Research articles NAT. NAT. HlST. BULL. SIAM S配 .42: 15 9- 175 ， 1994

IRRAWADDY DOLPHINS (ORCAELLA BREVIROSTRIS) IN SOUTHERN LAO PDR AND NORTHEASTERN CAMBODIA

Ian Ian G. Baird 申 and Bounhong Mounsouphom**

ABSτ 'RA CT

百 e presence of 血巴 Irrawaddy dolphin Orcaella brevirost 巾 in the ，Sekong ，Sesou ，

Sekhaman ，Sen 釘 nnoi ，Sekampoh ， and Sepi 組 Rivers in Southern La o PDR ，and the Mekong Ri ver in in North ・eastern Cambodia ，was documented between December 1991 and March 1994. Inf or-

mation mation on dolphin feeding and se 部 onal migratory behaviour has been collec 旬d. An cedotal re-

ports 針。 m villagers imply that populations have gr 官atly declined in recent years. Many villagers in Sou 血ern Laos and Cambodia believe dolphins are reincarnated humans ， and the species is highly

respected respected by local people ，who never eat 白e meat of dolphins and only very rar 官ly harm them 泊.tentionally. Nevertheless ，several sources of an 曲ropogenic mortality have b民 n identified. 百1凶巴 include include being killed in gillnets ， by explosives used for fishing by Cambodians in portions of of the Mekong and Sekong Ri vers sh 眠 d between Laos and Cambodia ， and being shot by soldiers

or or villagers unfar 凶H 紅 wi 血血em.M 組 y were probably killed during United States aerial bombing raids raids over 白e Sekong Ri ver during 血e In dochinese War. Dec reases in fish catches also indicate a reduction reduction in available p隠 y. Lar ge-scale dams proposed for the Mekong and Sekong 悶 vers threaten the the species in La os and Cambodia ， as well 踊 m 飢 y species of migratory fish. A comrnu 凶ty-bωed

research research project h錨 been set up in Southern Laos to investiga 低回ditional fisheries ，fish and dol- phin phin ecology and biology ， and other environment and socio-economic issues of signific 釦 ceto 血e fishing fishing villages where work is continuing.

町 TRODUC 官 ON

Irr awaddy dolphins Orcaella brevirostris ，which reach about 2.5 m 泊 leng 血， are dis- 凶buted 企om 血.e Bay of Bengal east to New Guinea ，and 仕om northern Australia thiough 血e South China Sea (LEA' 官 ffiRWOOD ET AL. ， 1984; MARSH ET AL. ， 1989). A brief review has been given in BAIRD ET A L. (1 994). 百lere have been numerous sightings ，but no systematic

S町 veys for 血is sp 民 ies have been conducted. Included in the habitat of 出is cetace 佃紅ethe large river systems of the Irr awaddy ，Mah ak: am ，姐 d Mekong. In Kal imantan ，In donesia ，

白ey 紅 'e found in lak: es at least 200 km up the Mah ak: am Ri ver (TAS' AN ET AL. ， 1980; T AS' AN &L 臥 THERWOOD ，1984). 百 is species has been seen almost 1300 km up 血e Irr awaddy

Ri ver in Burma ，but app 紅 'ently does not occ 町 in 血e Salween and Sittang ，the other large rivers 泊也e ∞四位y(UTINT 田町， 1977). In Th ailand ，the species w 槌 previously known to enter 1釘 ge rivers ，including the Chao Phraya (LEKAGUL & MCNEELY ， 1977) and the

'" '" Ear血 Island Ins titute (Th ailand and In dochina) ，Box 19 ，Huamak Post Office ，Bangkok ，百泊 land 10243 柿La o Comrnunity Fisheries and Dolphin Pro tection Pro jec t， National Office for Natural Resources Conserva- tion tion and Watershed Management ，De partment of Forestry ，Vientiane ，Lao PDR

159 159 160 160 IAN G. BAIRD AND BOUNHONG MOUNSOUPHOM

Chanthaburi Chanthaburi River ， as reported by Chanthaburi residents living a1 0ng the river. It is possible that that pollution and heavy river traffic on 出e Chao Phraya Ri ver and dams on 白e Chanthaburi Ri ver have resulted in the dolphins' disappearance from these rivers in recent years. Irr awaddy dolphins dolphins are also found in brackish estuaries and salt-water coastal waters in many Asian countries ，including Thailand ，where 出ey 紅 e often refe 町'ed to as “ pla loma hooa baht" be- cause cause their snouts 訂 e rounded like a monk's bowl (“ hooa b油 t"). In In Indochina ，LLOZE (1 973) documented the presence of Irrawaddy dolphins in the Vietnamese Vietnamese and Cambodian portions of the Mekong Ri ve r. Recent summaries of dolphins (KLINOWSKA ， 1991; MARSH ET A L.， 1989) do not include Lao PDR in the known distribution of of the species. CHAZEE (1990) reported on a river mamm a1 present in Southem Lao PDR ， downstream of the Mekong's Khone Waterfalls ，and a1 so in the Sekong and its 佐ibutaries ， the the Sekhaman and Senamno i. Th ev il1 agers ca1 1ed the anim a1 “pa kha" ，which is the loc a1 Lao Loom word for dolphin. CHAZEE (1990) reported 白at the is not intentionally hunted ， but is occasion a1 1y caught accidentally in nets used for fishing ， sometimes resulting in in mortality. He suggested that the animal was m 訂 ine in origin ， but concluded ， based on certain certain characteristics that he did not elaborate on ，白紙 it was a sirenian ， not a cetacean. This observation observation was incorrect ，and the mistake in identification ma 可yh加av 刊e been based on infor- mation mation Cαhazee collected 陀rl 'ega 紅rding the Lao 'τn 百leung e白凶c group's belief 白tha 幻t gra 酪ss ，儲ass討ir 閃e叩凶lI n 佃ansd 伽o. In April 1992 ，Lao Theung people in Sekong Province reported hav- ing ing previously observed dolphins feeding on submerged vegetation near the edges of rivers. τbe dolphins were probably feeding on sm a1 1 cyprinid fishes that sometimes stay amongst submerged vegetation. The mistaken identification may also have occured because the head and body of the Irrawaddy dolphin resembles 白紙 of a sirenian. The species does not have a pointed pointed snout typical of many other species of dolphins.

