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Results of the IOSF FUNDED otter survey in Vo Doi Nature Reserve, Tran van thoi and U Minh iii fishery-forestry Enterprises, Southern Vietnam
Otter Habitat
All four Asian mainland otter species are globally threatened and need urgent conservation measures. The situation of Hairy-nosed otter (Lutra sumatrama) is the most alarmable. At present, this species is recorded in very few localities in Thailand (Kanchanasaka, 2000) and Vietnam (Nguyen Xuan Dang et al. 2000, 2001). There are also some signs of existence of Hairy-nosed otter in Cambodia but its exact localities has not yet confirmed (Poole, 2002). Therefore, survey to identify current distribution of Hairy-nosed otter is of utmost importance for its conservation actions.
Our surveys in 2000 and 2001 (Nguyen Xuan Dang et al. 2000, 2001) has found a small population of Hairy-nosed otter in U Minh Thuong Nature Reserve (09o2909o42N; 105o01 105o09E). Some signs of possible existence of Hairy-nosed otter in Vo Doi Nature Reserve (09o1136 09o1505N; 104o4306 104o5500E) are also found but still lack of confirmative evidence (Nguyen Xuan Dang et al. 2001). During March 2002, we conducted another survey to an area consisting of Vo Do Nature Reserve, Tran Van Thoi Fishery Forestry Enterprise (Tran Van Thoi FFE) and U Minh III Fishery- Forestry Enterprise (U Minh III FFE). The objectives of this survey are:
- To obtain exact species identification of otters in the area.
- To determine status and current threats to the otter population
- To identify recommendations for conservation and further research need of the otter population.
The survey was carried out from 28 February to 26 March 2002 by 3 scientists from Institute of Ecology and Biological Resources: Dr. Nguyen Xuan Dang, Dr Pham Trong Anh and Mr. Nguyen Truong Son.
We would like to express our sincerely thank to Dr. Paul Yoxon from International Otter Survival Fund, Prof. Dr. Padma de Silva from University of Peradeniya for their kind help in seeking fund and to International Otter Survival Fund (UK) and Colombus Zoo (USA) for kindly funding this survey. Our special thanks are to Mr. Nguyen Thanh Vinh Deputy Director of Department of Agriculture and Rural Development of Ca Mau Province, Directorates and staff members of Vo Doi Nature Reserve, Tran Van Thoi and U Minh III Fishery-Forestry Enterprises for their invaluable help during our works in the field.
Semi-structured interview with key informants
Interviews with selected key-informants such as forest guards, local hunters, forest utilizers, wildlife traders, etc. were carried out to get general information about otter fauna in the area and human impacts (hunting, trading, habitat disturbance) on the otter population. Questions were given in such way that did not encourage informants overstate the information or give wrong information. During this survey about 60 informants were interviewed.
Transect survey for direct observation of otters and observation of their signs
During survey time most of area was very dry. Water remained only in canals and some swamps therefore, survey transects followed canal system and swamps. Only where possible, short side transects coming into reedstands or Melaleuca forests were made. Direct observation of otter is ideal but due to thick vegetation cover possibility of direct otter sighting is very low. So otter's signs such as tracks, dropping (sprains), dens, etc. become main focus of the transect survey. Typical features and abundance of these signs can indicate the species belonging and certain ecological feature of the otter population (Kruuk et al, 1986, Kruuk et al., 1993, 1994)
Examining otter specimens and their remains in villages
Otters are sometimes kept by Vietnamese in their houses for pets or fish catching. Skins of hunted otters are usually kept for sale or for some kinds of medical use, as they believe. Alive captive otters and their remains provide valuable materials for exact species identification.
Waiting in key sites for direct observation
Much of efforts were made to get direct observation by waiting in key sites where otter usually goes out for foraging or swimming. Several direct observations were obtained during this survey
Camera-trapping
Three sets of camera-traps (Trailmaster TM1000/TM 1500, produced by Goodson and Associates, INC) were used.The camera-traps were set at 24 hour active; number of pulses to miss (-P) = 5, and camera delay CD = 2 minutes. The camera-traps were set for 18 days in 3 localities: near central Guardstation of Vo Doi Nature Reserve (9o1331N, 104o5626E), Plot TK-12 of Tran Van Thoi FFE (9o1225N, 104o5129E), Canal 90 of Tran Van Thoi FFE (9o1717N, 104o5423E).
