The Biobrio 11(3 & 4), 2024

Analysis of gill net selectivity on Labeo rohita in Kosi River of Madhepura, Bihar

Manoj Kumar & Arun Kumar

ABSTRACT:

In this study Analysis of gill-net selectivity for Labeo rohita in the River Kosi was estimated. Fishermen are using small mesh size gill net and capturing immature fishes. Study of Length at first maturity has been carried out to prevent the catch of immature fish. Traditional fishing was performed by using gill-net with 90 mm, 110 mm and 140 mm mesh-size during February, 2023 to October 2023. From the Kosi River tributary, a total of 630 specimens of L. rohita were caught by gill-net during the study period. Mean total lengths were calculated as 25.7 ± 2.7 cm, 32.2 ± 2.78 cm and 36.33 ± 4.69 cm for 90 mm, 110 mm and 140 mm mesh sizes gill-net respectively. Selectivity analysis indicated an optimum catch length of 290.50 mm for the 90 mm mesh size, 368.26 mm for the 110 mm mesh size and 390.89 mm for the 140 mm mesh size gill-nets. The predominant species was Labeo rohita (57%) followed by Catla catla (22%), Cirrhinus mrigala (16%) and Cyprinus carpio (5%) with respect to the total landings. The cast net fishery consists of five species being the Murrel (Channa sp.), Tilapia (Tilapia mossambicus), Rohu (Labeo rohita), Mrigal (Cirrhinus mrigala) and Catla (Catla catla) whose mean Catch Per Unit Effort (CPUE) was found to be 50-60 kg per day. The catch percentage of L. rohita by 90 mm, 110 mm and 140 mm mesh size gill-net were 36.68%, 41.20% and 23.22% respectively. The majority of fishes caught by these three-mesh size gill-net were found to be matured. Therefore, 110 mm mesh size were suitable for the sustainable fisheries of L. rohita in the River Kosi in Madhepura district of Bihar.

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