An investigation on sturgeon fish migration in Sepidrud River

This study was conducted to assess migration potential of Sepidrud River which was naturally used for migration in past. The investigation included an area from the mouth up to 30 km covering part of river's potamon region. During 35 days, starting from 21th April to 25th May 1993, 54 samples of Acipenser guldenstadti, 151 individuals of Acipenser persicus and 178 Acipenser stellatus were examined. These comprises 14.1%, 39.4% and 46.5% of the samples respectively. Average total length of these sturgeon fishes were 127 cm, 143.7 cm and 151.1 cm respectively, the sex ratio (M/F) of these migratory fish was 1.4:1, 0.5:1, 0.59:1 for A. stellatus, A. guldenstadti and A. persicus respectively. The migration occurred despite of the shallowness of the river's mouth, caused by a sand-clay barner deposits and despite illegal fishing during migration period. It is recommended that with regulation of water level have optimum water flow by Manjil dam and with a total ban of sturgeon fishing throughout the river especially at the mouth of the river and during spawning season (March - May) there still would be hope for a good number sturgeon spawning fishes to migrate into Sepidrud River