ANNUAL MIGRATION OF THE GANGETIC DOLPHIN AND THE FISH TENUALOSA (HILSA) ILISHA: CORRELATION OR COINCIDENCE? A REPORT FROM THE BARAK RIVER OF ASSAM, INDIA

摘要

The present article highlights that migration of the fish Tenualosa (Hilsa) ilisha is a key determinant in the seasonal migration of the Gangetic dolphin. The dolphin follows the fish in the early monsoon to move upstream. However, it is probable that the dolphins don't follow T. ilisha while migrating. Nevertheless, it may be stated with certainty that the seasonal migratory preference of both these species is quite similar: both migrate upstream in the early monsoon and retreat in the post-monsoon. However, the fish returns to the sea and the dolphin retreats to the main river channel, or at most, the brackish waters. Thus, the present article reveals a trend in the seasonal migration of the dolphin in the Barak river system, which has implications in the conservation of the species as well as the fish.