Fisheries in Trans-Himalayan Region: prospects for fish culture in Hill Districts of Bangladesh. (by M.A. Aziz and M.A. Hossain)

M. A. Aziz¹ and M. A. Hossain^2
1Ministry of Fisheries and Livestock, Bangladesh Secretariat, Dhaka, Bangladesh
²Bangladesh Fisheries Research Institute, Mymensing W-2201, Bangladesh

ABSTRACT

The hills of Bangladesh contain a number of rivers and streams, and also a large reservoir called Kaptai lake. Kaptai lake fish stocks have been overexploited and require serious management effort through stocking and introduction of aquaculture in cages and pens in order to fully utilize the lake fishery potential. Nevertheless, the presence of Kaptai lake has resulted in an increase in per caput fish consumption by the hill people, although much of the fish catch is still delivered to distant markets. Further potential for increasing fish production is offered by streams and rivers where cage culture could be introduced. In the mid-1990s a project "Fish Culture Development (in hills) and Extension" created 11.5 ha of nursery ponds and 92 ha of other water bodies by modifications of creek flows and construction of small dams, and these were brought under fish culture. Training of farmers in aquaculture and fish farmer refresher courses were given special attention under this project. The only cold water fish species now present in Bangladesh is mahseer (Tor putitora) which has been introduced from Nepal.

1. INTRODUCTION

While geographically Bangladesh lies at the foot of the Himalayas, most of her territory belongs to floodplains formed by silt carried down by the Himalayan rivers. Bangladesh is the biggest delta of the world. Her geology, climate, flora and fauna are greatly influenced by the Himalayas. The great mountains shield the country from northern cold and winds, help monsoon precipitation and provide snow-melt flow in her rivers during dry season. Yet, Bangladesh indeed is very different from the Trans-Himalayan region geologically, geographically, climatically and in biodiversity. More than 90% of her territory consists of floodplains which are elevated only a few meters above the sea level. It is feared that due to the greenhouse effect leading to melting of ice at the poles and peaks of high mountains such as Himalayas, a large part of Bangladesh may become submerged by sea water. Due to the shortage of hills and absence of high mountains, Bangladesh has no true cold waters. During the coldest period of time the temperature seldom drops below 15°C. Only very few fish species such as mahseer can be considered to have affinity to cold waters. Bangladesh imported mahseer from Nepal several years ago and they are doing fine under Bangladesh conditions both for seed production in hatcheries and grow-out as food fish in farms.

Bangladesh is a rice and fish eating nation. The main source of her animal protein comes from aquatic sources, mainly from fish and crustaceans. With the expansion of population and the increasing needs for more cereal-based foods, high yielding varieties of rice production have been promoted since the 1960s. This has successfully raised food grain production and made Bangladesh self-sufficient in carbohydrate based foods but at the same time it has led to a serious decline in wild fish production from open inland waters due to irrigation use of water, pesticides and fertilizers.

2. FISH AND FISHERIES

Biodiversity of aquatic animals including fish in open inland water bodies is threatened and several indigenous fish species are either extinct or are on the verge of extinction. A list of the threatened riverine and floodplain species of fish in Bangladesh is given in Table 1.

Table 1

List of threatened riverine and floodplain species of fish in Bangladesh

To increase fish production through aquaculture and to improve livelihood of the rural population several exotic fish species have been imported to Bangladesh since the 1950s. Among them tilapia was not initially appreciated but is now gaining popularity as a culture species among the rural people. Exotic fish species introduced to Bangladesh for the last five decades are listed in Table 2.

Table 2

Freshwater fish introduced to Bangladesh during 1950-2000

Some of the imported fish species are well adapted ecologically under local conditions and can be seen in fish markets. Among those common carp, pangash, tilapia, silver carp, grass carp, silver barb, mirror carp and bighead carp are an important component of marketed fish. However, it is still open to discussion whether all those exotic species were actually needed. Some of the imported species have been replacing some of the indigenous species from their natural habitats. It was found that polyculture of silver carp with Indian major carps seriously hampers the normal growth of catla (Catla catla), although catla is known as a very fast growing fish in Bangladesh and fetches a relatively high market price.

Traditionally a big segment of freshwater fish catch in Bangladesh used to come from open freshwaters. However, destruction of natural fish habitat, overfishing, environmental degradation, lack of proper management have led to a decline in catches. To some extent the loss is being compensated by the production from the growing aquaculture. This requires supplemental feeding and fertilization, and fish culture with low-cost carbohydrate-based supplemental feeding is gaining popularity in the country. The only exceptions are the Thai and African catfish which need animal protein rich diets. Due to the fast growth and high market price of the the Thai catfish, its culture is booming in rural areas. African catfish introduced to Bangladesh during 1987-88 has already earned a bad name and thus is banned, but it has already entered the ecosystem and will be difficult to eradicate as the species can breed naturally in closed and open water bodies. While aquaculture in plains of Bangladesh is expanding, the three hill districts and some parts of the northern and north-eastern hilly areas have not yet developed culture-based fisheries.

