Why Are the Yuen Long Fishponds Important for Birds and People?

The Yuen Long fishponds are not a nature reserve. They are a 1,500-hectare working agricultural zone where tilapia, grey mullet, and carp are raised for wholesale markets, and where the pond draining cycle inadvertently creates the mudflat conditions that tens of thousands of migratory shorebirds need. Without active fish farming, the shallow, nutrient-rich water bodies would dry out, scrub over, and lose their foraging value within a few seasons.

This patchwork of brackish and freshwater compartments on private land forms the buffer and connective tissue of the Inner Deep Bay Ramsar site. Access to the bunds that separate the ponds is entirely at the landowner's discretion. The conservation tension is straightforward: active fishpond management supports bird habitat, but abandonment triggers rapid vegetation encroachment that reduces feeding value to almost nothing. Grasp that dynamic and you can navigate this landscape without trespassing, and understand why it looks the way it does from the roadside.

A gei wai is a shallow, bunded pond with a sluice gate that lets in estuarine water from Deep Bay. Juvenile shrimp and fish enter naturally with the tide, feed on the detritus, and grow to marketable size without artificial feed. This low-input, seasonal method dates back centuries in the Pearl River Delta, with harvesting concentrated in autumn and winter.

When the Inner Deep Bay Ramsar site was designated in 1995, the gei wai inside the Mai Po Nature Reserve were a central justification. The listing recognises the wetland's global importance as a staging post on the East Asian, Australasian Flyway. But the designation covers private fishpond areas well beyond the WWF-managed core zone. Nam Sang Wai, Fung Lok Wai, and the pond network stretching north toward the border all form part of the functional ecosystem, even though they sit on private land with no public right of entry. The shrimp-farming tradition persists in a handful of ponds inside Mai Po, but across the wider district it has largely given way to intensive polyculture of tilapia and grey mullet. The ecological principle remains the same: a wet, actively managed pond is a bird feeding station. A dry, abandoned one is not.

The Inner Deep Bay Ramsar site covers 1,540 hectares of intertidal mudflat, mangrove fringe, gei wai, and commercial fishponds. Its boundary runs from the Shenzhen River in the north to the Tuen Mun River mouth in the south, and inland as far as the Castle Peak Road corridor in places. The Ramsar designation is a treaty-level commitment that constrains development proposals. It does not automatically turn private land into public open space.

Where You Can Stand and Where You Cannot

Within the Ramsar site, the Mai Po Nature Reserve is the only area with managed public access, and that access is by advance permit only. The rest of the pond zone, including the densest concentrations of fishpond bird habitat, is privately owned and actively farmed. Birders and photographers routinely scope the ponds from public roads like Tam Kon Chau Road and Deep Bay Road. Stepping onto a fishpond bund without permission is trespass. The landowner may be an individual, a family trust, or a corporation. Some tolerate quiet, responsible use of the bund tops. Others gate the access road and enforce it. There is no consistent rule, and there is no map that shows where you can walk. The operational definition of access is this: if the gate is open and no sign prohibits entry, you may proceed, but you must leave immediately if asked. If the gate is closed, it is closed for a reason.

Feature	Actively Managed Pond	Abandoned Pond
Water level	Fluctuates on a draining cycle; exposes mud at edges	Dries out completely or becomes reed choked
Invertebrate biomass	High; polychaetes, chironomid larvae, and shrimp in the water column	Low; terrestrialisation kills aquatic food chain
Bird species count (April migration)	30–50+ in a morning on a wet pond	Fewer than 10, mostly passerines in the scrub
Key wader species present	Black-tailed Godwit, Spotted Redshank, Marsh Sandpiper, Greenshank	Absent; no feeding substrate for waders
Management cost per hectare (annual)	Significant; aeration, sluice maintenance, feed, and stocking	Zero
Conservation outcome	Maintains Ramsar wetland function	Triggers encroachment and loss of foraging habitat

A commercial fish farmer drains a pond to harvest the stock, usually between October and March. As the water level drops, the bund edges and central depression expose wet mud. That mud is full of invertebrates living in the nutrient-rich pond sediment: polychaete worms, midge larvae, small crustaceans. Migratory shorebirds, notably Black-tailed Godwits, Spotted Redshanks, and Marsh Sandpipers, move onto the exposed mud and feed intensively. The farmer, having harvested the fish, refills the pond and restocks it. The birds move on to the next pond being drained. This rotational pattern, repeated across hundreds of ponds, creates a constantly refreshed food supply across the entire wintering and passage period.

