Kaptai Lake

Bangladesh is enriched with extensive potential water resources distributed all over the country. Kaptai Lake is one of the most important freshwater body which is the largest man-made freshwater resource in the South-East Asi a as well as in Bangladesh. The Kaptai Lake was created by damming the river Karnaphuli near Kaptai of Rangamati district in 1961. This lake was primarily created for hydro-electrical power generation.

Kaptai Lake  the largest man-made freshwater body in Bangladesh. Though created primarily for hydroelectric power generation, it contributes to produce significant quantity of freshwater fishes, navigation, flood control and agriculture, etc. The reservoir was created by damming the river karnafuli near kaptai town in the CTG(Latitude 22º09´N and Longitude 92º17´E). The lake is confined within the hill district Rangamati and embraces the upazilas of Rangamati Sadar, Kaptai, Nannerchar, Langadu, Baghaichhari, Barkal, Juraichhari and Belaichhari.

 Physical structure:

Kaptai Lake has ‘H’ shaped structure and two arms of this lake is joined near Shuvalong which is a part of Karnaphuli river.  Total surface area of Kaptai Lake is 68,800 hectare and average water depth is about 9 meters with maximum depth of 32 meters. The shoreline and basin of this water body are very irregular.

Geologically, the lower part of Kaptai Lake, in and around the Kaptai-Rangamati region (ie Kaptai Syncline), is composed mainly of yellowish brown, fine to medium grained, massive to cross-bedded sandstone with alternating shale and silty shale (Tipam Sandstone Formation) and the upper part is featured by yellowish brown, fine to medium grained, subangular to sub-rounded, moderately to poorly sorted, massive to thick-bedded and occasionally cross-bedded sandstone with quartz granules, pebbles, clay galls and contains well preserved leaf impressions (Dupi Tila Formation).

Fish and other fisheries items of Kaptai Lake:

Like other water bodies of the Bangladesh, diversified and many fish species and some other fisheries items are found in Kaptai Lake. Many scientist and organization recorded the fish and other fisheries items of Kaptai Lake in different times. ARG (Aquatic Research Group) (1986) recorded 49 indigenous fish species and 5 exotic fishes in this lake. Halder et al. (1991) recorded a total of 71 fish species including 5 exotic fishes and 2 species of prawn. A study by Chakma (2007) shows that 74 freshwater fish species and 2 prawn species are available in the Kaptai Lake.

 Fish production:

The Kaptai Lake continues to serve as a good and important source for fish production. Commercial exploitation of fish from Kaptai Lake started in 1965. From then considerable amount of fish are producing every year from this lake which is an  important part of the total inland water catch. Recent fish production from this lake are shown in the following table-

Year	Fish production (MT)	Production/Area (kg/ha)
2003-2004	7238	105
2004-2005	7379	107
2005-2006	7548	110
2007-2008	8248	120

At the start of commercial exploitation of fishes from Kaptai Lake, major carp were the dominant fish species contributing 60% plus production from this lake. But, now, production of major carp species in Kaptai Lake decreased much. In the year 2004-2005, caught fish species were Rui (Labeo rohita) 45 MT, Catla (Catla catla) 117 MT, Mrigel (Cirrhina mrigala) 26 MT, Kalbaus (Labeo calbasu) 189 MT, Gonia (Labeo gonia) 29 MT, Boal (Wallago attu) 26 MT, Aiye (Mystus aor and M. seenghala) 384 MT, Shol/Gazar (Channa straita and C. marulius) 46 MT, Chital (Notopterus chitala) 6 MT, Shingi/Magur (Heteropneustes fossilis and Clarias batrachus) 76 MT, Pholi (Notopterus notopterus) 45 MT, Bacha (Eutropiichthys vacha) 12 MT, Kazoli (Ailia coila) 70 MT, Tengra/Pabda (Mystus tengra and Ompok pabda) 39 MT, Baim (Mastacembelus sp.) 13 MT, Chapila (Gudusia chapra) 2085 MT, Kachki (Corica soborna) 3284 MT, Grass carp (Ctenopharyngodon idella) 5 MT, Silver carp (Hypophthalmichthys molitrix) 21 MT, Tilapia (Tilapia sp.) 224 MT and others 637 MT (FRSS, 2006). From the statistics, it is very conspicuous that production of major carps species decreased greatly whereas Chapila (Gudusia chapra) and Kachki (Corica soborna) contributed more than 50% Kaptai Lake production.

In the year 2007-2008, species wise fish production of Kaptai Lake was found as Rui (Labeo rohita): 69 MT, Catla (Catla catla): 171 MT, Mrigal (Cirrhinus cirrhosus): 80 MT, Kalbasu (Labeo calbasu), 149 MT, Gonia (Labeo gonius): 2 MT, Grass carp (Ctenopharyngodon idellus):1 MT, Silver carp (Hypophthalmichthys molitrix): 3 MT, Boal (Wallago attu): 60 MT, Air/Guizza Air (Sperata aor / Sperata seenghala): 437 MT, Pangas (Pangasius pangasius): 51 MT, Sarpunti (Puntius sarana): 3 MT, Shol/Gazar/Taki (Channa striatus/C. marulius/C. punctatus): 74 MT, Chital (Chitala chitala): 4 MT, Singi/Magur (Heteropneustes fossilis/Clarias batrachus): 19 MT, Phali (Notopterus notopterus): 66 MT, Bacha (Eutropiichthys vacha): 9 MT, Punti (Puntius spp.): 3 MT, Tengra/Pabda (Mystus tengra /Ompok pabda): 18 MT, Baim (Mastacembelus spp.): 8 MT, Chapila (Gudusia chapra): 2,459 MT, Tilapia/Nilotica (Oreochromis mossambicus/O. niloticus): 222 MT, Kachki (Corica spp.): 2,466 MT and Others: 1,874 MT (FRSS, 2009).

Production of exotic fishes from this lake got attention because fish like Tilapia considered threat to indigenous fish species. Fish harvested from Kaptai lake meets local demand and also supplied to other parts of the Bangladesh.

Kaptai Lake

Problems:

At present Kaptai Lake is suffering from many problems. Fertilizers and pesticides used in lake adjacent crop fields polluting lake water. Again, water level become reduced much than previous years. 

People living around the lake depends on the lake water for drinking, cooking, washing and breathing. Local fishermen also caught fish in this lake. To get more and sustainable production, proper and scientific management system need to be introduced for this lake. Also government and associated authorities should take immediate steps to make a good solution of existing problems of the lake.