river dolphins in bangladesh: conservation and the effects of water development

PROFILERiver Dolphins in Bangladesh:Conservation and the Effects of Water DevelopmentBRIAN D. SMITH*

P.O. Box 283Arcata, California 95521, USA

A. K. M. AMINUL HAQUEM. SHAKHAWAT HOSSAINANISUZZAMAN KHANNature Conservation Movement4, Sobhanbag, Mohammodia Super MarketRoom No. 125, G.P.O. Box 3413Dhaka-1207, Bangladesh

ABSTRACT / Ganges river dolphins (Platanista gangetica)are threatened in Bangladesh from the effects of dams, largeembankment schemes, dredging, fisheries bycatch, di-rected hunting, and water pollution. Visual surveys of thesection of the Jamuna River located between the divergenceof the Old Brahmaputra River and the confluence of thePadma River and the section of the Kushiyara River located

between the Bangladesh–India border and the confluenceof the Korangi River recorded a sighting rate of 0.13 sight-ings/km (mean group size 5 1.8 dolphins) and 0.08 sight-ings/km (mean group size 5 3.8 dolphins), respectively.These sections of river were considered to be priority areasfor investigation because several water developmentprojects have already been constructed and more areplanned for the areas. During the surveys we examined theremains of dolphins caught accidentally in plastic gillnetsand observed fishermen catching the fish species Clupi-soma garua using dolphin oil and body parts as a fish attrac-tor. Additional studies are needed to assess the status ofdolphins and effects of water development and fisheries by-catch. Feasibility studies should be conducted on designat-ing dolphin/fish sanctuaries and creating artificial habitat orenhancing existing habitat in eddy countercurrent scourpools to mitigate deleterious impacts. The environmentalrequirements of river dolphins reflect the needs of produc-tive and biotically diverse tropical rivers.

The Ganges river dolphin or susu (Platanista gan-getica; Figure 1) is known in Bangladesh as shushuk, orsometimes locally as sishu-, foo-, or hungmaach(maach 5 fish). This species is widely distributedthroughout the Ganges/Brahmaputra/Megna andKarnaphuli river systems in India, Bangladesh, andNepal (Kasuya and Haque 1972, Haque 1976, Jones1982, Mohan 1989, Shrestha 1989, Reeves and Brownell1989, Reeves and others 1993). The dolphin is classifiedas ‘‘endangered’’ in the IUCN Red List (Baillie andGroombridge 1996) and populations are believed to bedeclining as threats continue to grow (Reeves andLeatherwood 1994a).

The purpose of the present paper is to evaluate thenature and extent of threats to river dolphins inBangladesh, with particular emphasis given to theeffects of water development, and to recommend appro-priate conservation action. Field data were collectedduring dolphin surveys in the Burhiganga, Jamuna, andKushiyara rivers in October 1995 and April 1996.

River Systems of Bangladeshand Their Management

The alluvial channels and adjacent floodplains of theJamuna (Brahmaputra in India)/Padma (Ganges inIndia)/Megna river system occupy approximately 80%of the geographical area of Bangladesh (Figure 2) andsupport three quarters of the country’s human popula-tion (Dalal-Clayton 1990), estimated to be over 123million in 1996 (Famighetti 1996). High productivitywithin these environments is maintained by dynamichydrologic and sediment transport regimes. Duringnormal years, the annual flood cycle provides a nutrientand water supply essential for supporting productivefloodplain agriculture and fisheries.

The Jamuna River is one of the largest in the worldand accounts for more than 50% of the total water flowarriving to Bangladesh (BWDB 1992). During the dryseason, from November to March, flows in the Jamunarange from 3500 m3/sec to 6500 m3/sec. Beginning inApril, the melting snows of the northern slope of theHimalayas and Tibetan plateau, reinforced by monsoonrains in northeastern India, cause discharge in the riverto increase rapidly, sometimes peaking at over 100,000m3/sec (BWDB 1992). Large fluctuations in streamflow

KEY WORDS: Bangladesh; River dolphins; Water development; Pla-tanista; Fisheries bycatch; Flood Action Plan; Dams;Embankments; Barrages

*Author to whom correspondence should be addressed.

Environmental Management Vol. 22, No. 3, pp. 323–335 r 1998 Springer-Verlag New York Inc.

and non-cohesive silty bank and bed materials createextensive networks of braided channels and frequentlycause dramatic erosion events. River channel move-ments sometimes exceed 800 m/yr over a length ofseveral kilometers (BWDB 1992). During the monsoonseason, from June through October, extensive overbankspill, bank erosion, and shifts in mid-channel islandscalled chars are typical. Similar features occur in theother rivers of Bangladesh but at relatively smaller scales(FAP 21/22 1993).

