TECHNOLOGY FOR ARTIFICIAL SPAWNING OF STIZOSTEDION LUCIOPERCA SPECIES – PIKEPERCH

1. TECHNOLOGY FOR ARTIFICIAL SPAWNING OFSTIZOSTEDION LUCIOPERCA SPECIES – PIKEPERCH • TECHNOLOGY DISPLAY • Object • The elaborated technology is after controlled spawning of Stizostedion lucioperca – pikeperch, towards redressing its natural populations and inserting it on aquaculture. • Area of implementation • Implicit costumers of spawning technology are economical agents that have the main activity fishing and aquaculture.

2. Technological system for artificial spawning ofStizostedion lucioperca – pikeperch • In correlation with capacity for incubation, technological system will be constituted by an assembly of earthen ponds: wintering ponds, standing-wintering ponds, standing-maturation ponds, controlled spawning ponds, modules for standing and maturation of breeders, modules for incubation of embrionated eggs and for standing larvae. • Spawning ponds. These are small surface ponds (0.25 – 0.5 ha), with continuously supply and discharge of water, hard bottom and water depth of 0.70 – 0.90 m, rarely 1 – 1.2 m. In these ponds are fixed pallets (nests) on which breeders will spawn.

3. Fixing pallets on spawning pond is carried out 2 – 3 m from bank (in order to observe the moment of spawning) and the distance between pallets on the side of pond is of 8 – 10 m (Fig. 1).

4. The installation for incubation of pikeperch eggs is aimed at achieving optimum condition for incubation of eggs. Is assured water supply, maintenance of a optimum depth, treatment of eggs and discharge water individualized from each hatchery. • Installation constituent • Installation consists of following subassemblies: • overall preparedness hatching; • installation of water supply for hatcheries; • hatchery; • support for hatcheries; • installation for water discharge.

5. Overall preparedness hatching • Consists of: • installation for technological water supply; • trays for fertilization; • support frames for eggs; • platform support. • Nucet type hatchery use for incubation of pikeperch eggs • Nucet type hatchery is made up of a metal box with dimensions 60 × 60 × 55 cm in which introduces a cage made of Nytal bolt having mesh size of 200 μm and dimensions of 52 × 52 × 46 cm. Hatchery has a volume of 180 l and a maximum incubation capacity of 1.5 kg of eggs.

6. The module for standing of breeders is used for breeders during the period before spawning. • Composition of unit for standing of breeders • The module consists of the following major sub-assemblies: • parallelepipedous tank with useful volume of 4.0 m3; • installation of discharge and adjustment of water level; • installation of water supply.

7. DESCRIPTION OF TECHNOLOGY • The technology for controlled-artificial spawning and rearing of larvae of Stizostedion lucioperca species involves travel along following phases: • Assurance of breeders stock; • Evaluation of phenotypic characters and sex determination; • Standing, pre-maturation of breeders; • Assessment of reproductive condition; • Placing breeders in spawning ponds; • Spawning; • Sampling the pallets; • Incubation of sexual products in specially prepared enclosures; • Packing and transportation of fry.

8. Assurance of breeders stock. • Pikeperch breeders needed for stations of production and rearing of fry come both in natural environments, by catching them in early spring, and stocks reared in farms especially for this goal. • Preliminary evaluation of breeders • Pikeperch breeders will be assessed immediately after catch for evaluation of phenotypic characters and determination of sex. Selected breeders have length of 30 – 50 cm and weight of 1.0 – 3.0 kg. • Breeders must display body integrity, biological qualities and a good physiological shape. • Assessment of reproductive condition • The method of assessing both the maturation stage and polarity factor involves collecting a minimum of 5 eggs from posterior part of ovary by practicing a puncture. • For determination of nucleus or germinal vesicle position, ova will be cut-off exactly along the axis of animal-vegetal pole. After this operation, nucleus position will be observed and evaluated. • For determining the polarity factor measured under the stereoscope distance from the top of germinal vesicle to animal pole and the distance from animal pole to vegetal pole. • Small values of the coefficient indicated a high degree of polarization for ova so an advanced stage IV of maturation.

9. After evaluating reproductive condition, females who are in advanced maturing stage are selected and populated in spawning pond, in which are fixed the pallets. In the pond are also populated the males that release a few drops of sperm on a slight palpation of abdomen. In a pond of a hectare are release 10 – 12 females and as many males. The batch has to be more uniform choosing breeders of close size.

10. Spawning; • Spawning takes place in the early hours of sunny mornings. • The nests with eggs are getting away from the spawning pond on the bank, carefully detached from the pallets and are carrying in barrows with water to the spawning station (Fig. 7). • Incubation pikeperch eggs. • The nests with pikeperch eggs are placed carefully in Nytal cages from Nucet hatcheries and ensure continuously water supply to a flow of 8 l/min.

11. Females under the II and III maturation stage are hormonal stimulated and spawned artificially • Hormonal stimulation • For hormonal stimulation of pikeperch will be used pituitary extract of carp. Females are stimulated with 5 – 15 mg/kg of body weight depending on maturation stage and for males are used 3 – 5 mg/kg of body weight. • Injection is carried out either in dorsal muscle either on the base of pectoral fin. After injection, breeders separated on sex are placed in tanks for maturation on hatchery station. Ovulation can be achieved after about 48 hours from injection. • Gathering eggs and artificial fertilization. Gathering eggs is done in females perfectly mature by slightly palpation of abdomen. • From a pikeperch female is gathering a quantity of eggs between 150 and 200 ml.

12. Fertilization • Eggs gather from a single female are fertilized individually with a mixture of sperm from 5 – 6 males. Quantity of sperm used is 2 ml for a portion of 200 ml of eggs. • The mixture is homogenized then adds the fertilizer liquid. Time for fecundation is about 3 – 5 minutes. After passing the three minutes, eggs are spread on support frames of Nytal.

13. Incubation of eggs • Incubation of eggs will start with introduction and attach of frames in the Nucet hatcheries. Duration of hatching is variable depending on daily mean temperature: 11 days at 13 0C, 4 – 5 days at temperature of 14 – 15 0C. • For pikeperch, optimal temperature for incubation is 15 0C. Mean duration of embryogenesis on these values of water temperature is about 5 – 6 days. • The flow of water supply on hatcheries up to gastrulating stage of eggs will be adjusted for such a way as to create a stream of water that does not produce displacement of eggs from the frames (3 – 4 l/min). After gastrulating, the hatchery is increasing the volume of water higher (5 – 7 l/min). During embryogenesis, oxygen level in enclosures of incubation will be maintained at the minimum values of 5 – 6 mg/l. • Control mould during incubation time will be achieved by bathing eggs with formalin solution for 15 minutes. The first treatment will be achieved in 24 hours from fertilization, and following at intervals of 12 hours until the appearance of ocular vesicles. • After hatch, frames out of hatchery, and larvae are kept in hatcheries until resorption of yolk.