Investigation on sexual status of immature sturgeon captured from the south area of the Iranian waters Caspian Sea during 2004 - 2005

In this research، sex and sexual maturation stages of gonads in 253 sturgeon including 164 Acipenser persicus with mean weight 1210gr، 77 Acipenser stellatus with mean weight 1303. 3gr، 3 Acipenser nudiventris with mean weight 139gr، 3 Acipenser gueldenstaedtii with mean weight 126gr and 6 Huso huso with mean weight 4116. 6 gr that captured by using trawl from the south area of the Iranian coastal part of the Caspian Sea (from the Astara port in the Guilan province to the Turkman port in the Golestan province) during 2004- 2005 were studied. After biometry of fish، gonad samples were taken by biopsy and fixed in Buin،s solution. Gonads were studied histologically based on common methods and studied by using light microscope. Sexually، the results showed in Acipenser persicus، 104 (63. 4 %) were females and 60 (36. 6%) were males، in Acipenser stellatus 41 (53. 2 %) were females and 36 (46. 8%) were males، in Huso huso 66. 7 % female and 33. 3 % male، in Acipenser nudiventris 1 (33. 3%) was female and 2 (66. 7 %) were males، each 3 Acipenser gueldenestaedtii were females and in Huso huso 4 (66. 7%) were females and 2 (33. 3 %) were males. Totally، 153 (60. 5 %) was female and 100 (39. 5 %) was males. Also، 114 (45. 1 %) were at stage I، 45 (17. 8 %) were at stage I- II، 77 (30. 4 %) were at stage II، 11 (4. 3 %) were at II – III and 6 (2. 4 %) were at stage III of sexual maturity. Histological study of gonads showed that sturgeon populations at the south area of the Caspian Sea are juvenile، because they were at lower stages (I and II) of their sexual maturation.