In In this paper we report on observations made during our prelimin 訂 y surveys of por- tions tions of the Mekong and Sekong Ri vers in southem Lao PDR 佃 d northeastem Cambodia ， emphasizing emphasizing verbal reports and perceptions of loc a1 people about dolphins ，組 d frrst hand observations observations of dolphin distribution ， food habits and mo rta1 ity. A brief summary of 0町 survey survey has been given by BAIRD ET AL. (1994); the present account provides many more details. details.

METHODS

Surveys Surveys were conducted during December 7-15 ，1991 ，and March 27-April lO， 1992 ， in in the southem Lao provinces of Sekong ，Attapeu ， and Champasak. Loc a1 Lao Loom and Lao Theung people in 34 villages siωated along the Sekong Ri ver between Sekong and 血e Lao/Cambodian border in southem Attapeu Province were systematic a1 1y interviewed dur- ing ing August 1992. Work was done in Champasak Pr ovince between January 1993 and March 1994 ，and in Sekong and Attapeu Provinces during August 5ー15 ，1993.τbe Mekong Ri ver in in North-eastem Cambodia was surveyed in March 1993. In all cases ， except in Cambodia ， rivers rivers were travelled by boat and observations of dolphins ，fish and their relationships to IRRA WADY DOLPH 別 S (ORCAELIA BREVIROSTRIS) 町 SOU 百iERN LAO PDR 161

loc a1 people were recorded. During 白e survey done in Cambodia ，boats ，trucks ，and a heli 旬 copter copter were used to 位avel a1 0ng the Mekong Ri ver north from Phnom Penh to. the Lao and

Cambodia border ，passing the provinces ofKampong Ch 創 n，Kr atie 組 dSωng Treng. lt took one one week to complete the round- 凶p joumey. Discussions with vi1l agers living a1 0ng river shores shores were used to collect information on bo 白 historic a1 observations and the current pres- ence ence of dolphins and various fish species. lnstances of dolphin mo rta1 ity in Southem Laos have have been recorded since Decembero 1991 ， based on observations and credible reports 企om loc a1 people and govemment offici a1 s. Full necropsies were performed on 血ree dead animals in in 1993. Skin ，blubber ，mus c1 e， and liver samples were collected for genetic analysis from

血ree dead anim a1 s in 1993 and blubber and skin s卸 nples were collected from 血ree other anim a1 s in 1992. Between January 1993 and March 1994 ， the dolphin population in 由e

po 凶 on of the Mekong Ri ver bordering Laos and Cambodia ne 紅 the Lao vi1l ages of Hang

Sadam 佃 dH 組 g Kh onew 酪 estimated based on numerous daily observations by the authors. In In Apri11993 ， each of the 120 Lao families living in the vi1l ages of Hang Sadam and Hang Kh one were systematic a1 1y and individually interviewed by the authors and other staff members of 山 Lao Community Fisheries and Dolphin Protection Projec t. Inf ormation on

thefi 田ding habits and se 錨 onal migrations of the dolphins has a1 so been collected through vi1l ager interviews ，observations of dolphins in the field ，and inspection of remains of dol- phin phin prey collected a1 0ng the Lao/Cambodia border in Southem Champasak Pr ovince ，Lao PD R.

RESUL TS AND DISCUSSION

Distribution Distribution of Dolphins in Lao PDR and Northeastern Cambodia

Irr awaddy dolphins were sighted by the authors in the Mekong Ri ver ， but not the Sekong ，Sekham 姐， Senamnoi ，Sesou ， Sepian or Sekampoh Ri vers. However ，v i1l agers re- lated lated numerous accounts of dolphins in the Sekong and its larger 凶butaries in southem Laos. In In addition ，a skull of a dead dolphin was recovered near Sekong town ，which is next to the Sekong Ri ver ， in December 1991 ， and a photograph of a dead dolphin found in the Sesou Ri ver taken in 1984 was obtained from the Lao govemment.

Sightings Sightings during the surveys and reports from vi1l agers indicate that there 釘 'etwomain areas areas in Lao PDR inhabited by Irr awaddy dolphins. The frrst is 泊 the southem-most section of of the Mekong Ri ver 泊 Champasak Province ，a1 0ng the Cambodian border.τ 'h e other is in

the the Sekong Ri ver ，itself a 住ibut 紅 y of the Mekong ， and some of its larger tributaries 泊血e provinces provinces of Sekong and Attapeu. Many ， if not a1 1，of 血e dolph 泊s pre 田 nt in Lao PDR probably probably spend at least some of the their time in Cambodia. Loc a1 s report that for the last few years dolphins have been observed only in 由e Sekong Ri ver in Lao PDR during 出e high-water high-water monsoon season ， before travelling down the Sekong Ri ver to Cambodia when

water water levels begin to go down. In the Mekong Ri ver ofLao PDR ， the dolphins 紅 eonlyfound a1 0ng a portion of the river bordering Cambodia. 162 162 IAN G. BAIRD AND BOUNHONG MOUNSOUPHOM

