Condition factor, annual mortality and survival rates of Great sturgeon Huso huso Brandt, Persian sturgeon Acipenser persicus Borodin, and starry sturgeon Acipenser stellatus Pallas in Iranian waters of theCaspian Sea

A total of 56 pectoral fin spine of Great sturgeon, Huso huso, ranging in fork lengthfrom 84 to 255 cm, 147 pectoral fin spine of Persian sturgeon, Acipenser persicus,ranging in fork length from 62 to 203 cm, 69 pectoral fin spine of starry sturgeon,Acipenser stellatus, ranging in fork length from 83 to 173 cm, were sampled to assesstheir condition factor, annual mortality and survival rates in Iranian coastal waters ofthe Caspian Sea. The condition factor were significantly different between the sexesof Great sturgeon and Persian sturgeon (P<0.05) and larger in females than that ofmales, whereas it was not significantly different between the sexes of starry sturgeon(F=0.49, df=1, P = 0.83). The annual mortality rates were calculated for males (47%,53% and 66%) greater than females (37%, 36% and 55%) in studied species,respectively. Also, the survival rates were estimated 63, 64 and 45 percent for femalesand 53, 47 and 34 percent for males for Great sturgeon, Persian sturgeon and starrysturgeon, respectively. The results revealed a declining in size of studied speciescompared to previous studies that may be resulted due to fishing pressure anddegradation of environmental conditions. The vulnerability of males in compare tofemales maybe due to spawning migration and returning to spawning sites at youngerages.

Keywords:

Pectoral fin spine , Biometry , Longevity , Mortality , Age