الفهرس | Only 14 pages are availabe for public view |
Abstract This study aimed to evaluate the reproductive behavior of marine shrimp through studying the reproductive biolor, together with studying the reproductive performance such as spawning activity and quality together with the effect of season and size/age on such performance for the same population. Additionally, assessment of the performance of wild spent broodstock induced to remature and spawn by unilateral eyestalk ablation and serotonin injection. The entire specimen (652 individuals for the biological study and over 136 individuals for the reproductive performance) were obtained from Abu Kir Bay and the study was carried out in the invertebrate laboratory at the National Institute of Oceanography and Fisheries (NIOF) in Alexandria and Faculty of Veterinary Medicine, Alexandria University. Reproductive Biology By external examination of ovarian color and size five ovarian maturity stages were recognized for P. jczponicus females. These stages were immature, early maturing, late maturing, mature and spent The spawning season of P. japonicus was determined following the seasonal relative frequency distribution of different maturity stages jas well as the gonadosomatic index of different months and different aturity stages. Accordingly the spawning season ofF. japonictis was nd to be intensive during the period from April to October with a -or peak in May-June and another relatively minor one in september- October. The population structure of female P. japonicus during the main ipawning (spring: April-June) covers a range of sizes; the smaller sized males (<55mm CL, < 150mm TL) present in spring derived from ng in the previous season. These (small cohort) prawns are < 12 |