Th e great Kh one rapids and waterfalls are just north of the villages of Hang Kh one and H 叩 .g Sadam ，which are situated on islands in the Mekong Ri ver just across from Cambodia at at the southem-most point of Lao PDR.τ 'h eyappe 紅 to act as a natural barrier for the dol- phins ，and dolphins 紅 'e not believed to inhabit the Mekong Ri ver above the waterfalls. How- ever ，a number of locals from Don Dtan Village just north of the rapids and waterfalls re- ported ported having once s田 na group of dolphins 田町their village in 也e 1960s d町泊g 出e high- water water season. Th e dolphins were observed daily by the villagers for about one month before apparently apparently retuming south to the Hang Kh one lH ang Sad 倒 n 釘 ea.τ 'h e dolphins probably 佐avelled up “Hoo Sahong" channel ，which is one of the few Mekong Ri ver channels in the falls falls area that migrating fish c組 easilyascend. Irr awaddy dolphins ，which 紅 'e apparently the only only species of cetacean found in Lao PDR and Northeastem Cambodia ， are not known by villagers villagers living north of Don Dtan Village. In In the Sekong Ri ver ，which flows through the Lao provinces of Sekong and Attapeu before before entering the Mekong Ri ver in the North-eastem Cambodian province of Stung Treng ，

Irra waddy dolphins were 飽 portedly once very common wi 白ina200 ・km section of the Sekong Ri ver 合'om at least 60 km nor 血of Sekong town to the Cambodian border in Southem Attapeu

Pr ovince.τ 'h ey were also common in the Sekong Ri ver' s larger 凶 but 釘 ies in Attapeu Pr ovince ，including the Sekhaman ，Senamnoi ，Sesou ， Sepian and Sekampoh Ri vers. In In August 1992 ，villagers in 34 Lao villages situated along the Sekong Ri ver 企om

Sekong south to 血e Lao/Cambodian border were interviewed reg 釘 ding dolphins and 血e socio-economic socio-economic situation in the villages. Virtually all adults were farniliar with the dolphins.

Whi le the dolphins apparently used to be seen all ye 訂 round in many p制 s of the Sekong

Ri ver in Laos ，they 紅 'e now only seen 泊 s，omeye 紅 s，and mainly during 也emonsoonse 部 on (June (June to November) when the river rises. In In Cambodia ，interviews with villagers ，Fisheries Department officials ， boat owners ， 組 d UNTAC (United Nations Transitional Au 白ority in Cambodia) river patrol personnel ， indicated 由at the largest concentration of dolphins in the Mekong Ri ver in Cambodia exists in 白e provinces of Kr atie and Stung Treng ，which 訂 'e also two of the most remote and least populated populated provinces. Al though more people live in Kr atie ， only 60 ，000 people live in 也e whole of Stung Treng Pr ovince. Dolph 泊S 紅 'e also occasionally seen in the Tonlesap Ri ver (KL 町 OWSKA ，1991) ，and one animal w 部 observed and filmed in 血e Pasak Ri ver in 1993 (SANITHON H 凹 'AKOM ，pers. comm. ， 1993). Although no dolphins were seen during the Cambodian survey ，most villagers interviewed knew of them and said 由ey are at least oc- casionally casionally found in most parts of the Mekong Ri ver north of Phnum Penh. However ，most people people south of Kr atie said dolphins 釘 e only rarely seen ，and 白en mainly 泊血e monsoon season. season. Villagers identified five d田 p water pool are 剖 in an approximately 200-km section of 白e Mekong Ri ver between Kr atie and the Sωng Tren gIL ao border where dolphins 紅 e said said to live in considerable numbers on a regul 紅 basis. In order of impo 託ance as dolphin habitat habitat in terms of numbers of dolphins normally seen by villagers ，these pools are at Kh oopee ， Goi Hep ，Hang Kh one (La o/Cambodian border) ，Siem Bok ，and Gawtawmpbawng island.

百lese deep water pools 釘 'e apparently the prefer 官官 d habitat of the dolphins ，especially in 血e low-water low-water dry se 邸 on between December and May. Lao and Cambodian villagers have also IRRAWADY DOLPHINS (ORCAELLA BREVIROST Rl S) 町 SOUτ 'HE RN LAO PDR 163

reported reported that dolphins inhabit the Cambodian p紅 tof 血e Sekong Ri ver and 血e Sesan Ri ver in Cambodia.

Local ofPerceptions Dolphins

Villagers Villagers in Cambodia and Lao PDR believe 白紙 dolphins 紅 'e friends of humans. Al- though though not observed by the numerous villagers interviewed in Champasak ，Sekong or Attapeu Pr ovinces ，most people believe dolphins have saved people from harm when boats have been overturned overturned or people have been attacked by crocodiles.

M 組 y Lao people who have heard of dolphins but never seen them believe that they have breasts and vaginas like human women. Although dolphins do have mammary glands ， 血ey 紅 e small and si 伽 ated on the lower body ，which does not fit with the image Lao people have of large breasts on 白e upper half of the body ，like humans. Lo cals are also have a 国制onal fable in which dolphins and river tems are said ω have been reincama 飽d from humans who died after falling down one 由e great waterfalls called called Sompamit or Le e Pee. Ri ver tems 紅 'e often seen diving for fish near dolphins during the the dry season ，and some villagers believe dolphins chase fish to the surface so that the fish eating eating birds can eas i1 y catch them. Unlike Unlike ethnic Cambodians and Laotians ，who have never been known to eat dolphin meat ， the Cham Muslims who live along the Mekong Ri ver in Cambodia and Viet Nam sometimes sometimes hunt and eat dolphins. Th is was conftrmed 出rough numerous interviews with Cambodian and Vietnamese Chams as well as villagers along the Lao/Cambodian border.

