TECHNOLOGY FOR ARTIFICIAL SPAWNING OF SILURUS GLANIS SPECIES

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TECHNOLOGY FOR ARTIFICIAL SPAWNING OFSILURUS
GLANIS SPECIES WELLS

• TECHNOLOGY DISPLAY
• Object
• The elaborated technology is after controlled
  spawning of Silurus glanis wells, 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.

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• Technological system for artificial spawning of
  Silurus glanis wells
• For artificial spawning of wells having regard to
  special reproductive features of species, must
  ensure a technical-material base specific and in
  accordance with different stages of this process.
• Technological system will be apportion depending
  on production capacity agreed by costumer, and
  will ensure by its capacity the spawning of
  minimum 10 families, in order to insure
  maintenance and conservation of genetic
  biodiversity of species.
• Correlate with the capacity for incubation,
  technological system will be framed by an
  ensemble of earthen ponds ponds for
  standing-wintering, ponds for pre-maturation,
  modules for standing and maturation of breeders,
  modules for incubation of embrionated eggs and
  modules for standing and growing larvae.

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• Ponds for pre-maturation, modules for maturation
  of breeders and modules for incubation of eggs
  have the same properties as the case of
  pikeperch.
• For standing and rearing larvae should be used
  PVC or fiberglass tanks with volume of about 1300
  l, fitted with proper fuel system, adjustment and
  discharge of water.

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DESCRIPTION OF TECHNOLOGY

• Technology for artificial spawning and rearing
  larvae of Silurus glanis involves travel along
  following stages
• Assurance of breeders stock
• Evaluation of phenotypic characters and sex
  determination
• Standing, pre-maturation of breeders
• Maturation of breeders
• Induction of sexual cells maturation
• Gathering sexual products
• Fecundation
• Incubation of sexual products in special
  installed enclosures
• Sampling and standing larvae in enclosure
  standings
• Sacking and transportation of larvae
• Rearing larvae up to 45 days.

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• Assurance of breeders stock.
• Wells breeders used in artificial spawning come
  from stocks reared in farms especially for this
  goal.
• For the establishment of breeders stock are
  chosen fish with age of 4 8 years and weight of
  6 10 kg.

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Morphological criteria used to determine 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
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• Hormonal treatment goes through after 24 hours
  from stocking of breeders in the station for
  incubation. For induction of sexual cells
  maturation on wells, it is used carp pituitary.
• Hormonal induction of females is made in two
  steps
• Step I 0.5 mg/kg of body weight for both
  females and males
• Step II 4 mg/kg of female body weight and 3
  mg/kg of male body weight.
• Before injection and gathering gametes breeders
  are anesthetized in a solution of 2-fenoxietanol
  (1 1000).

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• Gathering eggs and artificial fertilization.
  Method of harvesting is abdominal palpation,
  technology known as milking.
• Abdomen is gently massaged on longitudinal
  direction up and down, along axial line of
  abdomen, pushing eggs by the genital hole.
• From each female collect a single portion of
  eggs, about 160 200.000 eggs.
• 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 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 0.13 0.14 109
  spermatozoids/kg body weights.
• Artificial fertilization
• Fertilization is accomplished with mixture of
  sperm originating from at list 2 3 males. For
  fertilization of 100 g of eggs are required 2 ml
  of sperm.
• 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.
  Mixture is homogenized for 10 seconds, and then,
  after 2 minutes add another 25 ml of activating
  solution and eggs are spread on nytal frames with
  help of a feather. After another 5 minutes,
  fertilized eggs are bringing in Nucet hatcheries
  for incubation.

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• Sampling and standing larvae
• Sampling of hatched larvae is made continuously
  on cushion of water, in individual tanks for
  gathering. Gathering tank is fitted with a nytal
  cage having mesh size of 0.3 0.5 mm to
  constrict the larvae.
• The constricted larvae are sample with the help
  of paddles and placed in special enclosure for
  standing. The operation is carried out
  continuously until the end of hatching. Counting
  larvae is accomplished directly at the time
  collection.
• Stocking density will be of 40 60 ex/l. flow of
  water in standing tanks will be adjusted to 5
  l/min. Larvae will stay on these enclosures a
  period of 5 7 days up to resorption of yolk.

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• Growth of larvae up on achieving adult-like
  phenotypic characters
• Stocking rate
• Larvae achieved from each female are stoked
  independently on rearing enclosures.
• Stocking rate is 1500 ex/m3 and is determined
  taking into account technological losses for
  rearing phase which in general are estimated on
  30 .
• The height of water column in rearing enclosures
  is adjusted to 20 cm.
• Technological water from enclosures will be
  assessing physic-chemically by determination of
  temperature, pH and oxygen.
• The flow of water supply in enclosures for
  pre-maturation is set at 5 7 l/min.

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• Feeding
• Rearing of larvae up to outlining phenotypic
  characters conformable 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 and then a composite diet
  composed of natural food and forage.
• Feeding with natural food is achieved with very
  small zooplankton. The diet is supply with
  blended yolk of egg.
• Feeding of larvae using natural live food in a
  composite diet with forage will imply the use of
  following feeding schedule that will allow
  gradually passing to a feeding based exclusively
  on forage
• first 5 days 85 zooplankton, 15 forage
• next 5 days 60 zooplankton, 40 forage
• next 5 days 50 zooplankton, 50 forage
• next 5 days 10 zooplankton, 90 forage.
• After that feeding will be assure only by forage.
• With the passage exclusively on forage, daily
  ration will be determined depending on
  consumption, percentage ranging from 4 to 20 of
  batch weight.
• During rearing time preventive treatments are
  made for mix bacteria and ichtyophtiriosis these
  disease are symptoms abatement, bleaching tail
  with necrosis and then fall of necrosis part of
  the tail. For treatment use oxytetracycline
  neomycin.
• For ichtyophtiriosis use malachite green combined
  with formalin.