Abstract
A study was conducted to provide an overview on the aquatic resources and fisheries status of the Chalan beel and to identify the opportunities for improvement of the existing fisheries management strategies, focusing on fish biodiversity conservation. Sampling for CAS, FES and water-sediment was carried out at the Gumani, the Katagang and the Baral sites. GIS study, interview and FGDS were conducted in ten upazilas in and around Chalan beel. A total of 36 triplicate samplings yielded 5,814 finfish individuals of 106 species belonged to 10 orders under 31 families and 71 genera Among the threatened fishes (as described by IUCN, 2000) critically endangered (6), endangered (20), vulnerable (10) and data deficient (18) were found. The most abundant fish species were punti (Puntius sophore and Puntius ticto) followed by chanda (Chanda nama and Parambassis ranga), tengra (Mystus vittatus) and chapila (Gudusia chapra). The abundance of several species showed decreasing trend from 2007 to 2008. In the study, 21 rivers, 93 beels and their floodplains, 12,817 ponds and 214 borrow pits were documented inside the Chalan beel. Most of the rivers experienced dry to isolated pools (67.82 +3.67%). The number of professional fishers has declined by 58% between 1982 and 2008 and the fishers left the profession due to much decreased fish availability in the beel as a result of very low fish catch and falling income. Assessment of the habitats condition through RS images and GIS tools were performed using MODIS AQUA (250 m). NDVI and Isocluster images were prepared using NIR, MIR & blue bands for interpreting and analyses. The images interpretation showed a trend of water receding from wet to dry season and from year to year. The occurrence of moderate and high vegetation was comparatively higher in 2002 image than in 2008 image. A total of 34 different types of fishing gears including nets (11), traps (11), hook and lines (4), wounding gears (4), FADS (3) and hand-fishing (1) were observed. Seine nets were the dominant gear followed by gill nets and set bag nets. The mean CPUE of different fishing gears varied widely ranging from 2.04 to 48.99 kg unit1 day. The average total annual fish production of the beel was 12,566.57 MT having average fish production of 281.86 kg ha1 during the study period. The fish production was 26,990, 18,700, 15, 460 and 12,217 MT in the year 1982, 1992, 2002 and 2006, respectively. Crop farmers applied 2.76 kg pesticide ha crop1 and average annual chemical fertilizers usage was more than 1,25,000 MT in the Chalan beel. The pesticide usages have been increased from 401 MT in 2001 to 536 MT in 2005. A total of 108 and 143 large to minor scale fish mass mortality incidences were recorded with estimated fish damage of 2,117 and 2,980 kg respectively during the study period. The loss could be many folds higher, if the habitat destruction and the production loss due to the mortality of egg, fry and fingerling could be considered. The mean values of water depth, water temperature, transparency, pH, total alkalinity, conductivity, TDS, NH3-N, NO3-N, PO4-P, sediment pH, OM(%), TN(%), Available-P and exchangeable-K in Chalan beel observed as 214.73±152.22 cm, 27.68+4.26 °C, 123.95±82.14 cm, 9.7±0.47, 137.83+42.35 mg 1, 307.52±147.88 us cm 183.05±89.91 mg11, 0.27±0.39 mg11, 0.09±0.07 mg11, 2.01±2.53 mg 1, 7.21+0.35, 2.59±0.52 %, 0.09±0.04 %, 5.43±3.60 Meq. (100g)"', 0.43±0.14 Meq. (100g) respectively, which were within the suitable range for most of the inland fishes of Bangladesh. If present trend of fish catching of Chalan beel legally and illegally continues without proper management and control measures, then one of the most valuable aquatic resources of Bangladesh - the Chalan beel would soon be empty of all kinds of fishes. It is the obligation of concerned GOS, NGOs and the people of the country to control the gear efficiency in the Chalan beel, stop the illegal use of harmful pesticides and provide alternative livelihood options to the resource-poor fishers of the beel along with other measures for sustainability of the Chalan beel - a major fish reservoir of the country.