The production of the 'giant fresh water prawn' the biggest fresh water prawn in the world in 1975 was 429 tons
KOTTAYAM: Production of Kuttanandan Konchu or the giant freshwater prawns in the Vembanad Lake has touched an all-time low.
It has been reduced to 14 tons in 2014-15, from 18.04 tons in 2013-14 and 47.4 tons in 2012-13.
The latest study of the Regional Agricultural Research Station (RARS), Kumarakom, attributes the sharp fall to operational time schedule of the Thanneermukkam barrage and the absence of a scientific ranching programme.
The mother prawn is kept in captivity during the breeding season and the offspring reared in a nursery. When they attain the size of a juvenile prawn, they will be released into the lake.
Among other reasons are pollution, capturing mother prawns during breeding-migration and disruption of physical and biological connectivity with coastal waters.
The closure of the Thanneermukkam barrage during the post-monsoon months for rice farming in Kuttanad is identified as the prime reason for disruption in breeding and migration.
"This is a serious issue affecting the biodiversity of the Kuttanad region. This should be rectified by scientific ranching and timely opening of the Thanneermukkam bund after February," said Dr Padmakumar, its former director.
Construction of a fish ladder across the barrage could be a permanent solution for free migration of the species even during the current phase of construction under the Kuttanad package but that has not been accepted so far.
Sources say the migration of the mother prawns from the southern side of the bund in the month of October and November and the return of younger ones to Kuttanad during February-March have also been a major reason for the fall.
They will come back to Kuttanad during January when the bund is closed for rice cultivation. It prevents breeding.
Production of the biggest freshwater prawn in the world, which was 429 tons here in 1975, was reduced to 39 tons by 1989-90.
The ranching was first carried out effectively by the RARS in 1999, resulting in an increase in production.