight hours after the pituitary treatment the depth of water in the basins is reduced from 80 cm to 15–20 cm. Spawners are anaesthetized again and eggs are taken by stripping. The eggs are stripped into bowls of 2–2.5 litres (100–200 g per bowl).
Anaesthetized males are layed on the back and milt is stripped by light pressure. Milt is siphoned by long pipettes and is dropped on the dry eggs. After this milt and eggs are carefully mixed with a feather.
Having done this, 20 ml. of fertilizing solution is added and eggs are stirred for 10 minutes. During slow stirring the bowls are completely filled with fertilizing solution and after 30 minutes the eggs are rinsed repeatedly with pure pond water.
Composition of fertilizing solution:
| 15 | litres of pure pond water |
| 4 | g of NaCl |
| 5 | g of Karbamide |
Eggs are left for one hour in the bowls and moved from time to time. Before placing them into the hatching glasses they have to be rinsed with tannic solution, 3 g tannin in 10 litres of pond water. The fluid is poured from the eggs and the bowls are filled with tannic solution. After 10 seconds of stirring the solution is removed from the eggs. Hereafter the eggs are rinsed again with pond water, and placed into 8 litre zug-glasses where they are hatched (20 000–30 000 eggs can be put in one glass).
After hatching the fry of pike perch swim up vertically to 20–30 centimeters in the glasses.
On the 4th – 5th day the fry will take air and start independent life. In this stage they can be siphoned into tanks and stocked in ponds of 0.5–1 hectares for rearing.
The fry can also be kept in sieve cloth boxes of 40–80 centimeters, or in big zug-glasses of 80–150 litres, with a moderate water supply.
For first feeding Rotatoria or nauplii are given in both of the above mentioned cases. It is very important to filter the bigger Cyclops from the collected zooplankton, because they can cause great damage among the fry of pike perch.
For rearing the fry of pike perch to the size of 30–50 mm, ponds of 0.2–1 hectare are the most suitable.
The most important activities for successful fry rearing are:
To keep the ponds dry during winter. The pond bottoms have to be tilled to a depth of 10 centimeters in the autumn or in the spring preceeding the rearing season.
Before stocking the ponds they are filled up to 30 per cent. The ponds are then fertilized with organic phosphoric acid derivative (1 ppm), dispersed equally on the water surface, to promote the development of rotifers.
After stocking, a gradual filling of pond is recommended. When the pond is filled up, it has to be inoculated with planktonic organisms collected from other ponds.
The water of the ponds has to be fertilized every second day with artificial fertilizers. During the rearing period of 28–30 days 50–70 kg nitrogen, and about 200 kg of phosphorus are needed, depending on the water quality. Investigations on plankton have to be carried out every day, when quantitative and qualitative control is necessary. When examining the species it is important to state the percentage of bigger Daphnia species present. If this is higher than 50 per cent of total zooplankton, survival of fry will be poor, and no good results can be expected. Best feed organisms for plankton eating pike perch are: Cyclops canthocamptus, and small Bosmina, Leptodora and Alona species.
Water of nursery ponds has to be treated with artificial fertilizers so that 100 liters should always contain 1 cm3 of plankton killed with the help of formaldehyde.
If this is achieved, cannibalism can be avoided to the length of 30–40 mm, when the water temperature is between 20 and 24°C.
Nursery ponds can easily be harvested without injuring the fry by water drainage and by use of nets at the outlet.
Stocking rates should be: 1 million eggs ripe for hatching or 500 000 feeding larvae for one hectare.
Survival rates to be expected after 28–30 days: 3–5 per cent in case of stocking with eggs, and 20–30 per cent when feeding larvae were stocked.
According to our experiments pike perch can be reared for 30 days, and to the size of 40 mm on a large scale, with the described semi intensive method, in ponds of 0.2–1 hectare.
After reaching the size of 40 mm pike perch turns to prey on fish. Even in cases when there is enough forage fish at hand, cannibalism will start, because of growth differences. It is advisable to stock pike perch of such age in carp ponds in a quantity of 200–300 per hectare. In this way we can expect harvesting 5–10 percent of the quantity stocked as one summer fish with a weight of 10–30 g, depending on the abundance of forage fish.
Experiments on rearing one summer pike perch in cages and in basins have been carried out at the Fry Breeding Fish Farm of Dinnyés without success.
Causes of this may be that:
Pike perch does not take artificial feeds
In intensive rearing it was not possible to collect sufficient quantities of small size plankton, consequently after 14–15 days serious losses occurred, and later on cannibalism appeared because of size differences.
To counter balance the difference in growth size grading ought to be carried out every 4–5 days. Because of the sensitive nature of pike perch this is not possible. When manipulation is frequent, it is impossible to avoid injuries of skin. Saprolegnia will appear before the caudal fin which is the most sensitive part and fish will be killed.
When rearing pike perch of more than 5 centimeters in cages (1000–5000 pieces for 1 m3) we secured optimal oxygen levels by using ejectors for aeration. In spite of optimal environment, and great quantities of forage fish, cannibalism could not be stopped.
10.000 Pike perches of 50 millimeters were stocked to a cage of 4×2 meters (depth 1.4 m). After 60 days 200 specimens of 120 millimeters were recaptured (2 per cent). Pike perch were fed with 50 000 common carp, and herbivorous carp fry of 25–30 mm. Commercial value of 200 pike perch of 120 mm (3 kg), in Hungary, is 1 600 Forints while 50 000 fry of common and herbivorous carp can be sold for 12 500 Forints.
Consequently economic production of pike perch is not possible even when only the costs of forage fish are counted, let alone when also considering other expenses, such as that of labour etc.
There are many unsolved questions in the field of intensive rearing of pike perch, and always more experiments will be needed to get the desired answers. This work has to be done by scientists and fish breeders together.
Semi intensive rearing in ponds is an elaborated and safe method, by which stocking material for fish farms and natural waters can be produced.
Some references on pike perch culture are included in the references.
Antalfi-Tölg, 1971 Halgazdasági ABC. ABC of Fish Farming.
Haki, Tógazdasági Haltenyésztés. Fishery Research Institute: Fish Breeding in ponds.
Pollet, M., 1959 Poisson Royal le Sandre. Paris.
Ribiánszky-Woynarowich, 1962 Hal, Halászat, Halgazdaság. Fish, Fisheries, Fish Farming
Zimmer, F., 1940 A “Fogas”. The Pike perch.
Baldi Bálint: “HALÁSZAT” XIV: 20; XIII (3): B2
Tölg István: Áprilisi téma a süllöivatás. Spawning of Pike perch. “HALÁSZAT” XIII (3): 56 – 57.
Biró Péter: “HALÁSZAT” XVI: 98 – 99.
H. Tamás Gizella: A scuka-süllö és harcsa-ivadék táplálkizása élete elsö néhány hetében. Feeding of Fry of Pike, Pike perch, and Wels, in the first weeks of their life. “HALÁSZAT” XVI: 80 – 81.