The Padma River drains the southern slopes of theHimalayas. Dry season flows in the Padma are greatlyreduced by the Farakka Barrage, located 18 km up-stream from the India–Bangladesh border. Water flow isdepleted to such an extent that the main channel oftenturns into a series of small pools, resulting in a changeof ecological conditions from a lotic to lentic environ-ment.

The headwaters of the Megna River enter Bangla-desh as the Surma and Kushiyara distributaries of theBarak River, which drains the northeastern hills ofIndia. Together these rain-fed rivers have an annualdischarge of approximately 3515 m3/sec (Chowdhuryand Bhuiya 1990) with peak discharge reaching 20,000m3/sec (World Bank 1990).

The combined flows of the Jamuna, Padma, andMegna rivers form the lower Megna River, which isapproximately two and a half times the size of theMississippi River in the eastern United States (Rogersand others 1989). Eighty percent of the discharge in thelower Megna passes during the monsoon season, al-though discharge during this period is characterized bylarge fluctuations (Hossain and others 1987). Peakflows sometimes reach 160,000 m3/sec (World Bank1990).

The Chittagong hills in the southeast of the countryare drained by the comparatively small Karnaphuli,Sangu, and Matamuhari rivers. A high dam was con-structed on the Karnaphuli River in 1962, creating theKaptai reservoir, which flooded over 76,600 ha of forest

(Akonda 1989) and drastically altered ecological condi-tions in the 89-km stretch of river below the dam beforeit meets the sea.

Following floods in 1987 and 1988, which inundated60% of Bangladesh’s territory and affected 50 millionpeople, the World Bank was asked by the Governmentof Bangladesh to coordinate an action plan for floodcontrol (World Bank 1990). The original Flood ActionPlan (FAP) advocated the containment of major riversin Bangladesh by constructing an extensive series ofembankments along both banks and proposed to con-trol flooding and drainage of the land behind theembankments by using internal embankments to sur-round compartments or polders. The plan generatedgreat controversy, due to its extensive environmentaland social implications (see Dalal-Clayton 1989, Boyce1990, Pierce 1991, Sklar 1992, Custers 1992, Adnan andSufiyan 1993) and was subsequently reevaluated. Al-though still controversial, the current FAP ‘‘recognizesthat many of the earlier technical solutions for floodcontrol could have significant problems’’ (FPCO 1995)and emphasizes a more integrated approach, with‘‘particular attention being paid to environmental im-pacts and management’’ (K. Pittman personal commu-nication).

River Dolphins

Status and Distribution

Shushuk occurs in all major rivers of Bangladesh.Although no credible assessments of dolphin abun-dance are available, at a recent meeting of the AsianRiver Dolphin Committee, members expressed concernat the serious decline in dolphin populations reportedby the Bangladeshi members of the committee (Reevesand Leatherwood 1995). Shushuk is threatened fromincidental catch in fishing gear and, at least in someparts of Bangladesh, directed hunting (Pelletier andPelletier 1980, Reeves and others 1993), as well as

Figure 1. Shushuk surfacing with itsrostrum out of the water.

B. D. Smith and others324

damming and the withdrawal of surface water (Leather-wood and Reeves 1994a).

We conducted visual surveys for river dolphins dur-ing October 1995 and April 1996 of sections of theJamuna and Kalni-Kushiyara rivers. Surveys in theJamuna River consisted of 189.6 km (17.0 h) of searcheffort between the divergence of the Old Brahmaputra

and Jamuna rivers to slightly upstream of the conflu-ence of the Jamuna and Padma rivers during 22–25April 1996. This stretch of river has already beenaffected by construction of the Brahmaputra RightEmbankment and Jamuna Multipurpose Bridge Projectand will be affected by the Jamalpur Priority Project andBrahmaputra River Bank Priority Works. Surveys of the

Figure 2. Map of Jamuna/Padma/Megna and Karnaphuli river systems in Bangladesh showing water development projectsaffecting river dolphins.

River Dolphins in Bangladesh 325

Kushiyara River consisted of 113.0 km of search effort(15.2 h) between the Bangladesh/India border and theconfluence of the Korangi river during 7–11 October1995. This stretch of river has already been affected bythe Manu River Project and will be affected by theKalni-Kushiyara River Improvement Project and, if con-structed, the Tipaimukh High Dam in India. Theobjectives of these surveys were to confirm the occur-rence of dolphins and obtain rough indices of relativedensity.

Two to three observers searched for dolphins fromlocal motorized vessels. In wide channels of the JamunaRiver we followed a search path 100–200 m offshore ofthe river bank and arbitrarily alternated between sides.In narrow channels of the Kushiyara River, where wecould easily see a dolphin surfacing near the oppositebank, we followed a search path roughly in the center ofthe river while surveying in a downstream direction andapproximately 50 m from shore while surveying in anupstream direction. We recorded our position with aGlobal Positioning System (GPS), every 30 min, and atlocations of course changes and dolphin sightings.When we sighted dolphins, we remained in the area forat least 15 min to make best, high, and low estimates ofgroup size, according to guidelines presented in Smithand others (1994).

