FISHING GEARS AND THEIR EFFECTS ON FISH DIVERSITY OF DEKHAR HAOR UNDER DAKSHIN SUNAMGANJ

Abstract

A study was conducted to determine the fishing gears used their catch composition, catch per unit effort and effects of fishing gears on fish diversity of Dekhar haor for the period of 12 months from September 15 to August 2016. It was estimated that 51 fish species were belonged to 9 orders under 21 families, 34 genera and 4 genuses. Among the threatened fishes vulnerable (13), endangered (9) and critically endangered (7) were found. The most abundant fish species in the haor were Macrobrachium malcomsonii (ichha), Amblypharyngodon mola (mola), Puntius ticto (titputi), Mystus tengara (tengra), Mastacembelus armatus (baim), Macrognathus pancalus (guchi baim), Nandus nandus (bheda), Glossogobius giuris (baila), etc. A total of 20 types of fishing gears under five major groups such as nets, traps, hooks and lines, wounding gear and fish aggregating devices (FADs) were recorded. During April to November/December, mainly ber jal, current jal, koi jal, jhaki jal, uttar jal, thela jal, khora jal, dharma jal, borshi, hand borshi, Katha fishery and different types of traps (dori, chai, plastic chai, gui, ucha, polo, ronga), hooks and lines (borshi and hand borshi), and wounding gear (koach) were used by the fishermen of the haor. With respect to fishing nets, the highest catch per unit effort (CPUE) 4.67 kg gear-1day- 1 was recorded in ber jal followed by bata jal, khora jal, dharma jal, uttar jal, current jal, koi jal and jhaki jal. The lowest CPUE 1.56 kg gear-1day-1 was obtained in thela jal. Of the traps the highest CPUE (2.3 kg gear-1 day-1) was recorded in borshi followed by polo (1.75 kg), ucha (1.62 kg), hand borshi (0.6 kg), koach (0.36 kg), dori (0.2 kg), bhair (0.17 kg) and ronga (0.12 kg). The lowest CPUE (0.09 kg gear-1day-1) was found in plastic chai in the haor. It was observed that huge amount of fishes were caught by ber jal prior to breeding period and the rare species are damaged through this bulk catch and finally disappear from the haor. Order-wise catch composition of fishes in the haor Cypriniformes (30%) was the most dominant order followed by Perciformes (22%), Siluriformes (22%), Synbranchiformes (8%), Beloniformes (8%), Osteoglossiformes (4%), Clupeiformes (2%), Tetraodontiformes (2%) and Crustaceace (2%). On the basis of species composition, seine net, gill net, cast net, lift net, push net, plastic chai, chai, dori and hand borshi were considered as non-selective gears while koi jal and borshi were found as selective gears. Seine net (ber jal), gill nets (current jal) and lift nets (khora jal) were found to be most detrimental for the fish species among the recorded gears. The study reveals that the availability of fishes of the haor is drastically reduced in every year due to manmade (indiscriminate use of different types of gears, insecticides, pesticides, using complete dewatering technique for catching fish) and natural calamities (drought, flash flood, sand deposit from upstream rivers and canals, rainfall variations, temperature fluctuation). The present situation of fish catching in the haor continues in such a way, the haor would be barren of all kinds of fishes and other organisms. The people living around the haor should come forward to stop the operation of harmful fishing gears round the year. The government and other organizations should take immediately initiatives to protect the biodiversity, ecosystems and mother stocks of the haor for the greater interest of the nation.