Deep Bay 'visitors' depend on fishponds

PUBLISHED : Friday, 21 October, 1994, 12:00am
UPDATED : Friday, 21 October, 1994, 12:00am

I REFER to the letter headlined, 'Save the bay' (South China Morning Post, October 11).

The complexity of the Deep Bay ecosystem makes interpreting observations controversial between various ecologists. I agree with the letter's authors, Gary Grant and Nigel Wheatley that management of the remaining wetlands in Hong Kong is critical for the survival of wildlife, but I interpret their observations differently.

It is true that the majority of migrating birds using the Deep Bay area depend on the crabs, worms, clams, and snails that live on the mudflat. But the migrating birds are very diverse, comprising waders, ducks, gulls, egret-like birds, eagles, and songbirds. The mud of Deep Bay feeds most of the waders, ducks and gulls, but provides little food for the eagles, the songbirds, or the highly endangered black-faced spoonbills.

The past 'destruction' of mangroves in Deep Bay that Messrs Grant and Wheatley refer to may have increased biodiversity rather than decreased it, through the creation of fish and shrimp ponds.

For example, there are more insect species associated with fishponds than in mangroves. So the diversity associated with fishponds is not limited to birds: many of Hong Kong's remaining large wild mammals can be found around fishponds, including leopard cats, civets, mongooses, and otters.

These fishponds are essential to the survival of some of Deep Bay's threatened visitors, such as the endangered black-faced spoonbills which feed on recently drained fishponds during the winter.

The area of fishponds remaining means there are always some freshly drained at any one time since they are not all drained at once.

There are only some 1,200 hectares of fishponds left in the northwest New Territories. The Henderson development threatens 120 hectares while creating a reserve of about 40 hectares. The area and quality of the proposed reserve is doubtful for the wildlife that depends on fishponds. The Henderson development is only one of a series of encroaching developments, both private and governmental, depleting the area of wetlands.

The plans for the Lut Chau Nature Reserve, and the golf course at Nam Sang Wai illustrate the potential compatibility of conservation and development. We surely have not yet seen the best designs.

Once wetland is developed it is expensive and difficult to restore its conservation value. The Government can draw a policy line and conserve wetlands. The question is: how much do we value the existing wetlands and their wildness in terms of recreation, education, and our responsibility for stewardship? Stephen McChesney, Mai Po