TECHNOLOGY FOR ARTIFICIAL SPAWNING OFTECHNOLOGY FOR ARTIFICIAL SPAWNING OFSILURUS GLANISSILURUS GLANIS SPECIES – WELLS SPECIES – WELLS

• TECHNOLOGY DISPLAYTECHNOLOGY DISPLAY

• ObjectObject

• The elaborated technology is after controlled The elaborated technology is after controlled spawning of spawning of Silurus glanisSilurus glanis – wells, towards redressing – wells, towards redressing its natural populations and inserting it on aquaculture.its natural populations and inserting it on aquaculture.

• Area of implementationArea of implementation

• Implicit costumers of spawning technology are Implicit costumers of spawning technology are economical agents that have the main activity fishing economical agents that have the main activity fishing

and aquaculture.and aquaculture.

• Technological system for artificial spawning of Technological system for artificial spawning of Silurus glanisSilurus glanis – wells – wells

• For artificial spawning of wells having regard to special For artificial spawning of wells having regard to special reproductive features of species, must ensure a technical-reproductive features of species, must ensure a technical-material base specific and in accordance with different material base specific and in accordance with different stages of this process.stages of this process.

• Technological system will be apportion depending on Technological system will be apportion depending on production capacity agreed by costumer, and will ensure by production capacity agreed by costumer, and will ensure by its capacity the spawning of minimum 10 families, in order its capacity the spawning of minimum 10 families, in order to insure maintenance and conservation of genetic to insure maintenance and conservation of genetic biodiversity of species.biodiversity of species.

• Correlate with the capacity for incubation, technological Correlate with the capacity for incubation, technological system will be framed by an ensemble of earthen ponds: system will be framed by an ensemble of earthen ponds: ponds for standing-wintering, ponds for pre-maturation, ponds for standing-wintering, ponds for pre-maturation, modules for standing and maturation of breeders, modules modules for standing and maturation of breeders, modules for incubation of embrionated eggs and modules for for incubation of embrionated eggs and modules for standing and growing larvae. standing and growing larvae.

• Ponds for pre-maturation, Ponds for pre-maturation, modules for maturation of modules for maturation of breeders and modules for breeders and modules for incubation of eggs have incubation of eggs have the same properties as the the same properties as the case of pikeperch.case of pikeperch.

• For standing and rearing For standing and rearing larvae should be used PVC larvae should be used PVC or fiberglass tanks with or fiberglass tanks with volume of about 1300 l, volume of about 1300 l, fitted with proper fuel fitted with proper fuel system, adjustment and system, adjustment and discharge of water. discharge of water.

DESCRIPTION OF TECHNOLOGYDESCRIPTION OF TECHNOLOGY

• Technology for artificial spawning and rearing larvae of Technology for artificial spawning and rearing larvae of Silurus glanisSilurus glanis involves travel along following stages: involves travel along following stages:

• Assurance of breeders stock;Assurance of breeders stock;• Evaluation of phenotypic characters and sex determination;Evaluation of phenotypic characters and sex determination;• Standing, pre-maturation of breeders;Standing, pre-maturation of breeders;• Maturation of breeders;Maturation of breeders;• Induction of sexual cells maturation;Induction of sexual cells maturation;• Gathering sexual products;Gathering sexual products;• Fecundation;Fecundation;• Incubation of sexual products in special installed Incubation of sexual products in special installed

enclosures;enclosures;• Sampling and standing larvae in enclosure standings;Sampling and standing larvae in enclosure standings;• Sacking and transportation of larvae;Sacking and transportation of larvae;• Rearing larvae up to 45 days. Rearing larvae up to 45 days.

• Assurance of Assurance of breeders stock.breeders stock.

• Wells breeders used in Wells breeders used in artificial spawning artificial spawning come from stocks come from stocks reared in farms reared in farms especially for this especially for this goal.goal.

• For the establishment For the establishment of breeders stock are of breeders stock are chosen fish with age chosen fish with age of 4 – 8 years and of 4 – 8 years and weight of 6 – 10 kg. weight of 6 – 10 kg.

