Credit: Roman Aszkiełowicz (Poland)
Review: Roman Aszkiełowicz and Abdel Rahman El Gamal (Founder of the website)
The hormone used in this given practice is the Human Chorionic Gonadotropin (HCG) using a single injection of 300IU/kg of female body weight (the dose can go up to 400 IU/kg). The hormonal application synchronizes the maturation process, and hence enhances the spawning effectiveness.
As shown in one of the images, the female has been anesthetized prior to stripping using etomidate.
The relative fecundity in pike perch is 170-230 eggs/g of body weight. Pike perch eggs are small with a diameter of 0.6-1.0 mm for unhardened eggs increasing to 0.0-1.6 mm for the hardened ones.
A 10-kg female produces around 2 – 2.2 million eggs which are fertilized by sperm taken from live males as done in this given case.
In order to remove the adhesiveness prior to incubation, eggs are placed in a tannin solution of 0.5-1.0 g/l of water for a period of 5 min.
Fertilized eggs are incubated in standard Weiss jars of a 7-l size furnished with bottom water supply of about 3 l/min. In fact, water supply is low at the beginning of egg incubation (0.5-1.0 l/min) while increases as incubation progresses reaching about 4.0 l/min). A typical 7-l Weiss jar can accommodate around 2 liters of eggs. The incubation period is determined according to the degree-day which is (80-120 °D) in pike perch and hence the incubation at 20 C as in the present case was 3.5 days ending by a hatchability of about was 90%.
The broodstock were caught from the wild whereas males reach sexual maturity at 2-3 years, while females require 3-4 years to reach their sexual maturity.