We observed 38–58 dolphins in 25 groups duringsurveys of the Jamuna River (sighting rate 5 0.13 sight-ings/km or 1.5 sightings/h; mean group size takenfrom best estimates 5 1.8, SD 5 1.4, range 5 1–7) and34–43 dolphins in nine groups during the surveys of theKushiyara River (sighting rate 5 0.08 sightings/km or0.6 sightings/h; mean group size taken from bestestimates 5 3.8, SD 5 2.8, range 5 1–8). In addition,during a short visit to the Burhiganga River near Dhaka,we observed two to three dolphins in a single group.

These data are clearly inadequate for estimatingdolphin abundance, but we are encouraged by thenumber of dolphins observed in the areas we visited. Itmay be significant that group sizes were larger in theKushiyara River, in comparison to the Jamuna River, butsightings were less frequent.

Habitat

The hydraulic constraints and clumped nature ofbiological productivity in lotic systems result in P.gangetica exhibiting a marked preference for areas ofriver with well-defined physiographic and hydrologicfeatures (Smith 1993, Reeves and Leatherwood 1994b).In the Karnali River, Nepal, Smith (1993) observeddolphins occurring most often in ‘‘primary habitats’’where convergent streams create an eddy countercur-rent system in the mainstream flow. Less often dolphins

were found in ‘‘marginal habitats’’ where a sharpupstream bend creates a similar eddy countercurrentsystem but of smaller dimensions.

Smith (1993) hypothesized that by maintaining posi-tion behind the velocity gradient of countercurrents,river dolphins take advantage of the high biologicalproductivity within countercurrents while monitoringforaging opportunities for fish swimming along migra-tory pathways of the mainstream flow. He furthersuggested that dolphins optimize energy outputs bymaintaining longitudinal position along the river coursewithout having to swim against swift downstream cur-rents.

We believe that eddy countercurrents, called duars inBengali (or koom or khari in larger rivers), are essentialto the survival of river dolphins and to the productivityof riverine biota. A recent fisheries study in the north-east region of Bangladesh supports the idea of a linkagebetween dolphin occurrence and duars (BWDB 1994).The same study also found that duars are essentialoverwintering habitat for boromaach (commercially im-portant fishes including major carp, catfish, and otherlarge migratory species).

During surveys in the Kushiyara River, all sightings ofdolphins were located within the eddy boundaries ofobvious duars. Larger duars, created by sharp meandersand convergent or divergent channels, contained agreater number of dolphins than smaller duars, createdby gentle meanders. River channels in the KushiyaraRiver are a few hundred meters wide and are generallycontained within well-defined banks. In contrast, riverchannels of the Jamuna River are generally severalkilometers wide and uncontained within defined banks.Duars in the Jamuna River tend to be much larger andless well defined. Consequently, sightings of dolphins inthe Jamuna River were generally located within duars,but the dolphins’ fidelity to these areas did not appearto be as great.

The concentration of dolphins in limited and circum-scribed areas makes them particularly vulnerable tohabitat disturbance from water development, directexploitation, accidental entanglement in fishing nets,and local sources of pollution. The aggregate nature ofriver dolphin distribution can also be used to thedolphins’ advantage by allowing conservation strategiesto focus on areas that already require judicious steward-ship for protecting vital fishery resources.

Water Development Planningand Impact Assessment

The environmental consequences of water develop-ment projects are often significant and far reaching, but


may become evident only over an extended period oftime. Although the absence of long-term studies, withadequate pre- and postdevelopment data, make it diffi-cult to conclusively predict the exact nature and magni-tude of potential effects, any development that reducesthe complexity of a river’s natural flow pattern is reasonfor concern (Reeves and Leatherwood 1994b).

The absence of conclusive evidence of deleteriousconsequences should not be taken to mean that thereare no consequences, but that our knowledge may beinadequate; hence, empirical studies are needed, anduntil adequate information is available, planners shouldevaluate impacts conservatively on the side of adverseeffects. Comprehensive planning should also considerthe cumulative impacts of multiple projects, as well assynergistic linkages between projects or with otherfactors that may threaten dolphin survival.

How Water Development AffectsRiver Dolphins

Embankments

Embankments contain the flow of water, sediments,and biota in a more confined and uniform channel. Byartificially raising riverbanks, these structures preventoverspill onto the adjacent floodplain. When high flowsrecede at the end of the monsoon season, sediments aredeposited in the riverbed instead of on the floodplain.Duars are often eliminated or reduced in size fromincreased sedimentation and decreased hydraulic com-plexity.

