Six months for people, six months for birds
The fortunes of the black-faced spoonbill are closely connected to aquaculture practices. Traditionally, milkfish have been raised along the Tainan coast in shallow ponds, and the slack period between fish breeding cycles coincides with the spoonbill’s overwintering season, allowing the birds to feed on small fish and crustaceans remaining in the ponds after the milkfish are harvested. However, the higher-value groupers and clams that have been increasingly popular with fish farmers in recent years require deeper ponds, and are reared intensively all year round with no rest period, in operations that generate large amounts of effluent. Because the black-faced spoonbill is a wader, the depth of the traditional shallower milkfish ponds was well matched to its feeding habits, as was the timing of the milkfish rearing cycle. But the trend toward year-round intensive aquaculture in deep ponds has greatly restricted the spoonbill’s food sources, threatening the birds’ survival.
“Let people use the ponds for half the year, and let birds use them for the other half.” From April to October, fish farmers traditionally raised milkfish in shallow ponds at low densities and with minimal inputs. Then, from October to April, it was the season when the black-faced spoonbill overwinters in Taiwan. After the milkfish were harvested, the water levels in the ponds were lowered, and the birds were able to feed on the assorted small fish and crustaceans that remained in the bottoms of the ponds. This seasonal cycle dates back 300 years to when the Dutch first introduced milkfish farming to Taiwan. It embodies the concept of preserving an organic, dynamic and sustainable cultural landscape, an idea that also implies ecological protection.
Describing the experimental “bird-friendly aquaculture” operations on the Qigu Campus of National University of Tainan, Associate Professor Wang Yi-kuang of the Department of Ecology and Environmental Resources says: “The whole experiment was mainly based on the seasonal nature of shallow-pond milkfish farming, which operates from April to around the end of October. After the fish were harvested, we undertook comparative experiments with lower water levels.” The comparisons showed that lowering the water levels had a significant effect on the use of the ponds by black-faced spoonbill and other waders such as great and little white egrets, as well as some shorebirds that forage on beaches and exposed mudflats at low tide. The result of several years of experimenting was that adjusting the water level in fish ponds had a clear impact on the numbers of birds that gathered there.
From April to October, fish farmers traditionally raised milkfish in shallow ponds at low densities and with minimal inputs. Then, from October to April, it was the season when the black-faced spoonbill overwinters in Taiwan. After the milkfish were harvested, the water levels in the ponds were lowered, and the birds were able to feed on the assorted small fish and crustaceans that remained in the bottoms of the ponds.