IUCN Management Category Unassigned

Biogeographical Province 4.06.01 (South Chinese Rainforest)

Geographical Location Lies in the north-west of the New Territories, bordering Deep Bay on the west and the People's Republic of China on the north. 22°29'-22°30'N, 114°02'-114°03'E

Date and History of Establishment First proposed as a nature reserve in 1968 by the Provisional Council for the Use and Conservation of the Countryside (Wholey, 1968) and declared a nature conservation area in June 1975, following which ponds in the area were purchased and managed by WWF-Hong Kong (Irving and Morton, 1988). Declared a Site of Special Scientific Interest on 15 September 1976. On 16 August 1978, Mai Po and all adjoining mangrove swamps were designated under the Wild Animals Protection Ordinance as an area to which access is restricted at all times.

Area 325ha. According to Irving and Morton (1988), the area is 380ha. Contiguous with Deep Bay Site of Special Scientific Interest (11,200ha) which was declared in 1986. Adjacent to Futien Nature Reserve, an 11.5km stretch of mangrove in the People's Republic of China.

Land Tenure Crown land, part of which is leased to WWF-Hong Kong

Altitude Sea level

Physical Features Occupying reclaimed land along the eastern shoreline of Deep Bay, Mai Po represents the largest estuarine area in Hong Kong, with mud flats, shallow shrimp ponds (208ha) and dwarf mangrove (85ha). Deep Bay is part of a structural depression, which extends in an arc from Castle Peak Bay to Sham Chun River and eastwards to Lo Wo, and is underlain by rocks of the Lok Ma Chain formation. Most of the deposition in this area has occurred in historical times (see Irving and Morton, 1988 for details). Deep Bay extends over 11,100ha at an average depth of 3m. The bottom of the Bay is covered with thick mud and silt. With a maximum tidal range of about 2.8m, large areas of exposed mud flats are exposed at low tide. Sham Chun River flows into Deep Bay from the north-east and, in turn, the Bay opens into Pearl River Estuary. Sediment is deposited by Sham Chun River and Yuen Long Creek, and probably also by flood tides from Pearl River. The inner shores of the Bay are fringed by dwarf mangroves, which aid accretion by trapping silt particles in their roots. In addition to natural deposition and uplift, there has been considerable reclamation around the Bay, some of which dates back 1,000 years. A system of sluices built in 1920 created 325ha for paddy farming. The shallow tidal shrimp ponds or gei wais that form the Mai Po Marshes were constructed in 1941-49 by impounding areas of mangrove with mud bunds. After a period of time the mangroves spread over the mud flats to the seaward side of ponds and new gei wais can be made. Deposition of silt in former gei wais creates a soil suitable for brackish water paddy and the reclamation cycle proceeeds. Many shallow gei wais have now been turned into deep fish ponds. Salinity varies considerably (2.5-29.5%) in the gei wais (Melville and Morton, 1983).

Climate Although Hong Kong lies just inside the tropics, the climate is temperate for nearly half the year. Mean annual rainfall ranges from around 1200mm to more than 3000mm, about 80% of which falls in summer. This is the longest season, lasting from May to September, with hot, humid and usually wet weather. Temperatures range from about 24°C to 32°C. September is the month in which Hong Kong is most likely to be affected by tropical typhoons. These originate from near the Philippines and approach from a south-easterly direction. Winter, lasting from November until February, is cold and dry. Temperatures commonly range from about 13°C to 24°C but sometimes drop below freezing point on high ground and in the New Territories (Thrower, 1984; Ismail, 1987). Meterological data are not available for Mai Po.

Vegetation The gei wais are colonised by a pioneer community of mangroves, with Kandelia candel progressively replaced by shorter trees of a mixed stand of grey mangrove Avicennia marina and brown mangrove Aegiceras corniculatum towards the sea. The seaward fringe of the Mai Po mangroves is dominated by prickly mangrove Acanthus ilicifolius. With their decline in use and maintenance, the kei wais have become much more densely colonised by plants, with Phragmites sp. dominant in many places. Mangrove fern Acrostichum aureum and coastal plants, such as the shrub Clerodendron inerme, the grass Paspalum distichum and sedge Cyperus malaccensis, occur on the bunds (Melville and Morton, 1983).

Fauna Larger mammals such as common otter Lutra lutra, formerly plentiful, and crab-eating mongoose Herpestes urva have disappeared from the Deep Bay area due to increasing human pressures. One otter, however, was present in the 1985/1986 winter after an absence of records for 30 years. The largest mammal present is greater bandicoot-rat Bandicota indica which appears to be numerous. Brown rat Rattus norvegicus is common and house shrew Suncus murinus has been found away from human habitation on bunds. Japanese pipistrelle Pipistrellus abramus is often seen hawking for insects on the marshes; less frequently seen is dog-faced fruit bat Cynopterus sphinx (Melville and Morton, 1983; Scott, 1989).

