POPULATION STRUCTURE OF STURGEONS IN THE COASTAL WATERS OF THE MAZANDARAN PROVINCE, SOUTH CASPIAN SEA

Diversity, distribution, catch per unit effort (CPUE) and population structure of sturgeon stocks in the Iran coastal areas of the Caspian Sea waters less than 10 meters deep was studied during 2003-2005. We also recorded total length and weight of all sturgeon specimens in five regions which was done by gillnet with mesh sizes 26, 33, 40, 60, 100, 150 mm during seasonal sampling from autumn 2003 to summer 2005 in the south of the Caspian Sea. Totally, 301 fish were sampled in 2003-2004 including Acipenser persicus (244) A. stellatus (35), A. nudiventris (13), and A. guldenstaedti (9). A total of 412 fish were sampled over the years 2004-2005 of which 369 were A. persicus, 14 were A. stellatus, 7 were A. nudiventris, 21 were A. guldenstaedti, and one was Huso huso. In 2003-2004, the CPUE for A. persicus, A. stellatus, A. nudiventris, A. guldenstaedti were 4.07, 0.58,0.22 and 0.15 respectively, whereas for A. persicus, A. stellatus, A. nudiventris, A. guldenstaedti, and for Huso huso the CPUE was 6.15, 0.23, 0.12, 0.35 and 0.02 respectively. In 2003-2004, the mean total length was 26±10.86 cm A. persicus, 49.7±14.5 cm for A. stellatus, 38±13.79 cm for A. nudiventris and 43.1±10.25 em for A. guldenstaedti. In 2004-2005, the mean total length was 21.0±18.56, 5205±25.53, 30±13.09, 23.37±12.2 and 50 cm for A. persicus, A. stellatus, A. nudiventris, A. guldenstaedti, and Huso huso respectively.