Collection and storage of hypophyses
103. COLLECTION AND STORAGE OF HYPOPHYSES
Whenever possible, hypophyses (pituitary glands) should be collected from mature, freshly killed carp. They should then be dehydrated and stored. These dried hypophyses will be needed for the preparation of the hormonal extract to be injected into the carp breeders for inducing their maturation.
The head of the fish being firmly held vertically between two pieces of wood, proceed as follows: (a) draw a line perpendicular to the lateral side of the head from each eye; (b) place the centre of the drill at the meeting point of these lines; (c) adjust he drilling angle so that it equals 90°; (d) drill through the top of the skull, the brain and the base of the skull, down to the mouth cavity; (e) take out the drilling head together with the small cylinder made of bone and tissues. (2) Using a wooden finger fixed to the table, remove this cylinder from the drilling head. 3) Cut it in two, carefully lift the brain tissue (including the hypothalamus) lying on the base of the skull, and pick out the hypophysis with a forceps.
Place it in a bottle containing acetone, together with the other hypophyses collected on the same day.
These containers should be tightly sealed, using for example wax or paraffin. A label should be added, indicating the date of collection and the origin of the glands. Even in tropical regions, acetone-dried hypophyses can be stored for at least 5 years without refrigeration. The sealed containers should be kept either in a plastic bag or in a desiccator, in the presence of a water absorbent such as silica gel or calcium chloride.
TABLE 1. SELECTED DATA ON THE REPRODUCTIVE BIOLOGY OF COMMON CARP
First sexual maturity | ||||
Temperate climate |
Warm climate |
|||
Age, years | Males | 2 - 3 | 1 | |
Females | 4- 5 | 1 - 2 | ||
Weight, kg | Males | 3 - 4 | - | |
Females | 4- 5 | - | ||
Standard length, cm | Males | 25 - 30 | 15 - 20 | |
Females | 30 - 40 | 15 - 20 | ||
2. Spawning | ||||
Spawning water temperature, °C | at least 17 | |||
Optimum range temperature, °C | 22 - 24 | |||
Spawning behaviour | in groups, in fully inundated grassy areas | |||
3. Egg stage | ||||
Ovulation period in hour-grades (°C) | 240 - 260 | |||
Incubation period in day-grades (°C) | 60 - 70 | |||
Number eggs per kg carp body weight | 100 000 - 200 000 | |||
Number dry eggs in one kg | 700 000 - 1 000 000 | |||
Number swollen eggs in one litre | 80 000 -120 000 | |||
Diameter of dry eggs, mm | 1 - 1.5 | |||
Diameter of swollen eggs, mm | 2 - 2.5 | |||
4. Larval stage | ||||
Total length newly hatched larvae, mm | 4.8 - 5 | |||
Duration larval stage, day-grades (°C) | 60 - 70 | |||
5. Early fry stage | ||||
Total length early fry at first feeding, mm | 6 - 7 | |||
Size at first food, mm | 0.1 - 0.2 |
TABLE 2. SELECTED DATA ON THE ARTIFICIAL PROPAGATION OF COMMON CARP IN A HATCHERY
1. Broodstock management
Pond size: 0.5 - 1 ha
Stocking rate: 100 - 300 inc./ha
Feeding:
(a) during formation of dormant eggs: 50% natural food and 50%
artificial feeds rich in carbohydrates.
(b) after formation of dormant eggs: artificial feeds containing
30-40% protein.
2. Production of sexual products, milt and eggs | |
Water temperature, °C | 20 - 24 |
Sex ratio of breeders | 2F:1M |
First injection of females, | |
dried hypophysis mg/kg | 0.3 |
salt solution ml/fish | 0.1 |
Second injection of females, | |
dried hypophysis mg/kg | 3.5 |
salt solution ml/fish | 1.5 |
Single injection of males, | |
dried hypophysis mg/kg | 2.0 |
salt solution ml/fish | 1.5 |
Time between two injections of females, hours | 10 - 12 |
Time between 2nd injection females and ripening, | |
hour-grades °C | 240- 260 |
Minimum time necessary after injection males, hours | 6 |
Percentage of ripening females | 60 - 90 |
3. Artificial fertilization of the eggs | |
Quantity of milt necessary, ml/kg dry eggs | 10 |
Percentage fertilization success | 80 - 95 |
4. Incubation of the fertilized eggs | |
Water temperature, optimum °C | 22 - 24 |
Quantity of eggs in 7-litre jar | |
e.g. dry eggs, kg | 0.25 - 0.30 |
swollen eggs, litres | 1.5 - 2 |
Water flow, litres/minute | 0.6 - 2 |
Duration of incubation period, day-grades °C | 60 - 70 |
Malachite-green treatment, cone. mg/l. | 6 |
Percentage hatching success | 95 |
5. Rearing of larvae and early fry | |
Water flow, litres/minute | 12 - 15 |
Number of larvae in 200-litre jar | 500 000 |
Duration of yolk-sac stage, day-grades °C | 60 - 70 |
Duration of rearing in jar, days | 3-4 |
Percentage survival rate | 60 - 90 |
Number of early fry produced/kg dry eggs, thousands | 500 - 700 |
Size of first food, mm | 0.1 - 0.2 |