Embankments restrict access to floodplain habitat,which is critical for the reproduction and growth of60% of the total number of riverine fish species inBangladesh that are floodplain dependent (Boyce 1990).A study on the impact of embankments constructed inthe Megna River near Chandpur found that fish produc-tion declined by over 35% and several economicallyimportant species disappeared entirely two years afterconstruction (Ali 1990).

High Dams

Dam construction and operation cause major changesin the flow regime, sediment load, and water quality ofrunning waters. Dams choke off the dynamic attributesof downstream waters and quench the flow-through ofsediment essential to the formation of stream channelislands and bars (Ward 1975, Sioli 1986). Downstreamdischarge is prevented from reaching the critical magni-tude necessary for water to overspill riverbanks ontoadjacent floodplains, thereby resulting in dramatic

decreases in fish production. Natural fluctuations inflow, temperature, and detritus loading, which encom-pass optimum conditions for a large number of aquaticorganisms, are suppressed by dams, and the number ofecological niches available for supporting diverse com-munities of riverine biota is reduced.

Barrages

Barrages are gated dams built across rivers to regu-late water discharge. During monsoon season flows, thegates are generally left open and then progressivelylowered as the flood recedes to divert water into canalsfor irrigation and sometimes navigation purposes(Reeves and others 1991). Although downstream move-ment of dolphins through barrages can occur while thegates are open, high-velocity currents within the open-ings probably prevent upstream movement. The persis-tence of isolated upstream subpopulations could beprofoundly affected if only a few animals emigrateddownstream through the gates of a barrage (Reeves andothers 1991). Even if there is no loss of dolphins fromupstream subpopulations, the effects of subdividing asingle population into noninteracting insular unitsincreases their vulnerability to environmental, demo-graphic, genetic, and etiological threats. It may beinstructive to consider that dolphins no longer occur insufficient numbers to constitute viable populationsupstream of barrages in the Mahakali, Sapta Kosi, andNarayani rivers of Nepal (Smith and others 1994).

Barrages also block migratory routes of anadromousand catadromous fish species. A dramatic illustration ofthe impact of barrages on migratory fish is that aftercompletion of the Farakka Barrage, landings of thecommercially important anadromous fish, hilsa (Hilsailisha) were reduced by more than 99% upstream of thebarrage (Jhingran 1982). The ecology of rivers belowbarrages is also altered such that during the dry season,downstream flows are often reduced to only what seepsbelow the barrage. This results in significant reductionsin the amount of habitat available for dolphins and fish.

Closure Dams

Closure dams cut off the flow of a distributary thatmay be causing unwanted erosion. These dams elimi-nate downstream habitat in the distributary channeland generally result in duars located at the old channeldivergence of the mainstream filling in with sediments.Closure dams have failed at the Fulchari distributary ofthe Jamuna River and Dewanganj anabranch of the OldBrahmaputra River. The environmental consequencesof the construction of these dams and their subsequentfailure are unknown (FAP 21/22 1993).


Groins and Spur Dikes

Groins and spur dikes are transverse-flow diversionstructures projecting from the riverbank out into thechannel. If designed properly, these structures provideindirect flood protection by deflecting the erosive forceof water currents away from the riverbank. Thesestructures are effective at protecting the banks of smalland medium-size rivers but have not always provedsuccessful at protecting the banks of large braided riverssuch as the Jamuna (FAP 21/22 1993).

Groins and spur dikes constructed to close olddistributary channels have inadvertently created artifi-cial duars as a result of the scouring action of thedeflected flow. A spur dike on a distributary channel ofthe Kushiyara River induced a 32-m-deep scour hole inthe middle of the channel, where previous water depthwas only around 9 m (BWDB 1994). During surveys ofthe Kushiyara River we observed six to eight dolphinssurfacing in this duar, including two small calves.

Withdrawal of Surface Water

Dry season withdrawal of surface water reduceshabitat available for dolphins and fish. Overwinteringfish broodstocks become increasingly vulnerable tooverfishing and natural mortality as water supply isreduced. The effects are particularly magnified whensurface water is pumped from a river where water hasalready been diverted by upstream barrages, such as isthe situation in the Padma River, where the Ganges-Kobadak Irrigation Project (GKIP) pumps water fromriver flow that has already been reduced by the FarakkaBarrage.

Dredging and Loop Cutting

Some stretches of rivers in Bangladesh have beendredged to benefit navigation and reduce flooding.Smaller rivers are sometimes straightened by eliminat-ing meanders and loops. Loops are cut by gouging ashallow canal across the base of the loop and allowingthe monsoon flood to excavate the bypass channel(BWDB 1994). This practice results in the deposition oflarge amounts of sediment and the elimination of duarsdownstream of the cut. In the Kushiyara River, loopcutting has caused major duars to fill in with sedimentsand previous highly productive fisheries have beenseverely damaged (BWDB 1994).