The Deep Bay area is best known for its avifauna. Of the 400 species currently known in Hong Kong, some 250 have been recorded from this area, of which over 100 are rarely found elsewhere in the country (Melville and Morton, 1983). Threatened species include Dalmatian pelican Pelecanus crispus (V), which has been gradually declining from 84 wintering in 1971 to 33 in 1987, peregrine falcon Falco peregrinus (V), eastern white stork Ciconia (ciconia) boyciana (E), an occasional winter visitor, Asian dowitcher Limnodromus seripalmatus (R), which is a regular passage migrant with over 340 recorded in recent years, spotted greenshank Tringa guttifer (I), which has been recorded twice or possibly three times, and the rare spoon-billed sandpiper Eurynorhynchus pygmeus, a passage migrant. The area is the only known wintering ground of Saunder's gull Larus saundersi and also supports up to 30 black-faced spoonbills Platalea minor, a species in need of special attention (Karpowicz, n.d.). The total number of birds wintering in the Deep Bay area has increased dramatically, from about 13,000 in 1979 to 38,000 in 1987. Further details of the avifauna are given in Scott (1989).

The more common species of snake include common rat snake Ptyas mucosus, many-banded krait Bungarus multicinctus and Chinese cobra Naja naja. Most notable is mangrove snake Enhydris bennetti, which has a very restricted distribution (Melville and Morton, 1983).

Fish diversity is low due to the variable salinity of the water. Tilapia mossambica (introduced from East Africa) is predominant in the gei wais, but a close second is striped mullet Mugil cephalus. A number of other fish are also harvested. Mudskippers, namely Periophthalmus cantonensis (dominant species) and Boleophthalmus boddaerti abound in the soft mud (Melville and Morton, 1983). Among the invertebrate fauna, crustaceans and molluscs are probably the most important mangrove associates. Shrimps, of the genera Penaeus and Metapenaeus, are harvested from the gei wais and oysters are cultivated along the intertidal mud flats of Deep Bay. The crab Chiromanthes maipoensis is endemic to Mai Po (Melville and Morton, 1983).

Cultural Heritage Earliest human presence in the area dates back some 6,000 years. Artifacts and historical accounts suggest that these aboriginal people derived their livelihood mainly from the sea. While fishing remained important throughout historical times, the development of agriculture on the plains adjacent to Deep Bay was a feature of Sung Dynasty migrations. The last of the major immigrant families to settle in the area were Mans. Arriving towards the end of the 13th century, they established a village at San Tin. Gradually, they drained and cultivated the marshes, the same techniques being used to create the gei wais or shrimp ponds of Mai Po in the early 1940s (Irving and Morton, 1988). The intertidal mud flats of Deep Bay have been used to cultivate oysters for at least 170 years and possibly for as long as 700 years. Annual production has declined from around 1,000 tonnes in the late 1950s to a few hundred tonnes in recent years, probably the result of reduced manpower as young people turn to more profitable employment, as well as changing environmental conditions in the Bay (Melville and Morton, 1983).

Local Human Population There has been considerable urban growth around Deep Bay since the Japanese occupation of Hong Kong in 1942. Development of Luen Long into a 'New Town', some 4km to the south of Mai Po, began in 1978 and by 1987 its population had reached 86,500. A second 'New Town' is planned for nearby Tin Shui Wai; this will house 135,000 people. Another significant urban development began in 1975 with the construction of a housing estate (Fairview Park) for some 30,000 people on 116ha of land adjacent to the eastern boundary of Mai Po (Irving and Morton, 1988).

Offshore fishing, mostly bottom trawling, inshore trawling for small clams, oyster and shrimp cultivation, and fish farming are major activities, while other traditional industries such as salt panning, lime burning and brick making have virtually ceased (Irving and Morton, 1988). About 50% of the gei wais and fish ponds in the area are operated by local fishermen (Department of Agriculture and Fisheries, pers. comm., 1989),

Visitors and Visitor Facilities Permits to visit Mai Po can be obtained upon written application to the Director of the Agriculture and Fisheries Department. In 1988, there were over 25,000 visitors. A new wildlife education centre, opened in 1986 by HRH The Duke of Edinburgh (Anon., 1987b), provides simple laboratory facilities. Its establishment was first recommended by Sir Peter Scott (1964), and a proposal subsequently developed by Goodall (1982) and Axell (1983).

Scientific Research and Facilities Most research has been concentrated on recording flora and fauna. The waterfowl have been regularly counted by the Hong Kong Birdwatching Society for many years. Studies of migratory species are beginning to reveal details of their annual movements (Melville and Morton, 1983). The site has considerable potential as a research and monitoring station for migratory birds using the China coast as a flyway: a route little known to ornithologists and with few protected areas along the way (Sir Peter Scott, in Melville and Morton, 1983). Pollution of Deep Bay is under study (WWF-Hong Kong, 1989).