The three districts of Bangladesh lie in the south-eastern part of the country adjacent to the Indian hilly states and Myanmar. This area is inhabited by ethnic minorities. The northern tip of this area starts from the Indian state of Tripura and extends southward to the Bay of Bengal. Four rivers, i.e. Feni, Karnaphuli, Shangu and Matamuhori, and their tributaries carry water from hills to the Bay of Bengal. These rivers also created four valleys. Hill dwellers of Bangladesh produce part of their own food through shifting agriculture. They have not yet started fish culture. The biggest man-made closed water body in Bangladesh, Kaptai lake (reservoir), is situated in Rangamati, one of the hill districts. In 1961 a hydroelectric dam was constructed which created Kaptai lake which covers 68 000 ha during monsoon, and 58 000 ha during the dry season. The annual catch amounts to approximately 5-6 thousand tons. But the fish captured from this reservoir are not consumed locally, as most of it goes to big cities. Before the construction of the reservoir the per caput fish consumption in the area was far less compared to the present situation. Still, the per caput fish consumption in the hill districts is lower than in the rest of the country. Kaptai lake fishery is managed by the Bangladesh Fisheries Development Corporation (BFDC). The reservoir suffers from overfishing, and stocking the lake by BFDC has not resulted in an increase in fish production due to the lack of enforcement of fishing regulations.

Fish culture in Kaptai lake as well as in other waters of the three hill districts has good prospects. There are many creeks, where with little modification in their natural flow pen and cage culture could be introduced. In the valleys there are many small ponds and impoundments which could be used for aquaculture. During the mid 1990s the Government of Bangladesh encouraged aquaculture in creeks, ponds and lakes of the hill districts. Under the project named "Fish Culture Development (in hills) and Extension" 11.5 ha of nursery ponds and 92 ha of other water bodies were created by modifications of creek flows and construction of small dams, and these were brought under fish culture. Training of farmers in aquaculture and fish farmers refresher courses were given special attention under this project.

The Department of Fisheries of Bangladesh is trying to modernize fish culture activities in hill districts and provides extension. The Bangladesh Fisheries Research Institute is trying to develop cage and pen culture in Kaptai lake and hilly creeks. Low-cost feed development for cage culture is also an aim of the Institute. The Bangladesh Fisheries Development Corporation is trying to improve overall production of fish from Kaptai lake by selective stocking of Indian major carps. However, community participation is needed for the success of the stocking programme. Integrated farming of fish-cum-poultry, fish-cattle-poultry or fish-livestock-agriculture has good prospects in hill districts. Self-employment of hill people through integrated farming will not only improve economic conditions of hill dwellers but will also improve their nutrition

Table 3

List of indigenous fish and shrimps present in hill districts, including Kaptai Lake, Bangladesh

A list of indigenous fish for the hill districts, and especially for the Kaptai lake (Table 3), includes 66 indigenous species of fish and two species of shrimps. Besides these indigenous species some of the exotic fish species introduced to Bangladesh entered the hill districts. These are common carp, Thai silver barb, grass carp, Thai catfish, African catfish, tilapia and GIFT.

Not all fish and shrimp species listed in Table 3 are commercially exploitable, nor does each one have a good aquaculture prospect. Based on the present status and past performance, some culturable fish/shrimp in hilly areas are listed in Table 4.

Table 4

Culturable fish and shrimp in hill districts

Integrated natural resource management is a prerequisite for improving the quality of human life both on plains and in hills. The Chittagong Hill Tracts Region Development plan, submitted for ADB financing, is a right step towards the said goal. The project has components to improve the nutritional standard of hill people through increased fish production by open water management, pen and cage culture. The rivers and creeks of hill tracts of Bangladesh are good sites for aquatic biodiversity and natural spawning ground for some important commercial aquatic species. Selected fast growing species with low-cost diet may dramatically increase production of fish from Kaptai lake through pen and cage culture. Supplemental feed used in cages will indirectly help increase fertility of lake water. Pen culture and cage aquaculture can be extended to other hilly rivers and creeks of hill tracts. Cage and pen material production using local resources may be encouraged to lower the cost. Recreational sport fishing in Kaptai lake related to expanding tourism industry may be encouraged to develop facilities which will generate income for local people.