Summary of Water Development ProjectsAffecting River Dolphins in Bangladesh

Water development projects in Bangladesh are largelyfocused on flood protection and irrigation. Most of the

country is unsuitable for large dams or barrages be-cause of the relatively flat geography and the migratorybehavior of river channels. A notable exception is theKaptai Dam in the Karnaphuli river located in the farsouth of the country.

We identified 11 water development projects (al-ready constructed, planned, or currently in construc-tion) that may have significant effects on river dolphinsand other aquatic biota in Bangladesh (Table 1). Theseprojects include two high dams, one closure dam, fivelevee and groin projects, and two dredging or loop-cutting projects. Two of these projects, the FarakkaBarrage and Tipaimukh High Dam, are located in Indiabut are included because of their realized or potentialeffects on downstream habitat in Bangladesh.

Threats from Other Human Activities

Use of Dolphin Products

Dolphin oil is used by people in Bangladesh as aliniment, claimed to be effective for treating rheuma-tism, burns, and nervous disorders, and a tonic fortreating impotence and asthma (Haque 1978, 1982,Pelletier and Pelletier 1980). During this study, we weretold that pregnant women sometimes drink the oil inthe belief that it will ensure a healthy baby and that theoil is mixed with banana leaves and fed to cows to fattenthem before being taken to market. Pelletier andPelletier (1980) described a factory in Chandpur usedfor processing dolphin oil. We have no information onthe status of this operation.

In the town of Benibazaar, near the Kushiyara River,we interviewed villagers who told us that local fisher-men never hunt the dolphins, but when they becomeaccidentally entangled in their fishing nets, they kill theanimals, if they are not dead already, and bring thecarcass to the market. The meat is popular among somepeople, especially the ‘‘uneducated’’ and minority Hinducommunity, selling for 160 taka (US $4; 40 taka 5 US$1) per kilogram. We were told repeatedly that peoplewithin the majority Muslim community do not eatdolphin meat, although a few villagers reported know-ing others who had ‘‘tasted’’ it, but that Muslims will buyportions of the carcass to render for oil. A fishermanreported that one large dolphin supplies 8–9 kg of oil.In the neighboring town of Zokiganj, fishermen told usthat dolphins weighing 25–35 kg and 40–50 kg sell for500–700 taka and 1000–1200 taka, respectively. Theyalso told us that when dolphins are accidentally caughtin fishing nets, they frequently divide the carcass anddistribute the pieces among neighbors.

Dolphin meat, entrails, and oil are also used as anattractor for the schilbeid fish Clupisoma garua. While


drifting downstream, fishermen in small sail/row boatstrail bound pieces of dolphin body parts off the side oftheir vessel while sprinkling the water with a mixture ofoil and minced dolphin flesh (Figure 3). Small un-baited hooks are then used to catch the fish when theyrise to the surface within the oil slick. We observed thisfishing technique being used in the Burhiganga andMegna rivers near Dhaka and in the Jamuna River nearSirajganj.

We were told in the town of Sirajganj that there are30–40 boats using this fishing technique and that eachboat requires three to four dolphins per year. Fisher-men using this technique buy dolphin carcasses at a costof 600–3000 taka each from other fishermen who catchthe animals accidentally (?) in monofiliment gillnets,depending upon size and availability. This means thatfishermen in Sirajganj support an annual take of 90–160 dolphins worth 54,000–480,000 taka. The cumula-tive impacts of high mortality from exploitation (fisher-ies bycatch and directed hunting) and waterdevelopment projects could undermine the viability ofdolphins in the Jamuna River.

Fisheries Bycatch

Cetaceans worldwide are threatened from incidentalmortality in gillnets (see IWC 1994, Reeves and Leather-wood 1994a). According to local fishermen, incidentalcatch in monofiliment gill nets, called current jals, istheir primary source of dolphin products. It is difficultto determine if the catch of dolphins in nets is deliber-ate or accidental, especially since dolphin products arehighly valued and nets are often deployed for multispe-cies catch (Reeves and others 1993).

Although current jals with a stretched mesh size ofbelow 4.5 cm are prohibited in Bangladesh, their use isincreasing throughout the country (Liquat Ali personalcommunication). We observed these nets being usedextensively in the Kushiyara, Burhiganga, Megna, andJamuna rivers, and fishermen generally appeared to beunaware of regulations prohibiting their use. Currentjals are sold openly and are widely available in localmarkets; over 1000 nets were reported displayed at JawalBazaar, located near the Surma River (BWDB 1994). Wewere told by fishermen in the Kushiyara River thatdolphins are sometimes caught in jam jals. Theserectangular nets have an 8- to 10-cm mesh size and areused to catch boromaach broodstock in river duars(BWDB 1994).

