Spermatogenesis, maturation, seasonal variations and spawning season of silver pomfret (Pampus argenteus, euphrasen) collected from the natural spawning grounds off the shore of Kuwait

摘要

A study on the reproductive biology of male silver pomfret, Pampus argenteus, was undertaken on fish collected from the natural coastal spawning grounds of Kuwait. A total of 215 fish were analyzed for the present studies from a total of 3454 males collected over the three successive spawning seasons. Grossly, testes were classified as mature or immature. The GSI was the lowest (0.13 +/- 0.02) in January while the highest values were recorded in June (0.72 +/- 0.04). Histologically, the testes were lobular and lobules contained many cysts. Each cyst was comprised of only one type of germ cells and contained either spermatogonia, spermatocytes, or spermatids. The cysts when matured released their contents (spermatids) in to the lobule lumen which were connected with the main sperm duct through anastomosing tubules. In the mature testis the spermatozoa arising from the spermatids filled the lobular lumen and the connected ducts. Sperms were also present in lobular lumen even in non-spawning individuals and winter months. These were residual sperms and were not actively removed from the testis as is the case in many other teleosts. This observation means that testicular regression was not characterized by phagocytosis or apoptosis of the residual sperms. In addition to the germ cells, interstitial cells of Leydig and intra-lobular Sertoli cells were also seen. Based on the collected samples, it appears that the spawning continues from June to October with a decrease in September, due to high temperatures. However, the peak of spawning was in June while a rather small peak was seen in October also.