Natural Mature forest in the Vo Doi Nature Reserve
Survey site consists of Vo Doi Nature Reserve, Tran Van Thoi FFE and U Minh III FFE. The area is situated in Ca Mau Province, South Vietnam, coordinates 9o11- 9o18N and 104o52 104o59E (Map 1). Total area is about 22,724ha, of which about 3,200ha mature natural Melaleuca forest and 10,000ha young Melaleuca plantation; the rest are Eleocharis and Phragmite grass meadows, some cultivated plantations and open swamps.
Vo Doi Nature Reserve was established in 1986, total area is 3,688.8ha. Forest covers about 3,195ha; other 494ha are open swamps and grassland. The reserve is divided into blocks by man-made canals, which connect with perimeter and outer canal system. Vo Doi Nature Reserve shares north boundary with Tran Van Thoi FFE and U Minh III FFE. The enterprises are carrying out no commercial forest logging, but forest re-planting, forest restoration and fish raising. These enterprises are suggested to unite with Vo Doi Natrue Reserve to establish larger Nature Reserve.
There are 3 main vegetation types in U Minh Ha area: Mature natural Melaleuca forests, Re-planted Melaleuca forest and seasonal inundated grasslands. Mature natural Melaleuca forest occurs only in Vo Doi Nature Reserve (about 3,195ha). The forest consists of predominance of Melaleuca cajuputi of 10 15m high and other trees in much lower density such as Ilex cymosa, Alstonia spathulata. The trees are usually covered by dense lianas: Stenochlaena palustris, Flagellaria indica, Scleria sumatrensis, etc. Re-planted Melaleuca plantations of various ages distribute throughout the area. The forests are usually clear with developed ground grass layer.
The inundated grasslands are predominant by Eleocharis dulcis. Other species such as Cyperus halpan, Cyperus polystachyos, Phragmites vallatoria, etc. occur in small number. In higher land predominate stands of Phragmites vallatoria; other common species are Cayratia trofolia, Vigna luteola, Panicum repens etc. Canals and swamps are usually covered by dense floating aquatic plants such as Eichhornia crassipes, Pistia stratiotes, Salvinia cucullata, Ipomoea aquatica.
Survey area is situated in humid tropical monsoon climate with 2 different seasons: Rainy season from May to October and Dry season from November to April next year. Majority of annual rainfall (about 2360mm) concentrates in rainy season. Consequently, dry season receives very little rainfall and forest fires occurred very often in the past. At present, Vo Doi Nature Reserve has a canal system to keep water in dry season to prevent forest fires.
Otter tracks in Vo Doi Nature reserve
As reported by local informants during our survey in 2000, before 1980, otters were very abundant in this area. Later, due to intensive hunting of otters for pelts, clearance of peatswamp forests and increase of human population have significantly declined the otter populations. However, otters still remain commonly in the area. They occur both in Vo Doi Nature Reserve and neighbour Tran Van Thoi and U Minh III FFEs. Two forms of otters are reported to occur in the area:
· "None-clawed otter" (Rai cai cui - in Vietnamese): smaller, body weight of about 2 - 3kg; fur is ground brown, claws are very small and do not show in their footprints; usually foraging in large group of up to10-20 individuals; major content of sprains is crab particles. These informations indicates existence of Asian small-clawed otter (Aonyx cinerea) and the species was confirmatively indentified by living individuals kept in the Zoo of Ca Mau City. Further information are catchings by Mr. Tu Chung - a forest guard of U Minh III FFE in October 1999 at Enterprises canal (9o1540; 104o5928) and by Mr. Nguyen Van Tai - a local resident in October 2000, at Tran Van Thoi FFE (9o1845;104o5323).
· "Clawed otter" (Rai ca mong - in Vietnamese): bigger, body weight of 7 - 10kg; fur is dark brown, claws are very long and always show in their footprints; foraging in small group of 2 - 4 individuals; sprains contains mainly fish scales and bones. These informations indicate existence of genus Lutra in the area and very likely Hairy-nosed otter (Lutra sumatrana). On the 1st November 2001 Mr. Nguyen Van Tung - a local resident caught one possible Hairy-nosed otter at Tran Van Thoi FFE (9o1845;104o5323). Due to lack of specimens the existence of Hairy-nosed otter in the area could not confirm in 2000 survey.
This survey was carried out in the end of dry season, most of area are dried out and water in the canals are very low exposing a band of bare mud along canal shores. This allowed us to better locate otter active area and to find more clear signs of Hairy nosed otter. Especially, during this survey one complete otter skin was obtained that allows to get exact identification of Hairy-nosed otter in the area.
