Studies on traditional methods of wild giant freshwater prawn seed collection and their potential impact on the aquatic ecosystem

Abundance and seasonal variation of Macrobrachium rosenbergii seed in the natural water bodies such as creeks and rivers have great influence on freshwater prawn farming. Freshwater prawn farming is still heavily dependent on wild seed in India. Due to traditional collection methods and poor handling, there is immense destruction of non-targeted species of shell fishes and fin fishes. The present study was conducted on Amba river near Wakan dam in Raigad district of Maharashtra. The wooden bamboo strip traps of size 60 cm long with 15 cm outer circumference, locally known as “Bagala” or “Bokshi”, were used to collect the wild seed. Approximately, 40 to 70 number of traps were operated by 22 fishermen per day for 4 to 5 months. Mortality of M. rosenbergii seed reported during collections was 2 - 3 %, while fish seed (10 - 12%) collected along with prawn seed was used for consumption. It was observed that 53.47% of commercial prawn species was constituted by seeds of M. rosenbergii, 35.40% of non-commercial prawn species and 11.01% of other fishes. Seeds of M. rosenbergii was used for culture, while non-commercial prawn species and other fish seeds were used for local consumption or destroyed during collection. It is therefore necessary to segregate only M. rosenbergii seed and release local species of prawns and fishes back into the natural water bodies to conserve the aquatic fauna.