The nutrition difference between an active fishpond and a natural mudflat is measurable. Pond sediment, enriched by fish feed and faeces, supports an invertebrate density several times higher than the adjacent Deep Bay mudflat. That is why waders are often more concentrated on commercial fishponds than on the intertidal zone, especially on a neap tide when the mudflat remains covered. The conservation implication is stark: if the farmer stops farming, the pond dries out permanently. Within 18 months, reed bed and terrestrial grasses colonise the basin. The invertebrate community collapses. The birds disappear. The visual change is a landscape that looks greener and more natural, but that is ecologically degraded. A working fishpond is a scruffy, utilitarian place with aerator paddles and plastic-pipe sluices. That scruffiness is what works.

Aquaculture in the Yuen Long wetlands began centuries ago as part of the coastal economy of the Tang clan villages. Early fish farmers converted mangrove fringe and tidal marsh into gei wai, using the natural tidal exchange to stock and harvest shrimp. By the mid-20th century, diesel pumps and concrete sluice gates allowed farmers to build ponds further inland, above the tidal reach. The industry shifted from extensive shrimp culture to intensive polyculture of grey mullet, tilapia, common carp, and bighead carp. The 1970s and 1980s saw rapid expansion of pond area as Hong Kong's population grew and demand for fresh fish rose. At its peak, the pond network covered more than 2,000 hectares across the northwest New Territories.

The 1990s brought two changes that reshaped the industry. The Ramsar designation in 1995 froze further pond conversion to other uses, locking in the existing landscape as a conservation asset. At the same time, competition from mainland Chinese fish farms, which had lower labour and land costs, made Yuen Long's small-scale pond operation economically marginal. Many farmers abandoned their ponds or sold them to developers. The ones that survive today do so on thin margins, often supplementing income with pond-based recreation like day-ticket fishing or photography access fees. The history is one of a functional landscape that became ecologically indispensable at exactly the moment its economic foundation began to erode.

Pondscape conservation in Deep Bay is the problem of keeping farmers on the land when the economics of aquaculture no longer support them. A working fishpond requires daily management: aerator maintenance, sluice gate operation, water quality monitoring, predation control from cormorants and herons, and the labour of harvesting. The return on that labour, at 2024 wholesale prices for tilapia and grey mullet, is low. The conservation value of the pond, on the other hand, is high. That gap is the core tension.

Schemes That Try to Bridge the Gap

Several schemes attempt to bridge it. The Hong Kong government's Environment and Conservation Fund has subsidised fish farmers to manage ponds in a bird-friendly way, including keeping water levels low on a rotational schedule that mimics the traditional draining cycle. WWF-Hong Kong runs a rice-fish farming project at Mai Po that revives an even older wetland agriculture system. But these schemes cover a fraction of the total pond area. The majority of the pondscape remains dependent on private land ownership decisions and the individual farmer's willingness to stay in a low-margin business. For the birder or the visitor, the practical consequence is this: the pondscape you see from the public road is not static. A pond that was full of waders in March may be dry and scrubby in September. That is not seasonal variation. It is the visible signature of a farmer who has stopped farming.

The entire fishpond zone from Nam Sang Wai north to the border is private land, subdivided into individual pond lots with registered owners. There are no public footpaths across the bunds, no waymarked trails, and no signage that invites you in. The public roads that traverse the area, Tam Kon Chau Road, Deep Bay Road, and the access road to Fung Lok Wai, are your viewing platforms. From a car window or a roadside verge, you can scope birds on the ponds without trespassing. Stepping over the drainage channel onto a bund is a legal crossing onto private property.

This does not mean the landscape is inaccessible. Some landowners tolerate quiet pedestrian access along the bund tops, particularly at Fung Lok Wai, where the road is ungated for the first few hundred metres and photographers regularly set up tripods at the pond edge for the Tin Shui Wai skyline reflection shot. At Nam Sang Wai, the bund-top path that loops around the pond mosaic is de facto open to walkers and cyclists, though the landowner could close it at any time. The key distinction is between tolerance and right. You have no right to be on a fishpond bund. If a farmer or landowner asks you to leave, you leave immediately and without argument. The conservation value of the pondscape depends on the goodwill of the people who own it. That goodwill is not inexhaustible.