Directed Catch

Local villagers appeared to be unaware that huntingdolphins is prohibited under the laws of Bangladesh

(Wildlife Protection Act 1974). Although the people weinterviewed claimed that they never personally huntdolphins, they regarded the hunting activities of othersas a legitimate use of a resource that was of no benefit tothem. In villages along the Kalni-Kushiyara river, wewere told that a small group of fishermen from a Hinduminority caste in the Bhawol Thana (Sylhet District)come every year during December or January to huntdolphins in major duars. They hunt dolphins at nightwith long iron-tipped harpoons made from bamboo.

Overexploitation of Fisheries

The rivers of Bangladesh sustain one of the mostproductive freshwater fisheries in the world (Liquat Alipersonal communication). Significant declines in carpand catfish production suggest that exploitation may beexceeding sustainable yields (BWDB 1994). Major fac-tors cited for declines are the use of small mesh gillnets(current jals and kona ber jals) in tributaries and harvest-ing boromaach in duars during their breeding season.The strong correlation between the distribution of riverdolphins and boromaach species and the reported de-cline of these fishes may indicate a potential problem inmaintaining an adequate food base to support dol-phins.

Pollution

The main sources of water pollution in Bangladeshare leather, paper and pulp, fertilizer, pharmaceutical,sugar, jute, textile, and petrochemical industries, whichgenerally discharge untreated wastes directly into rivers(Dalal-Clayton 1990). The widespread use of fertilizersand pesticides for ‘‘green revolution’’ rice crops alsocreates serious water-quality problems. Proposed em-bankment and compartment projects are expected tolead to increased dry season irrigation. Farmers whoirrigate their crops use twice as much fertilizer andpesticides as those who depend upon rainwater (Bangla-desh Agricultural and Development Corporation 1989).

Recent studies of the biodegradation capacity andresidue patterns of organochlorines in dolphins inhab-iting the Ganges river in India indicate that, similar tomarine cetaceans, P. gangetica is unable to metabolizethese chemicals (Kannan and others 1994). The highconcentrations of heavy metals (Fe, Mn, Zn, Cu, Pb, Mi,and Cd) found in the tissues of one neonatal maledolphin and one slightly larger immature male dolphin(Kannan and others 1993) suggest considerable trans-fer of these contaminants across the fetal membraneand through milk (Reeves and others 1993). The lack ofsystematic monitoring of pollutant levels in Bangladesh


Table 1. Water development projects affecting river dolphins in Bangladesh

Name of project LocationDescription of project

and general effects StatusSummary of

dolphin occurrence

Bank Protectionand RiverTraining PilotProjects (FAP21/22)

Right bank ofJamuna Rivernear Kamarjaniand left bank ofJamuna RivernearBahadurabad

These projects are test structures forinvestigating if river training isfeasible. Three groins have beenconstructed in Kamarjani andeight slope embankments, with atotal length of 800 m, are plannedto be built near Bahadurabad.Feasibility report states that thestructures will have only localeffects and that since ‘‘there areno natural areas left to protect, noadditional environmentalassessments are needed’’ (FPCO1995).

Construction ofgroinscompleted in1996;embankmentscurrently inconstruction

Dolphins observed nearBahadurabad duringsurveys in April 1996 (seesection: Status andDistribution). No surveyshave been conducted inthe Jamuna river nearKamarjani.

BrahmaputraRiver BankPriority Works(BPW)

Jamuna River nearSerajgonj,Rajshahi

The aim of the BPW is to protectcritical sections of the river bankby linking remaining sections ofthe Brahmaputra RightEmbankment (BRE) with two hardpoints (short embankments usedto divert flow) and low earthernembankments know as cross bars(BWDB 1992). Although fisheriesin the Jamuna River have declinedby more than 50% since 1983, aloss largely attributed to the effectsof BRE, the environmentalassessment for the BPW does notaddress potential new impacts(BWDB 1992).

Project currently inconstruction

Dolphins observed in thearea during surveys inApril 1996 (see section:Status and Distribution).

DhaleswariClosure Dam(part of theJamunaMultipurposeBridge Project)

Dhaleswari River atthe divergenceof the JamunaRiver nearSerajgonj

The Dhaleswari closure dam wasconstructed to protect thefoundation of the Jamuna Bridgefrom erosive floods. The dam willreduce overall flow in the river by21% and by as much as 53% in thePungli, Louhajang, and Elongjanidistributaries. Pollutant loads areexpected to increase in theBurhiganga and Turag riversbecause of reduced dilution fromthese tributaries (JMBA 1994).

Year of completion1996

We have no information onthe occurrence ofdolphins in the Dhaleswaririver or the Pungli,Louhajang, and Elongjanidistributaries. We haveobserved dolphins in theTurag and Burhigangarivers during casual visits.