Al l Laotians think highly of dolphins ，and villagers don't want to see them disappe 釘. However ，白 ey believe 血ey are rapidly nearing extinction. Th ere is v註加 ally no 住ade in dolphins in Lao PDR or northeastem Cambodia. How- ever ，a fish 回 der reported 白at in 1992 he bought a dolphin 企om local Lao fishers at Hang Sadam V i11 age. 百le dolphin died after being acciden ta1 1y en 旬ngled 加 ag i11 ne t. He p脱出e 白血nal on ice and transported it from the Lao/Cambodian border vi11 age of Wem Kh am to 血eLaon ・'h ai border. 百lai fish buyers refused to buy ，it and 白e animal was disc 紅白d. 百le trader trader now refuses to buy dolphins. In In another case ，some Cambodians managed to live-capture a juvenile dolphin in 1992. 百ley broug 'h t the animal to the vi11 age of Wem Kh am ，its tail tied to a 'h eavy rope ，組 d 凶ed to to sell it t 'h ere. However ，nobody wanted to buy it. After 出ree days ， the dolphin died and was left to float down the Mekong Ri ver.

Legal Status of Dolphins

In In Laos ，w 'h ere Irr awaddy dolphins 紅 e officially designated 部 a “自 s'h species" ， they

are are fully prot 民 ted by law ，組 d thehun 血 g ，capturlng and trading of Irr awaddy dolphins (血 e only only species of cetacean reported from Laos) is il1 egal and punis 'h able by fines rang 加gfrom

50 ，000 to 500 ，000 kip (US$ 65 to 650) an d/ or 3 months to one ye 紅 imprisonment (.AN ON. ， 164 164 弘N G. B Al RD AND BOUNHONG MOUNSOUPHOM

1991a). 1991a). In 1991 ，some Laotians were arrested for shooting four dolphins in Sekong (ANON ， 1991 1991 b). In Cambodia ，there does not appe 紅白be any specific legislation designed to protect dolphins. dolphins.

Dolphin Behavior

Between January and July ，1993 ， the dolphin population in 血ed 田 p water pools 泊

合'O nt of the villages of Hang Kh one and H 佃 g Sadam ，Champasak Pr ovince ，was observed for for at least a few hours a day approximately 6- 8 days a month. It appe 紅 'ed that there were

出ree or four groups of dolphins wi 由 2-8 members per group in the area d町 ing the whole time. time. In one c剖 ea group of approximately 17 組 imals w 出 seen ， probably a tempor ，紅 y aggregation aggregation of the smaller groups (Pam Stacey ，pers. comm. ， 1993). Pr obably not more 白血 30 dolphins were in the 紅白at any one time. It appears that the dolphins tend to move around

血e deep pool 紅 ea within an 紅白less than 1 km long and 0.5 km or less wide for hours at a time time during daylight hours (Fig. 1). 百ley are only rarely seen outside of the deep water area. In In May 1993 ， the dep 曲 of the water in 血e deep pool area in front of H 組 .g Kh one 組 d Hang Sadam was measured at 30 different spots throughout the. area where the dolphins are commonly seen. 官le pools were found to be approximately 10 ・30 m deep. During the monsoon season water levels rise from 10-20 m.

During During the monsoon season of 1993 ， the dolphins in 出e 釘 'ea could sti11 be seen ， but

白ey 0 負.en appe 釘 ed to disperse into other areas outside 白e deep pools ，and on some days 血ey could not be found at al l.百 le deep pool area has a very rocky bottom ，wi 白 somel 訂 ge rocks rocks becoming exposed 泊 the dry season. Th e deep water 釘 'ea is surrounded by seasonally flooded flooded forests. Because the water was very murky ，especially during 出.e monsoon se 部 on ， observing observing the dolphins' underwater movements w 田 not possible ， but it appeared 由at the animals animals trave11ed to one p副 of 出e pool ， fed for a number of minutes ，and 白en 回.v e11ed to ano 白er area to feed some more. Wh en not feeding ， the dolphins usually surfaced 由ree or fo 町 times insho 託 succession before disappearing underwater for 30 seconds to one minute. 百ley tended to surface more frequently while feeding.

Dolphin Feeding

Although Although it is difficult to determine a11 the species of that fish the dolphins feed on ，it is noteworthy 白紙large numbers of small cyprinids ，including Cirrhinus sp. (p a soi hooa lem in Lao) ， Cirrhinus siamensis (pa soi hooa po) ，Lo bocheilus melanotaenia (pa lung khon) ， Crossocheilus Crossocheilus cf reticulatus (pa dawk 加i) ， Paralaubuca cf か'P us (pa dtaep) ，and other species species are very abundant in and around the deep water 紅 e部 during the dry season ，when the dolphins 釘 .e probably more abundant in the deep water Hang Kh one and Hang Sadam 釘 ea. Villagers Villagers catch Cirrhinus sp. ，Cirrhinus siamensis ，Lo bocheilus melanotaeni ，仏 Crossocheilus cf. cf. reticulatus and other small species in large quantities using castnets and small mesh gillnets (2.5 (2.5 or 2.8 cm). Af ter water levels rise in July ， these species offish cannot be found in 白e IRRAWADY DOLPHI NS (O RCAELLA BREVIRO STR I S) IN SOUT I-I ER N LAO PDR 165

Figllr e 1. An lrr awaddy do lphin sllr fa cin g in a de巴p w al er poo l along the La o-Ca ll1 boclian bord er，a nd acro ss th e

M ekon g Ri ve r fro ll1 Han g Khon 巴 Vill age

Fig lll 巴 2. Th e I巴ll1 ain s 0 1' a Ba g arius )' arr elli ca lfi sh preye clllp onb y clolphin (s) a nd fOllncl tl oa tin g nea rH ang K hon e vill ag 巴，Lao PDR ，in Octob er，1 993. T he h ea cl we ighed 3 kg. 166 l AN G. B A IRD AND B OUNHONG M OUNSOUPH OM

Figure 3. An Irrawaddy do lphin th at d ied a ft er becoming entangled in a large-mesh gillnet near Hang Sadam Village, Apri l 1992.

