نوع مقاله : مقاله پژوهشی
نویسنده
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسنده [English]
The research project was implemented to obtain bio-normative of artificial spawning of Esox lucius and rear fries until fingerling size in earthern ponds. The artificial spawning occured in 4 stages, totally 96 brooders (32 females and 64 males) were used for the experiments. The pituitary gland hormon of common carp was injected at 4-7 mg per kg of body weight in each dose to the spawner females. The water temperature during spawning was 8-150C and the time of artificial spawning started from 4 of February to 20 of March. The maximum weight of brooder was 4 kg and the minimum 0.75 kg; the oldest female fish brooder was 6 years old and the male 5 years; the minimum age for both sexes was three years. The spawning took place both by natural state in earthern ponds and also by eggs extraction and fertilization. The quantity of eggs extracted from female spawner composed between 10-20 percent of the body weight. There was no significant differences between one and two step hormon injections. The injected female brooder was ready for artificial spawning 48-74 houre later Mean incubation period lasted 120 degree days and yolk sac absorbtion lasted 160-180 degree days. The eggs stickness was rather high and the rate of fertilization fluctuated between 45-85%. One gram dry eggs contain 90-150 ovum with 1.5-2 mm diameter, and swelled eggs were 70-85 pieces with 2.5-3.5 mm diameter. Absolute, relative and working fecundity calculated 22400-112000, 19760-36920and 5200-67400 eggs respectively. Larvae feeding, after yolk sac absorbtion, was performed with a solution of dry milk and soya bean juice. The feeding first was conducted with soya bean juice and Artemia nauplius in earthern ponds. After wards the natural productions of the pond, having been enriched with chicken manure, were used. The survival rate, from larvae to fingerling size, was 20-22% during 50 days culture period. During this time the fly grew to 7.4 gr with 8.5 cm length, in average.
کلیدواژهها [English]
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