Tagged Hilsa Fish Recovery shows a Migration of 225 Kms in River Ganga

The ICAR-Central Inland Fisheries Research Institute, Barrackpore, Kolkata in association with the National Mission for Clean Ganga (NMCG), Ministry of Jal Shakti, Government of India is carrying out the Hilsa, Tenualosa ilisha Fisheries improvement in the River Ganga since 2020. The construction of Farakka Barrage in the River Ganga during 1975 has significantly impacted the Hilsa Fisheries. The production touched down to zero in the middle stretches of River Ganga (Farakka to Prayagraj, the study stretch).

To understand the current migratory pattern of Hilsa in the River Ganga, live fish of average weight of more than 250 Gms are being tagged with FloyT-bar anchor tags. A total of 391 tagged live Hilsa have been ranched in the River Ganga since November, 2020. On 6th October, 2021, a fishermen caught a tagged live Hilsa at Nimaitirtha Ghat, Baidybati, Hooghly District, West Bengal (220 47' 29.5" N; 880 20' 18.8"E) bearing Tagged No. - CIFRI1516 that was ranched on 1st October, 2021 at Farakka (24°48'14.93"N; 87°55'55.69"E).

The significant observation showed that the fish has migrated 225 Kms downstream from the ranching site within a period of 4 days 21 hrs. (117.3 hrs.). Of the 225 Kms of lower stretch of the River Ganga, 95 Kms stretch is a freshwater tidal stretch that shows the River stretch experiences tidal current. Negotiating the tidal current, the Hilsa migration speed was estimated as @ of 0.56 m/s. It has also been recorded a weight loss of 34 Gms during the period of migration (4 days 21 hrs.). This interesting result is of first its kinds to record in the migratory fish species in the country.

(Source: ICAR-Central Inland Fisheries Research Institute, Barrackpore, Kolkata)