A comparative analysis of feeding habits of sturgeon fish in shallow coastal waters of Mazandaran and Golestan Provinces, south Caspian Sea

Feeding habits of different genera of 354 sturgeon specimens (Acipenser persicus, Acipenser nudiventris, and Acipenser stellatus) were compared over the years 1999-2000 caught in the coastal waters less than 20 meters deep of Mazandaran and Golestan provinces, southern Caspian Sea. The caught specimens ranged 30-18cm in length. Overall, 16 families of food items were identified in the digestive system of the sturgeon specimens, of which 11 belonged to macro-benthos. The sturgeon fishes preyed on food items composed of Annelida 50.8%, Amphipoda 41.5%, small fish 4.8%, Decapoda 2% and Bivalvia 0.9%. Fish specimens shorter than 40 cm were mostly found feeding on shrimps, Polychaetes and gammarids. The 41—80cm length class mostly fed on shrimps, gammarids, Polychaetes, bivalves and smaller fish. Sturgeons longer than 80cm fed mostly on shrimps and smaller fish. Average fat coefficient for Acipenser stellatus was 0.43. A. persicus showed a fat coefficient 0.63 while that of the A. nudiventris was 0.97. Average stomach fullness was 8.3, for Acipenser stellatus, 100 for A. nudiventris and 165 for A. persicus. We found a similar diet between group one fish less than 40 cm long and group two with fish in the length class 41 to 80cm (r=0.7)