Figure 4 . The skull and bo nes of an Irrawaddy dolphin, Wern Kham vill age, Lao PDR, April , 1992. IRRAWADY DOLPH 町 S (ORCAELLA BREVIROSTRIS) 町 SOUTHERN LAO PDR 167

area. 百lere is significant evidence ， based bo 白 on fish catch monitoring and villager inter- views ，出 at these sm a1 1 cyprinids migrate south ，entering flooded streams in Cambodia to spawn. spawn. We found that the females of these sp 田 ies were full of eggs at Hang Kh one in late June. June. As the water levels rise ，血 e sm a1 1 cyprinids travel SOUth from Hang Kh one and Hang Sadam ，and the dolphins become much more difficult to observe. At 血is time the dolphins seem 泊.g ly beg 泊 to disperse ，app 紅 'ently following and feeding on fish in some of the larger tributaries tributaries of the Mekong and Sekong Ri ver. Villagers reported 出at a dolphin became S住叩ded in sh a1 10w water in 白e Sesou Ri ver (a tributary of 白e Sekong Ri ver in Attapeu Pr ovince) in 1984 after apparently pen 柑 ating far up the river. 百le dolphins can again be eas i1 y observed in the Hang Kh one lH ang Sadam 紅 ea when water levels begin to go down in

October October and November. Th is coincides with the time of ye 訂 m 佃 Y fish species leave the 柑 eams andre 同m to the mainstream Mekong Ri ver.

A1 though Lao villagers in 血e 紅 'ea believe that small fish make up an important p制 of the the dolphins' diet ， they a1 so c1 aim that dolphins feed on most other species of sc a1 ed and non- sc a1 ed fish 踊 well. Whi1 e loc a1 s c1 aim that sm a1 1 cyprinids 釘 'e eaten whole ，出 ey a1 so report that that on1 y the lower halves of many 1紅 'ger species of fish ，some reaching over a meter long ，

紅 e preyed upon by the dolphins. V i11 agers often find the upper halves of big fish ，合 'om 血e dors a1 fin to 血e head ，float 泊g in waters that dolphins inhabit. Th ey sometimes retrieve and consume these upper ha1 ves of fishes ，if they 釘 e st i11 fresh. Over ha1 f of the 120 households at 出 e villages of Hang Kh one and Hang Sadam s町 veyed 泊 May 1993 c1 aimed 血ey had seem or person a1 1y re 凶 eved “dolphin prey leftovers" in 出ep 邸 t，and a1 most every household c1 aimed that dolphins on1 ye 鉱山e lower ha1 ves of large fish ， because m 姐 y species have long hard hard dors a1 and pector a1 spines. In In November 1993 a head and upper body of a large ca ぜish ， yarrelli (pa khae) ， was found floating in deep waters in 合ont of Hang Kh one (Fig. 2). 百le lower body right up to to the dors a1 and pectoral fin spines had been to ta1 1y eaten by a predator ，presumed to be a dolphin. dolphin. Th e remaining p釘 t of the fish weighed 3 kg ，and the whole fish probably weighed at at least 10 kg. Soon after ，a1 紅 ge Kryptopterus apogon (pa sangooa) was re 凶 evedfrom 白e same area. In December ，血 e head of a Pangasius hypophthalmus (pa sooay khaew) was retrieved.τ 'h e head 佃 d upper body of the fish ，from pector a1 spines up ，weighed 1 kg. In

February February 1994 ， another Bagarius yarrelli head was found ， weighing 1.2 kg. During the s創 ne mon 出， a head of a large Mystus microphthalmus (pa kh 即時)w 部 found by villagers ， but w 鎚 not not seen by the authors. ln all cases ， the lower body ，right up to 出e spines ，was totally consumed. consumed. Th e heads were tot a1 ly intact ，and there were no bite marks on the fish above the pecto ra1 fins. Dolphins probably ate the lower ha1 ves of a1 1 these fishes ， since few if 佃 y other other species would be capable of catching and consuming such large fish. Remains of yarrelli ，Mystus microphthalmus ，佃 d Cosmochilus ha ，初 andi were also been re- 凶 eved by the authors in 1994. Villagers Villagers c1 aimed that over 20 ye 紅 s ago dolphins were sometimes seen killing large Pangasius Pangasius sanitwongsei (pa lerm) “wi 白 a slap of their tails". According to many villagers at 168 168 lAN G. BAIRD AND BOUNHONO MOUNSOUPHOM

H 佃 g Kh one ，由 e dead fishes were not eaten by the dolphins after being killed. Th ese fish often often weighed over 100 kg. Th e locals ，after seeing the dead pa lerm floa 也Ig 泊白e water ， would go out 姐 d get the fish to eat themselves. Th e motive for the dolphins' app 紅 'ent attacks attacks on pa lerm are unknown. Since large Pangasius sanitwongsei are now extremely rare in in the Mekong Ri ver (none weighing ov ぽ 1 kg were caught 泊 Hang Kh on eIH組 gSadamin 19920r 1993) ，it s回 msu 凶ikely 白紙 there will be opportunities to observe such encounters in 血e forseeable future.

Dolphin Births

Wh en asked about 血et 加 eofye 紅 dolphins 紅 'e bom ，10% of the 120 household rep- resentatives resentatives interviewed in Hang Sadam and H 佃 g Kh one claimed 白紙 dolphins are bom in the the dry season months of April or May. A dead newly bom dolphin w 価問:covered near Hang Kh one Village in May 1993 by the authors.