Conservation Value Mai Po is the only extensive conservation area of international importance in Hong Kong. It harbours the largest area of mangroves remaining in the country. Together with the adjacent Futien Nature Reserve in China, it is a strategically important feeding ground for shore birds that breed in Siberia and winter in south-east Asia and Australia, some species migrating distances of over 7,000km (Melville and Morton, 1983; Scott, 1989).

Conservation Management The site has been designated an area of restricted access to prevent its development without prior reference to the Agriculture and Fisheries Department. Being man-made and subject to natural processes of erosion, the marshes need careful management. This is largely the responsibility of WWF-Hong Kong, which first took control of managing the site as a de facto nature reserve in 1983, with the purchase of the lease of 115 acres (46.5ha) of gei wais. By mid-1990, WWF-Hong Kong had acquired about 90ha of the marshes. An education centre has been constructed with funds raised by WWF-Hong Kong A Joint Working Group, involving WWF-Hong Kong and Guanadona Province Forest, is responsible for integrating the management of Mai Po and Futien Nature Reserve. Existing proposals include the acquisition of all remaining marsh by WWF-Hong Kong, the establishment of a residential Field Studies Centre (now largely funded), and the establishment of a captive waterfowl collection (partly funded). WWF-Hong Kong has recommended to the Government of Hong Kong that Mai Po and Inner Deep Bay be designated as wetlands of international importance under the Ramsar Convention (Viney, 1985; Evans, 1986; Scott, 1989).

Management Constraints Increasing urban development and associated flood control programmes are likely to lead to changed water movement patterns and increased pollution, but agricultural waste input is expected to decrease. A 65 million ton capacity rubbish dump is planned for the edge of Deep Bay, principally to take domestic waste, although it is expected to take hazardous waste in the future. The Chinese authorities plan to dredge and straighten the Shenzhen River to assist in flood control and to improve navigability. This is likely to have an adverse effect on the water quality of Deep Bay, as industrial and agricultural wastes that have settled on the river bed will be stirred up and flushed into the Bay. In May 1987, the Chinese announced plans to build an airport on reclaimed land on the north shore of Deep Bay. The construction of the airport would have destroyed about 23% of the tidal mudflats, and the runway would have come within seven kilometres of Mai Po. In early 1988, however, the Chinese Government announced that an alternative site for the airport had been chosen in Bo An County, some distance to the north-west of Deep Bay on the edge of Pearl River (Anon., 1988; Scott, 1989).

Staff Some seven staff from the Agriculture and Fisheries Department are responsible for day-to-day patrol duties in the 'nature reserve'. WWF-Hong Kong deploys 10 permanent staff and, from time to time, voluntary workers to manage its leased land.

Budget HK$ 6.8 million (US$ 872,000) has been donated towards the Residential Field Studies Centre and HK$ 2 million (US$ 256,000) towards the captive waterfowl collection.

Local Addresses

No information

References

Anon. (1987a). Pledge to save Hong Kong's threatened wetlands. New Scientist 1572: 22.

Anon. (1987b). International action and education - the Mai Po example. WWF News 45: 4-5.

Anon. (1988). Airport site re-located from major wetland. WWF News 52: 8.

Axell, H.E. (1983). Mai Po Marshes. Proposals for development as a nature reserve and education centre. WWF Hong Kong, Hong Kong. Unpublished report.

Evans, L. (1986). Hong Kong's other colony. Telegraph Sunday Magazine 524: 54-61.

Goodall, S. M. (1982). Report on the Feasibility of Mai Po Marshes as a Wildlife Education Centre. WWF Hong Kong, Hong Kong.

Irving, R. and Morton, B (1988). A geography of the Mai Po Marshes. Hong Kong University Press, Hong Kong. 58 pp.

Ismail, A. (1987). Hong Kong 1987. Government Printer, Hong Kong. 364 pp.

Karpowicz, Z. (n.d.). Wetlands in East Asia - a preliminary review and inventory. ICBP, Cambridge. Unpublished report. Pp. 30-32.

Melville, D.S. and Morton, B. (1983). Mai Po Marshes. WWF Hong Kong, Hong Kong. 36 pp.

Oldfield, S. (1987). Fragments of Paradise. A guide for conservation in the UK Dependent Territories. Pisces Publications, Oxford. 192 pp.

Scott, P. (1964). Report on a brief visit to Hong Kong in October, 1964. Hong Kong University. Unpublished report. 3 pp.

Scott, D.A. (Ed.) (1989). A directory of Asian wetlands. IUCN, Gland, Switzerland and Cambridge, UK. 1,181 pp.

Viney, C. (1985). Big birds race nets over half a million dollars for Mai Po. Wildlife, WWF Hong Kong 3(2): 1.

Wholey, J.W. (1968). The countryside and the people: report of the Provisional Council for the Use and Conservation of the Countryside. Government Printer, Hong Kong.

WWF-Hong Kong (1989). John Swire scholarship in wetland ecology. Wildlife 7(1): 3.

WWF Project No. II 3619. Hong Kong - Establishment of a nature reserve at Mai Po Marshes.

Date September 1987, updated December 1990