Fung Lok Wai and Nam Sang Wai are the two areas most frequently visited by photographers and birders, and they operate under different access logics.

Fung Lok Wai: The Geometric Reflection Shot

Fung Lok Wai is accessed via a single road that turns off Deep Bay Road and runs east toward the Tin Shui Wai skyline. The first section of the road is ungated and offers a clear view across a series of commercial fishponds. This is the location for the classic reflection photograph of Tin Shui Wai's residential towers mirrored in still pond water, taken from a bund with no aerator ripple in the frame. Further in, a vehicle barrier restricts access to permit holders. The permit is a private arrangement, not a government scheme, and is obtained through photography clubs or by direct negotiation with the landowner.

Nam Sang Wai: The Tolerated Loop

Nam Sang Wai is accessed from Castle Peak Road via a narrow footbridge that crosses the Kam Tin River drainage channel. The bridge leads onto a bund-top path that loops through reed bed, fishpond, and a strip of poplar trees planted along the former riverbank. The loop is roughly 3 km and takes about an hour on foot. There is a sampan ferry crossing at the northern tip of the loop, operated at the boatman's discretion. The fare is not posted. The boat does not run in heavy rain or after dark. If you arrive at the ferry point and the gate is locked, you must backtrack the way you came, adding 20 minutes to the walk. Nam Sang Wai has no hides, no visitor centre, and no toilet other than a portable unit near the entrance. It is a working farm with a tolerated public route, not a park.

The fishponds are not isolated feeding stations. They are part of a connected Deep Bay ecosystem that includes the intertidal mudflat, the mangrove fringe, the reed beds along drainage channels, and the freshwater marshes at places like Lut Chau. Waterfowl feeding patterns shift across this mosaic according to tide, season, and disturbance. On a high tide, when the mudflat is covered, waders move inland to the fishponds to roost and feed. On a falling tide, they return to the intertidal zone to probe the exposed sediment. Dabbling ducks, such as Northern Shoveler and Eurasian Wigeon, use the fishponds throughout the winter, feeding on aquatic vegetation and invertebrates in the shallower ponds. Herons and egrets nest colonially in the fung shui woods behind village areas and commute daily to the pondscape to feed on small fish and frogs.

The nutrient flow runs both ways. Fishpond effluent, rich in nitrogen and phosphorus from uneaten feed and fish waste, drains into the channel network and eventually into Deep Bay. This eutrophication pulse can trigger algal blooms in the bay, which deplete oxygen and affect the bottom-dwelling invertebrate community that shorebirds rely on. The Environmental Protection Department monitors water quality in the drainage channels that connect the pondscape to the bay, and it varies seasonally with rainfall and pond draining schedules. The system is not a pristine wetland. It is a nutrient-enriched, human-managed, heavily modified ecosystem that happens to support an internationally significant concentration of birds. Understand it on those terms, rather than as a wilderness, and you understand why it works.

The visual density, the number of distinct pond compartments visible from a single elevated point, is highest from the upper floors of the Tin Shui Wai residential blocks. Those are not accessible to the public.

Fung Lok Wai: The Best Ground-Level View

The best ground-level viewpoint is from the Fung Lok Wai access road, looking east across the pond mosaic toward the Tin Shui Wai skyline. From here, on a clear morning between May and July, you can count 30 or more individual pond compartments in a single frame, each separated by a grass bund and each reflecting a different segment of the skyline. The shot requires a pond without an aerator running, because the ripple from the paddles breaks the reflection. The aerator closest to the road is often switched off by mid-morning; the ones further in may run continuously. Arrive by 07:30, check the pond surface from the roadside, and set up only when you have found still water.

Nam Sang Wai: The Pastoral Alternative

A secondary high-density viewpoint is from the pedestrian footbridge that crosses the Kam Tin River at Nam Sang Wai. Looking north from the bridge, the pondscape stretches in a flat plane to the horizon, with the Shenzhen skyline visible on a low-haze day. The visual texture from this angle is less geometric and more organic, with reed beds and tree lines interrupting the pond grid. For the photographer, Fung Lok Wai delivers the geometric abstraction. Nam Sang Wai delivers the pastoral landscape. Both are weather-dependent and both are on private land.