Morphological criteria used todetermine sex on wells

Criteria/sex Male Female

Form of genital papilla

Concave, small Bulging, ovoid

Head form Slightly foursquare shape Foursquare

Roughness of pectoral fins

Earthy Light color

The color of tegument in the ventral area

Dark Smooth touch

Sedimentation of erythrocytes

Slow Fast

• Hormonal treatment goes through after 24 hours Hormonal treatment goes through after 24 hours from stocking of breeders in the station for from stocking of breeders in the station for incubation. For induction of sexual cells incubation. For induction of sexual cells maturation on wells, it is used carp pituitary.maturation on wells, it is used carp pituitary.

• Hormonal induction of females is made in two Hormonal induction of females is made in two steps:steps:

• Step I – 0.5 mg/kg of body weight for both Step I – 0.5 mg/kg of body weight for both females and males;females and males;

• Step II – 4 mg/kg of female body weight and 3 Step II – 4 mg/kg of female body weight and 3 mg/kg of male body weight.mg/kg of male body weight.

• Before injection and gathering gametes breeders Before injection and gathering gametes breeders are anesthetized in a solution of 2-fenoxietanol (1 are anesthetized in a solution of 2-fenoxietanol (1 : 1000). : 1000).

• Gathering eggs and artificial fertilization. Gathering eggs and artificial fertilization. Method of Method of harvesting is abdominal palpation, technology known as harvesting is abdominal palpation, technology known as “milking”.“milking”.

• Abdomen is gently massaged on longitudinal direction up and Abdomen is gently massaged on longitudinal direction up and down, along axial line of abdomen, pushing eggs by the genital down, along axial line of abdomen, pushing eggs by the genital hole.hole.

• From each female collect a single portion of eggs, about 160 – From each female collect a single portion of eggs, about 160 – 200.000 eggs.200.000 eggs.

• Sperm is gathered in a crystallizer by abdominal palpation or by Sperm is gathered in a crystallizer by abdominal palpation or by using a syringe with tygon tube of 5-6 cm long. Sperm is stored using a syringe with tygon tube of 5-6 cm long. Sperm is stored for 4 hours at 4 0C. Volumetrically, average quantity of sperm for 4 hours at 4 0C. Volumetrically, average quantity of sperm gather is 2.0 – 2.5 ml/kg of body weight. Males generate between gather is 2.0 – 2.5 ml/kg of body weight. Males generate between 0.13 – 0.14 × 109 spermatozoids/kg body weights.0.13 – 0.14 × 109 spermatozoids/kg body weights.

• Artificial fertilizationArtificial fertilization• Fertilization is accomplished with mixture of sperm originating Fertilization is accomplished with mixture of sperm originating

from at list 2 – 3 males. For fertilization of 100 g of eggs are from at list 2 – 3 males. For fertilization of 100 g of eggs are required 2 ml of sperm.required 2 ml of sperm.

• Eggs and sperm are mixed in a fertilizing solution made by 0.3 % Eggs and sperm are mixed in a fertilizing solution made by 0.3 % NaCl. The volume of activating solution is 50 ml/100 g of eggs. NaCl. The volume of activating solution is 50 ml/100 g of eggs. Mixture is homogenized for 10 seconds, and then, after 2 Mixture is homogenized for 10 seconds, and then, after 2 minutes add another 25 ml of activating solution and eggs are minutes add another 25 ml of activating solution and eggs are spread on nytal frames with help of a feather. After another 5 spread on nytal frames with help of a feather. After another 5 minutes, fertilized eggs are bringing in Nucet hatcheries for minutes, fertilized eggs are bringing in Nucet hatcheries for incubation. incubation.

• Sampling and standing larvaeSampling and standing larvae• Sampling of hatched larvae is made continuously Sampling of hatched larvae is made continuously

on cushion of water, in individual tanks for on cushion of water, in individual tanks for gathering. Gathering tank is fitted with a nytal gathering. Gathering tank is fitted with a nytal cage having mesh size of 0.3 – 0.5 mm to cage having mesh size of 0.3 – 0.5 mm to constrict the larvae.constrict the larvae.