A Hang Kh one local who is very familiar wi 由 the dolphins claimed ，and w 錨 backed up by a number of witnesses ，出 at he saw a dead newly-bom dolphin over 10 ye 釘 sagoin 白e 世y season. He took his long- 旬iled boat out to 切ke a closer look. Wh en he got a few meters away 合om the dead dolphin ，a number of adult dolphins st 紅 tedsw 紅 m 泊g around his boat ， presumed by the villager to be 釘y加g to keep him from getting close to 白e dead dolphin. He claimed 白紙 the got dolphins so close to the boat 白紙血ey almost capsized it so he gave up 句 ing to look at 白e dead dolphin and retumed to shore.

Thr ，曲 ts to Dolphins

In In Laos and Cambodia ，villagers have indica 旬d 白紙 dolphin populations have declined sig 凶ficantly in 血ep 踊 tfew decades. Dolphins are no longer ， or only very r紅 ely ， seen in many 釘 'eas 泊 bo 出 countries where 血ey were once apparently common. Several so 町 'ces of mortality mortality have been identified: bombs dropped 恒也e Sekong Ri ver during 血e In dochina War ，explosives used by Cambodians to catch fish ， being shot by soldiers and villagers ，and becoming accidentally caught and killed in large-mesh gillnets (Figs. 3 姐 d4). Th e aerial bombing of the Sekong Ri ver by the United States Air Force during the

In dochinese War apparently greatly affected 血， e river ，killing bo 血 fish and dolphins in 1ぽ ge numbers. numbers. However ，most locals living along the Lao/Cambodian border believe that 也e heavy use of explosives to catch fish by Cambodians is the main re 髄 on for decreasing dol- phin phin and fish pop 叫ationsin 血e Mekong Ri ver. In Cambodia ， the bombing began in 1979 after after Vietnamese soldiers arrived in 血e area with the fall of the Khm er Rouge. Since 白en ， explosives explosives have been used for fishing between December and June each year ，when water levels levels are low. A v 紅 iety of types of explosives are used ，some consisting of the insides of land land mines put 泊 soda pop cans. 百首 smethod is bo 出 destructive and w 儲飽和1，錨m 姐 yfish float to float the surface on1 y after becomming rotten ， or just sink to the bottom. In early 1993 ，10-

20bl 出 t!! were heard each day across the Mekong Ri ver 金om Hang Kh one. By July 1993 ， IRRA WADY DOLPH 別 S (ORCAEUA BREVIROSTRJS) 町 SOUτ 百ERN LAO PDR 169 however ，explosives fishing had stopped because of rising water levels and the lack of mi- grating grating fish ，which are often specifically targetted by explosives fishers.

La o villagers living near the Cambodian border claim that soldiers 企om the Cambo- dian dian People's Arm ed Forces (CP AF) promoted explosives fishing and sold explosives to fishers fishers before the new C 細 nbodi 佃 government w 部 established in late 1993. Al though the new Cambodian government formally prohibits explosive fishing and has spoken out 紺 ongly against against the method (CASEY ，1991) ，which is also very dangerous to 白e users themselves ， explosives explosives fishing was still widespread in Stung Treng in early 1994 due to a lack of effective law enforcemen t. Wh ile 白e season of explosives fishing normally lasts from December to June ，large- mesh gillnets have been responsible for dolphin mortality in other seasons. In May and June ，

12-18 12-18 cm mesh mono and multi-filament nylon gillnets 紅 'e used intensively to catch 1紅 'ge migrating migrating ca 出 sh Pangasius krempji. P. conchophilus and P. larnaudii. Between November and early January ， 18-25 cm mesh gillnets 釘 'e intensively used for large migrating and spaw 凶ng Probarbus jullieni and Probarbus labeamajor. Villagers 合om Hang Kh one 加 d

Hang Sadam report 血at dolphins are mainly entangled in gillnets in these two se 邸 ons. In both both seasons gillnets are placed near the surface in deep waters. Th e dolphins' ぬils tend to get get entangled in the large-meshed nets ，叩 d 血ey roll and turn ， usually resulting in fu 地 er entanglement entanglement and sometimes drowning. Bamboo traps ，hooks and lines the are main fishing gears used between July and Octo- ber ，whens 住ong river flow makes us of gillnets impractical. During the rest of the year bo 白

I紅 'ge-mesh and small-mesh gillnets are set much deeper th 姐 during May-June or Novem- ber-J 姐 uary ，and app ぽ 'ently pose minimal threat to dolphins ，who have only very rarely been known to become entangled in these deep set nets.

During During a 住ip to 血 e villages of Hang Kh one and Hang Sadam in April 1992 ，it w 部 reported 白at 6 dolphins had become accidentally entangled and died in gillnets used 泊也e

紅 'ea during the 16 ・month period between December 1990 and April 1992. Villagers re- ported 由at in le at 酪 tone case ，a dolphin could have been released alive had fisherfolk been

willing willing to cut 由e gillne t. Dolphins have been c加 ght in gillnets for up to 3 days before drowning. drowning. However ，villagers in 由earea 紅 'epoor 佃 d cannot afford to damage their nets to release release dolphins ，even though they don't want dolphins to die. Most people interviewed said 白紙 Cambodian fisherfolk almost always 町 to release dolphins which become entangled in their their gillnets alive ，but 紅 e success 釦1 in releasing them alive only about half of the 由ne.

Between May and December of 1992 ，villagers repo 託， ed 白紙 six dolphins died 泊也e Hang Kh one-Hang Sadam area. Th e authors observed three of the c紅 C 回 ses. Some were caught caught and died in gillnets ， but others 紅 e believed to have been killed by explosives used 泊 fishing. fishing. Between January and July of 1993 ， six more dolphins died in the Hang Kh on e/H ang Sadam area ，including the adjacent Cambodian villages of Wern Yang and Don Lan ga. Two were young 創 rimals ，includ 泊g one 由at was probably not more 出an one week old. Th e 170 170 弘 N G. B AlRD AND BOUNHONG MOUNSOUPHOM

youngest youngest dolphin had five distinctive ve 凶 bir cal 由 lines running across its body at regul 紅 intervals intervals (Figs. 5-8). 官官'ee of the six dolphins ，including the newbom an 加， al ，w 釘 erecov- ered ered and necropsies were performed. One of the six dolphins had been intentionally killed with with a knife by a Cambodian fisherman after 批 do ゆ in became 印刷gled in ag i1l net.