Farakka Barrage Ganges Rivermainstem neartheIndia/Bangladeshborder

The Farakka Barrage was built todivert water from the Ganges tobenefit navigation in the HooghlyRiver. Although the magnitudeand extent of impacts arecontroversial (see Crow and others1995), the barrage has fragmentedthe metapopulation of riverdolphins at the center of theirdistribution, caused salineencroachment into delta habitat,blocked spawning migrations offish and prawn species, andreduced downstream aquatichabitat during the dry season(Reeves and others 1993).


No surveys have beencompleted in the PadmaRiver downstream of thebarrage. During the dryseason, the river coursebecomes shallow enoughto cross on foot, with onlyscattered pools containingsufficient water to supportdolphins. If dolphinsbecome trapped in theseareas, they would be atincreased risk of starvationfrom lack of prey,accidental entanglementin fishing nets, anddirected hunting.


Table 1. (Continued)


and general effects StatusSummary of

dolphin occurrence

Jamalpur PriorityProject (FAP3.1)

Divergence ofJamuna and OldBrahmaputrarivers nearJamalpur

This project proposes to construct an82-km embankment along leftbank of the Jamuna River and a43-km embankment along theright bank of the OldBrahmaputra River for floodcontrol purposes (FPCO 1995).Studies are planned to considerenvironmental issues but it isunclear how these studies couldaffect engineering designs alreadyin progress.

Detailedengineeringstudy currentlyin progress


Jamuna BridgeProjectEmbankments

Jamuna Riverupstream ofSerajgonj,Rajshahi

Embankments are being constructedto protect the bridge foundationfrom erosive floods. Structuresconsist of paired embankmentsupstream of the bridge and a hardpoint below the bridge. Theembankment on the left bank willbe linked to the BPW.

Construction inprogress


Kalni-KushiyaraRiverImprovementProject

Kushiyara RiverbetweenAsmiriganj andKatkhal,Chittagong

The aim of this project is to facilitatepassage of water in the KushiyaraRiver by constructing hard pointsand dredging shallow bar areas(Henry Werszko, personalcommunication). Three sites willbe dredged for 0.25–1.0 km ofriver length each. If successful, 10additional sites will be dredged inthe 50 km stretch of river betweenMarkuli and Mudha (RaguibUddin Ahmed, personalcommunication).

Advanced stages ofplanning

Dolphins observed in thearea during surveys inOctober 1995. If theproject works asenvisioned it couldenhance dolphin habitatby inducing the formationof duars. A potentialproblem is the greatincrease in turbiditycaused by the dredgingoperations (Raguib UddinAhmed, personalcommunication).

Kaptai Dam Karnaphuli Riverat Kaptai,Chittagong

The Kaptai Dam is the only high damin Bangladesh and contains thelargest man-made freshwaterreservoir in the country. The damwas constructed for hydropower,flood control, and irrigationpurposes. No long-termmonitoring has been done toinvestigate the impacts of the dam.


With the exception of asingle dead dolphin foundfloating in the KaptaiReservoir (Reeves andLeatherwood 1995) and areport of a sighting of twodolphins in 1991 (Reevesand others 1993), we haveno information on theoccurrence of dolphinsabove the dam. Dolphinsare reported to still occurin the Karnaphuli Riverbelow the dam (Reevesand others 1993).

Manu Barrage Manu River nearManu,Chittagong

The Manu Barrage was constructedfor irrigation purposes and divertswater from the Manu River intothe embanked Kawadigi Haor. Thegates of the barrage are openedduring the monsoon season.


Dolphins have been extirpatedfrom the Manu River, aboveand below the barrage,during the dry season. Wehave no information on theoccurrence of dolphinsduring the monsoon season.

Teesta Barrage Teesta River nearRangpur

The Teesta Barrage was constructedfor irrigation and flood controlpurposes. We have no otherinformation on the barrage.


We have no information onthe historical or currentoccurrence of dolphinsabove or below thebarrage.


(Dalal-Clayton 1990) does not allow for a credibleassessment of the problem.

An Action Plan for Conserving River Dolphinsin Bangladesh

We recognize that issues related to the welfare of arapidly growing and economically impoverished humanpopulation will take precedence over concern for pre-serving dolphins. The authors of the present paper alsobelieve that the ecological health of rivers will continueto play a vital role in supporting the large majority ofpeople in Bangladesh and that the issue of dolphinpreservation reflects the greater conservation concernsof this environment.

There is a need for conservation action to preserveriver dolphins in Bangladesh, not because the species isin immediate danger of extinction, but because thereare still a sufficient number of animals for early conser-vation intervention to be effective in the face of presentthreats. Discouraging results of efforts to preserve

another platanistoid dolphin, the baiji (Lipotes vexillifer),in the Yangtze River of China, suggest the futility ofeleventh hour conservation efforts, occurring only afterpopulations have reached a certain threshold of decline(see Leatherwood and Reeves 1994).