• The constricted larvae are sample with the help The constricted larvae are sample with the help of paddles and placed in special enclosure for of paddles and placed in special enclosure for standing. The operation is carried out standing. The operation is carried out continuously until the end of hatching. Counting continuously until the end of hatching. Counting larvae is accomplished directly at the time larvae is accomplished directly at the time collection.collection.

• Stocking density will be of 40 – 60 ex/l. flow of Stocking density will be of 40 – 60 ex/l. flow of water in standing tanks will be adjusted to 5 water in standing tanks will be adjusted to 5 l/min. Larvae will stay on these enclosures a l/min. Larvae will stay on these enclosures a period of 5 – 7 days up to resorption of yolk. period of 5 – 7 days up to resorption of yolk.

• Growth of larvae up on achieving adult-like Growth of larvae up on achieving adult-like phenotypic charactersphenotypic characters

• Stocking rateStocking rate• Larvae achieved from each female are stoked Larvae achieved from each female are stoked

independently on rearing enclosures.independently on rearing enclosures.• Stocking rate is 1500 ex/m3 and is determined Stocking rate is 1500 ex/m3 and is determined

taking into account technological losses for taking into account technological losses for rearing phase which in general are estimated on rearing phase which in general are estimated on 30 %.30 %.

• The height of water column in rearing enclosures The height of water column in rearing enclosures is adjusted to 20 cm.is adjusted to 20 cm.

• Technological water from enclosures will be Technological water from enclosures will be assessing physic-chemically by determination of assessing physic-chemically by determination of temperature, pH and oxygen.temperature, pH and oxygen.

• The flow of water supply in enclosures for pre-The flow of water supply in enclosures for pre-maturation is set at 5 – 7 l/min. maturation is set at 5 – 7 l/min.

• FeedingFeeding• Rearing of larvae up to outlining phenotypic characters conformable Rearing of larvae up to outlining phenotypic characters conformable

with adults is achieved on account of a feeding schedule involving with adults is achieved on account of a feeding schedule involving deliver of live food and blended yolk of egg in first 5 – 7 days of growth deliver of live food and blended yolk of egg in first 5 – 7 days of growth and then a composite diet composed of natural food and forage.and then a composite diet composed of natural food and forage.

• Feeding with natural food is achieved with very small zooplankton. The Feeding with natural food is achieved with very small zooplankton. The diet is supply with blended yolk of egg.diet is supply with blended yolk of egg.

• Feeding of larvae using natural live food in a composite diet with Feeding of larvae using natural live food in a composite diet with forage will imply the use of following feeding schedule that will allow forage will imply the use of following feeding schedule that will allow gradually passing to a feeding based exclusively on forage:gradually passing to a feeding based exclusively on forage:

• first 5 days: 85 % zooplankton, 15 % forage;first 5 days: 85 % zooplankton, 15 % forage;• next 5 days: 60 % zooplankton, 40 % forage;next 5 days: 60 % zooplankton, 40 % forage;• next 5 days: 50 % zooplankton, 50 % forage;next 5 days: 50 % zooplankton, 50 % forage;• next 5 days: 10 % zooplankton, 90 % forage.next 5 days: 10 % zooplankton, 90 % forage.• After that feeding will be assure only by forage.After that feeding will be assure only by forage.• With the passage exclusively on forage, daily ration will be determined With the passage exclusively on forage, daily ration will be determined

depending on consumption, percentage ranging from 4 to 20 % of depending on consumption, percentage ranging from 4 to 20 % of batch weight.batch weight.

• During rearing time preventive treatments are made for mix bacteria During rearing time preventive treatments are made for mix bacteria and ichtyophtiriosis; these disease are symptoms: abatement, and ichtyophtiriosis; these disease are symptoms: abatement, bleaching tail with necrosis and then fall of necrosis part of the tail. For bleaching tail with necrosis and then fall of necrosis part of the tail. For treatment use oxytetracycline + neomycin.treatment use oxytetracycline + neomycin.

• For ichtyophtiriosis use malachite green combined with formalin. For ichtyophtiriosis use malachite green combined with formalin.