An othertwo 佃 imals had died after be 泊g caught 泊 Lao or Cambodian gillnets. Th e other three three dolphins prob 油， ly died after being blasted by ex がosives used in fishing. Dolphins caught caught in gillnets usually have cuts on 血eir tails or other p紅 ts of their bodies caused by 血e nets. 百lese marks c組 be easily observed if 也ean 加 als 釘 'e recovered soon after dying.

None of these 血ree dolphins had 佃 y marks of this kind on their bodies. They were all recovered recovered soon after dying.

In In Febru 紅 y，a Laotian fisherman cut his gi1l net to release a dolphin alive after 出e animal animal had become entangled in his ne t. Th e fisherman w 錨 la 飽r compensated for the dam- ages ages done to his net by the La o Community Fisheries and Dolphin Pr otection Pr oject 泊 accord 姐，ce with the net compensationldolphin release program established in cooperation between 血 e project and Hang Kh one and Hang Sadam vi1l agers. V i1l agers on the La o side of the the border are well aware of the net compensation fund progr 創 n，which they endorse.

A1 though gillnets are certainly a major threat to dolphins ，it appe 紅 S 白at dolphins 釘 e able able to detect and avoid these nets most of the time ，even 泊 high risk periods. Dolphins 紅 e often often seen swimming around large numbers of gi1l nets without becoming entangled in them.

V il1 agers believe that dolphins become entangled mai n1 y when they 紅 'e actively chasing fish.

In In recent years the number of large-mesh nylon gi11 nets used to 旬rgetl 釘 'ge fish in 血e Mekong Ri ver has greatly increased due to 血e high value of many foodfish species ，in- creased creased fish marketing oppo 此u凶ties brought on by better road access to remote 紅 'eas ， access to to ice ，and the widespread introduction of motorized boats used to tr: 佃 sport fish to buyers. Des がte the incre 蹴泊gi1l net use in recent ye 悩， local people in the Hang Kh one and Hang Sadam 紅 e部 appe 紅 determined to reduce the number of dolphin deaths ，and no dolphins were observed or reported to have died in the Hang Kh on eIH ang Sadam 釘 ea between Au- gust gust 1993 and March 1994. 百le reasons for 血is ap p:紅 ent decrease in dolphin mortality cannot cannot be determined ， although vi1l agers readily take credit for the improvemen t. 百le Lao Loom people living along the Sekong and Mekong Ri vers use a wide v組 ety of of fishing gears including various kinds ofbamboo 回， ps ，castnets ， hooks and lin 田， and gi 1ln ets to to catch fish. Some vi11 agers living along 也e Sekong Ri ver claim 白紙 dolphins 訂 'e able to break break away from small gi11 nets. In 1989 or 1990 ，a dolphin was reportedly caught and drowned accidentally 泊 a falling-door bamboo fish 位'ap ，called a “June" ，ne 紅白ev i11 age of Hang Ngow ， Attapeu Pr ovince. Thi sw 邸 the frrst time 組 yone had ever heard of a dolphin dying dying in a fish trap ，which vi11 agers do not consider to be dangerous to dolphins. In In 1990 ，two dolphins were shot by soldiers in Sekong Pr ovince. 百le soldiers were from 佃 0 血er area and apparently were not fi 捌 H 紅 wi 血 dolphins. 百ley apparently believed 白紙由e dolphins were serpents or crocodiles. In In 1991 ，v i11 agers did not repo 此 seeing any dolphins in the provinces of Sekong or Attapeu. Attapeu. However ， in April1992 ，a dolphin was apparently released u油釘med from ag i11 net IRR A W A DY D O LPHI NS (O R CAELLA BREVIROSTR1S) IN SOU T I-I ER N L AO PDR 171

二4 聖民、

Figllr e s. D ea d jll ve nil 巴 Irr awaddy do lphin fl oa lin g in Mekong Ri ve r，I-I ang K hone，La o PDR ，Ma y，199 3

Fig llI 巴 6. D ea d jll ve nil 巴 Irr awacldy do lphin nea r Han g K honev ill age ，Lao PDR ，Ma y，19 93 172 I AN G. B AIRD AND BOUNHONG MOUNSOU PH OM

Figure 7. Staff of Lao Community Fisheri es and Dolphin Protection Project moving a dead juvenile Irrawaddy dolphin usin g a small long-tail ed boat, Hang Khone vill age, Lao PDR, May, 1993.

Figure 8. A dead juvenil e Irrawaddy dolphin, its grey skin having already fa lle n off the body, May, 1993. IRRAWADY DOLPHINS (ORCAELLA BREVIROSTRIS) IN SOUTHERN LAO PDR 173