To conserve dolphins in Bangladesh we recommendthat:

1. Dolphin monitoring should be an integral compo-nent of environmental impact assessments of majorwater development projects of Bangladesh. Credibleassessments of the impacts of water developments ondolphins require standardized surveys to be conductedbefore and after construction of a project. Technicalexpertise for monitoring programs is available throughthe IUCN Species Survival Commission Cetacean Spe-cialist Group and the Asian River Dolphin Committee.

2. Structures should be designed and incorporatedin barrages, dams, and regulators to facilitate upstream,downstream, and lateral migrations of fish and prawnspecies. Designs for fish bypass structures should beevaluated according to the ecological circumstances of

Figure 3. Fishermen using dolphin oiland body parts as an attractant for thefish species C. gaura.

Table 1. (Continued)


and general effects StatusSummary of dolphin

occurrence

Tipaimukh HighDam

Surma River,Cachar, India

This high dam is being constructed forhydroelectric purposes. It may alsohave flood control and irrigationbenefits but we no information ontechnical specifications.

Currently inadvanced stagesof planning

Dolphins observeddownstream in theKalni-Kushiyaradistributary during surveysin October 1995. Theabsence of informationabout this dam does notallow for an assessment ofpotential effects ondolphins.


the environment where the project is located. Adher-ence to water management guidelines, which considerthe seasonal migration patterns of target species, andpostconstruction monitoring will be critical for success-ful operation.

3. Aquatic biodiversity sanctuaries should be estab-lished in the deeper and most important duars. Fishsanctuaries in duars are generally supported by localfishermen and have been shown to be successful inprotecting fish broodstock where they have been effec-tively implemented; often they do not work because ofineffective enforcement (BWDB 1994). We recommendincluding dolphins (and other aquatic species) as anintegral part of fish sanctuaries. A high abundance ofdolphins indicates high abundance of boromaach species(BWDB 1994), thereby reflecting the efficacy of thesanctuary system. Involving local fishermen in surveil-lance and enforcement will be critical for successfulsanctuary management. The installment of passive net-and line-fouling devices should be considered to discour-age poaching and protect dolphins from accidentalentanglement in fishing nets. These structures mayhave added benefits of enhancing habitat by increasinghydraulic complexity and scouring (BWDB 1994).

4. The creation of artificial duars should be consid-ered to mitigate for dolphin habitat degraded by waterdevelopments and to improve overwintering groundsfor boromaach broodstock. Artificial duars have beeninduced by the construction of spur dikes and bottomsills (BWDB 1994). Other options for inducing orenhancing duars include constructing hard points atchannel meanders or groins oriented perpendicular tothe streambank or in an upstream direction. As with allengineering options, construction should be ap-proached with caution and preconstruction modelingand postconstruction monitoring should be key compo-nents of environmental enhancement plans.

5. Regulations prohibiting the use, sale, transport,and manufacture of current jals and kona ber jals shouldbe strictly enforced. Effective enforcement will requireshutting down marketing centers and eliminating smug-gling (BWDB 1994).

6. Efforts should be made to develop, make avail-able, and promote substitutes for dolphin oil used bylocal people to attract fish and for medicinal purposes.Crude shark and sardine oil has been shown to beeffective at attracting fish (Reeves and Leatherwood1995). We recommend that adequate supplies be madeavailable to fishermen. Considering the high expense ofpurchasing dolphin carcasses, this initiative may beefficiently accomplished as a for-profit venture con-ducted by local businessman.

7. Conservation of dolphins should be promoted

through a public awareness program. The local mediashould be used to publicize local myths and religiousbeliefs regarding the protected status of dolphins.Successful programs of this type have contributed toconservation efforts of the species in India.

8. A net compensation/dolphin release programshould be established to compensate fishermen fordamages caused by cutting nets (other than current jalsand jam jals, which are illegal) to release entangleddolphins alive. This initiative should follow-up publicawareness programs. A successful program of this typehas reduced mortality of Irrawaddy dolphins (Orcaellabrevirostris) in the Mekong river system in Laos (Bairdand Mounsouphom 1994, Baird and others 1994).

9. Nonstructural strategies should be promoted toreduce human and economic losses associated withhigh floods. Emphasis should be on flood adaptation,rather than flood prevention (Haque 1994). Nonstruc-tural measures include, among others, flood forecast-ing, early warning systems, flood insurance, and floodrelief and rehabilitation (Haque 1994). These measuresmay be more effective at mitigating destructive effectswithout causing deleterious impacts.

Acknowledgments

Field research was funded by the Whale and DolphinConservation Society and the Chicago Zoological Soci-ety. We wish to thank M. Mozammel Hossain, M. AnwarHossain, and Siraj Uddin Ahmed Sento for their assis-tance with the surveys. Randall Reeves, James Boyce,and two anonymous reviewers provided helpful reviewsof the manuscript.

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