The skin of Hairy-nosed otter was confiscated by Vo Doi Nature Reserve from a local resident Mr. Nguyen Hay who killed the otter in August 2001, at Canal K-300 (9o1153N, 104o5806E) of the Reserve (Map 2). The skin is complete and still in good status (see picture at Appendix). Measurements taken from the skin are: Head-body length - 78cm, Tail 44cm, biggest width 26cm, claws are very strong, sharp and curved, nose pad is covered by dense hairs. The skin is now kept at Department of Zoology, Institute of Ecology and Biological Resources, Hanoi, Vietnam.
In Vo Doi Nature Reserve tracks and sprains were found in several localities along the canals. The tracks clearly show claws and in some places, scratches made by claws are numerous and deep in the mud (see pictures in Appendix). This indicates that the tracks were made by Hairy-nosed otter. In 7 March 2002, at 16h05, we observed one Hairy-nosed otter foraging in grassland near small canal (9o1225; 104o5129) (Map 2). Searching in the area we found a number of fresh sprains and many tracks. One camera-trap was set here but no picture of otter could be taken.
In U Minh III FFE, tracks of Hairy-nosed otter were found in sector TK-93 (9o1439; 104o5603) close to Vo Doi Nature Reserve. But the tracks were not very fresh, about 1 month ago. Mr. Nguyen Van Thai staff member of U Minh III FFE informs that in 2001 he caught 2 Hairy-nosed otters in this place and one group of about 10 Small-clawed otters often forage in this area. Searching in other sectors of the Enterprise could not find any signs of otters.
In Tran Van Thoi FFE, survey was conducted in Sector 059 where more water remains. Other sectors are very dried and at high risk of forest fire, therefore, visit of foreigners was not allowed. Mr. Nguyen Minh Chuong and Mr Quach Van Son staff members of the Enterprise inform that during 2001, six (6) otters were caught in this area of them 2 Hairy-nosed and 4 Small-clawed otters. Other 4 otters (un-known species) were found dead in forest due to stucking in fishing traps of local farmers. Searching in this area we found a number of old tracks of both Hairy-nosed and Small-clawed otters in several localities. Many fresh tracks and several spraints of Hairy-nosed otter were found along Canal 90, especially, in fishpond near the Canal (9o1717; 104o5423), (Map 2). However, no signs of Small clawed otter were found. Camera-trap was set here but failed to get pictures of otters.
Although, tracks of Hairy-nosed otter (as well as Small-clawed otter) were found in various localities of survey area and in some places with high density, the number of otter seems very small. The otters do not stay in one place for long time, they move from one place to another in quite long distance for foraging. According to local informants, in each locality with otter tracks only about 2 5 Hairy-nosed otters are observed occassionally. We guestimate that not more than 100 Hairy-nosed otters survive in this survey area.
The signs of Small-clawed otter were very rare in comparison with those of Hairy-nosed otter. Possibly, during dry season when water becomes low Small-clawed otter move to large rivers or estuary areas.
Main current threats to the otter population are hunting and habitat disturbances by human activities.
- In survey area, only Vo Doi Nature Reserve receives protection status and wildlife hunting is mitigated by patrolling activities of the Reserves management force. In other 2 enterprises, although wildlife hunting is prohibited by law, but in fact, the hunting is still out of control. Otters often come to feed on fishes stucked in nets and traps which are very popularly used by local farmers. By this way, otters destroy the nets or traps causing conflict with fishing farmers. Therefore, the farmers always try to kill otters. In many cases otters themselves get stucked in the nets or traps and died or caught by the farmers. Furthermore, wildlife trade is also common in the area. Traders usually buy otters and their skins at relatively high price (20 40 USD/skin) in comparison with normal income of local farmers that encourages the people to kill otter at any favorable occasions. We were informed 13 otters killed during 2001, of them 5 are Hairy-nosed otters. Actual killings may be much higher.
- About 900 people now live in buffer zone of Vo Doi Nature Reserve and other several thousands live in neighbour enterprises. Their life relies on harvesting hydrozoological resources: fishes, snakes, turtles, mollusk, etc. and cultivating crops and vegetables. Their activities cause various negative impacts on the otter habitat such us destruction of otter refuges, reduction of otter food resources, environment polluting by pesticide, chemical fertilizers, killing otters etc. Risk of forest fire is also very high during dry season. Due to forests grow on thick peat layer (1.0 1.5m) the forest fires are difficult to stop. Several big forest fires happened in the past.