that that it had become entangled in ne 訂 Sekong town. Between July and October ，1992 ，two groups groups of dolphins ，one with six individuals and the other with two ，were sighted in the Sekong Ri ver 泊 Attapeu Pr ovince. Th e dolphins had apparently migrated up the Sekong Ri ver from Cambodia. Th e group of six dolphins reportedly stayed near Attapeu town for about about a month before going sou 出， app 訂 'ently back to Cambodia. 百le group of two dolphins travelled travelled up 出eSepi 加Ri ver from the Sekong Ri ver as far as Mai Village (about 60 km 仕om the the mouth of 出e Sepian Ri ver) ，where they were seen by a number of villagers. Villagers later later reported seeing them travelling south back into the Sekong River and presumably back to to Cambodia. In August 1993 ，a dolphin died in the Sekong River after becoming entangled in in a gillnet near Dong Jan Village ， which is about 15 km south of Sekong and not far from the mouth of 血e Senamnoi River. There There are several indications that the dolphins' food supply might be threatened. Fisherfolk Fisherfolk living throughout the range of the dolphin in southem Laos claim fish catches have have been declining sig 凶白C 組 tly every year over 由e past few years. Many claim that catches have have been reduced 20 ー25% per year. It is possible that this decrease in 白sh abundance has been been partially responsible for the decline in dolphins. Villagers in Laos have related that they are are concemed with the decrease in the numbers of dolphins and fish ，which they attribute to explosives explosives fishing and the blocking off of streams to catch fish in Cambodia and Laos. Overfishing Overfishing and the introduction of modem fishing instruments ，especially nylon gillnets ， have have also been cited as problems. Lao villagers are aware of many of the implications to the environment environment of unsustainable fishing practices ，and lament the that fact 印刷re generations may not be able to experience the sight of dolphins and rare species of fish. The Lao Com- munity munity Fisheries and Dolphin Pr otection Pr oject has worked with Lao villagers in a number of of communities to set up “no fishing conservation zones" in order to conse 円 e fisheries re- sources. sources. Locals have set up their own rules for managing these areas. Local people rely heavily heavily on riverine fisheries for food and income ，and decreases in fish catches 紅 e adversely affecting affecting large numbers of people in northeastern Cambodia and southern Lao PD R. Th erefore ，most Lao fishers feel the need for conservation measures. Irr awaddy dolphins are threatened and apparently already reduced in the Mekong Ri ver Basin. Basin. Any attempts to live-capture and enter any of the remaining Mekong Ri ver Basin population population into captivity ，however ，would be misguided. Dolphins usually experience a high mortality mortality rate once in captivity. Although breeding populations in the wild may a1r eady be very very small ，出 ey may still be viable. The best conservation s回 tegy is to 町 to reduce unnatu- ral ral mortality in the rivers.

OTHER CONSERV A TION CONCERNS

Irr awaddy dolphins inhabit some of the most vulnerable of aquatic habitats ，including tropical ，riverine ，estuarine and coastal areas (KL 町 OWSKA ， 1991). L 釘 ge-scale hydro-elec- tric tric dams proposed for the lower Mekong River ，including ones at S加 ng Treng and Sambor ， Cambodia ， are a serious conservation concern. If constructed ，either of these mainstream 174 IAN G. B Al RD AND BOUNHONG Mo 聞 SOUPHOM

dams would almost certainly adversely affect ，if not devastate ，populations of dolphins and migrating migrating fish species in 血e area. Furthermore ，1紅 'ge dams planned for the Sekong Ri ver and its its larger 凶butaries in Lao PDR would both reduce dolphin habitat and probably devastate a number of fish species ，including long-distance migratocy sp 田 ies ，such 錨 La beo cf. pierrei (pa (pa wa sooang) ，Mekongina erythrospila (pa sa ee) ， Cirrhinus molitorella (pa gaeng) ， Scaphognathops Scaphognathops spp. (pa pian) ，Gyrinocheilus pennocki (pa gaw) and many others (ROB 眠時，

1993). 1993). Many Cambodian and Lao fishers interviewed reported having seen 1紅 ge schools of these these species migrating down from the Sekong Ri ver into the Mekong Ri ver in December and January. Both wildlife and the livelihoods oflocal fishing communities would be jeop- ardized ardized by these 1紅 ge-scale dams ，if they 紅 'e allowed to be b凶lt. In creased motorized boat traffic in the Hang Kh one lH ang Sadam are a. brought on by increased 回 de and tourism ， could disturb the dolphins ，possibly causing them to leave the area. area. As boat traffic increases ， boat monitoring and regulating may become an important issue issue in terms of dolphin conservation in the area.

ACKNOWLEDGMENTS

百le s町 veys conducted in 1991 and 1992 were funded by E 紅白 Island Institute. 百le La o Community Fisheries and Dolphin Pr o飽ction project officially began in January 1993. E 紅白 Island Institute ， the Wh ale and Dolphin Conservation Society ，and the Asia Foundation have funded the work conducted by the project in cooperation with the Natural Resources Conservation Conservation and Watershed Management Division of the Lao Depar 佃 lent of Fores 町・ Special Special thanks are due to Suntorn A 曲ilakhorn (Hang Kh one Village) ，Pam Stacey (U 凶ver- sity sity of Victoria ，Canada) ，Ri chard Salter ， Robert Dobias and K1 aus Berkmuller (IUCN) ， Silavanh Silavanh Sawathvong ，Vengvongphet Sivanavong ，組 d Dr. Phoueyιao Department ofFor- es 句)， Greg Chapman ，Te 町y Warren and Jaloun (ln digenous Fish Development Pr oject- IDR C)， the Pr oject for Ecological Recovery and TERRA ， the Fisheries Department of C 鉱山odia. A number Vientiane government officials ，and many local government officials and villagers in the southern Lao provinces of Champasak ，Sekong ，and Attapeu who helped with with this work. 1 am grateful to them. Dr. Tyson R. Roberts assis 凶 in identifying most of 血， e fish species mentioned in this paper. Particular thanks are due to Pongsavaht Ki suvannalat ， Bongpaeng Pilyvanh 削 Sougan Pi 叫 ong ，who worked wi 白白epr' 吋ect and whose help with with the research done by the project w 部 invaluable. IRRA WADY DOLPH 別 S (ORCAE LlA BREVIROST Rl S) IN SOUTI 狙 RN LAO PDR 175

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