V. Recommendation
Confirmation of existence of Hairy-nosed otter makes the survey area important for protection of this globally threatened species. However, the otters are actually not protected in the area. Therefore, following actions must be taken as soon as possible:
· Tran Van Thoi and U Minh III FFEs should be aware about conservation of otters and apply strong measures to conserve otters as soon as possible. Better system of wildlife patrolling must be developed to control wildlife hunting and habitat disturbances in the enterprises.
· To promote conversion of Tran Van Thoi and U Minh III FFEs into protected area to enlarge Vo Doi Nature Reserve and provide otters and other wildlife species with large enough habitat and better protection status
· To conduct educational campaigns through posters, talks, newspapers, TV programmes, school seminars, etc. to increase awareness of local people on importance of oter conservation and their knowledge of national legislation on forest and wildlife protection.
· To train local enforecment forces of Vo Doi Nature Reserve, FFEs, local polices, custom on background knowledge and techniques of otter and wildlife protection.
· To carry out further survey in the area to assess status and ecological requirements of the otter population for development of relevant conservation measures.
· To carry out surveys in other wetland habitats of Vietnams Mekong Delta, especially Cau Mau province to locate other existing populations of Hairy-nosed otters for taking relevant conservation actions.
IOSF wants to continue to help Dr Dang and his team and will send over a represenative in 2003. Dr Dang wants to study another important area of Vietnam - the Ecosystem of the Song Trem, CA Mau Province. He require $9,526 for this research in 2003. If you can make a donation to this valuable work click
Reference
1. Foster-Turley, Macdonald S., and Mason Ch., 1990. Otters: An Action Plan for Their Conservation. IUCN/SSC, Gland, Switz.127p.
2. Hilton-Taylor C. (Compiler), 2000. 2000 IUCN Red List of Threatened Species. IUCN, Gland, Switzerland and Cambridge, UK.
3. Kanchanasaka B., 2000: The status of otters in Thailand and a note on the discovery of three Hairy-nosed otter (Lutra sumatrana) cubs. Proceeding of the workshop on Conservation and Public Awareness of Otters, Taiwan, 110-111.
4. Kruuk H., Conroy J. W. H., Glimmerveen U., Ouwerkerk E. J., 1986: The use of spraints to survey populations of otter Lutra lutra. J. Biol. Conservation, 35: 187-194.
5. Kruuk H., Kanchanasaka B., O'sullivant S., Wanghongsa S., 1993 Identification of tracks and other sign of three species of otter, Lutra lutra, L. perspicillata and Aonyx cinerea, in Thailand. J. Nat. Hist. Siam. Soc. 41: 23-30.
6. Kruuk H., Kanchanasaka B., O'sullivant S., Wanghongsa S., 1994 Niche separation in three sympatric otters Lutra perspicillata, L. lutra and Aonyx cinerea in Huai Kha Khaeng. Thailand. J. Biol. Conservation 69: 115-120.
7. MOSTE (Ministry of Science, Technology and Environment), 2000: Red Data Book of Vietnam. Publ. House Science & Technique, Hanoi, 408tr (in Vietnamese)
8. Nguyen Xuan Dang, Pham Trong Anh, Le Hong Tuyen, 2002: Results of otter survey in U Minh Thuong Nature Reserve, Kien Giang Province, Vietnam (1-30 March 2000). Un-publ.report.
9. Nguyen Xuan Dang, Hiroshi Sasaki, Pham Trong Anh, Le Hong Tuyen, 2001. Results of otter survey in U Minh Thuong Nature Reserve, Vo Doi Nature Reserve and its vicinity, Southern Vietnam (November 2000). Un-publ. Report.
10. Nguyen Xuan Dang, Pham Trong Anh, Nguyen Xuan Vinh, Nguyen Vu Khoi, Le Hong Tuyen, 2001. Hairy-nosed otter (Lutra sumatrana) in Vietnam: species re-discovery and conservation status. International workshop on Biology, Hanoi Vietnam 2-5 July 2001, V.1: 56-60.
11. Poole C.M., 2002 The first records of Hairy-nosed otter L. sumatrana from Cambodia. (in press).
12. Sivasothi N. Burhanudin H.M. Nor, 1994. A review of otter (Carnivora:Mustelidae: Lutrinae) in Malaysia and Singapore. J. Hydrobiologia (Belgium) 285:151-170.
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