Shorebirds of the Yellow Sea
Importance, threats and conservation status
Wetlands International, 2002
ISBN 90 5882 009 2
Surveys conducted during the last 12 years in China and Korea show that the extensive intertidal areas and near-coastal wetlands of the Yellow Sea support very large numbers of migratory shorebirds. It is estimated that at least 2 000 000 shorebirds use the region during northward migration, this number being approximately 40% of all the migratory shorebirds in the East Asian-Australasian Flyway. Large numbers are also present during southward migration when perhaps 1 000 000 shorebirds pass through the region.
A total of 36 shorebird species have so far been found to occur in internationally important numbers at one or more sites in the Yellow Sea, representing 60% of the migratory shorebird species occurring in the Flyway. Two of the species are classified as globally threatened, the Spotted Greenshank Tringa guttifer and Spoon-billed Sandpiper Eurynorhynchus pygmeus, whilst two are near-threatened, the Eastern Curlew Numenius madagascariensis and Asian Dowitcher Limnodromus semipalmatus.
Whilst the majority of birds use the region's wetlands as migration staging areas, seven species also occur in internationally important concentrations during the non-breeding season and five species breed in internationally important numbers.
The importance of the Yellow Sea is demonstrated by the fact that it supports more than 30% of the estimated flyway breeding populations of 18 shorebird species during northward migration; for six of the species the region carries almost the whole flyway breeding population at this time. It is highly likely that the great majority of Spotted Greenshank and Spoon-billed Sandpiper use the Yellow Sea during both northward and southward migrations. Approximately 80% of the estimated flyway population of the Eastern Curlew uses the Yellow Sea on northward migration and 40% of the Asian Dowitcher population.
Whilst the South Korean coastline has been well covered, both spatially and temporally, only about one-third of the Chinese intertidal area has been surveyed at least once, with most of the counting having been conducted during northward migration. Very little information is available from North Korea. Improved coverage of the Chinese and North Korean coasts would probably lead to increases in the estimates of the numbers of shorebirds using the Yellow Sea at different times of the year. Additional surveys would certainly lead to the identification of more internationally important species and sites. Thus, improved coverage of the unsurveyed parts of the coastline should be a high priority.
Shorebirds employ a wide variety of strategies in their use of the Yellow Sea. Some occur in high concentrations at a relatively limited number of sites, whilst others are distributed over a large number of sites with few major concentrations. The strategies of most species lie in between these extremes. Conservation management of the different species will need to take into account the varying ways in which shorebirds use the Yellow Sea wetlands.
Twenty seven sites have been identified around the Yellow Sea coastline at which at least one shorebird species has been recorded in internationally important numbers. Ten of these sites are located in China, one in North Korea and sixteen in South Korea. Six of the ten Chinese sites and the North Korean site are within Protected Areas, whilst a small part of one of the 16 South Korean sites is a Protected Area.
The sites exhibit a great diversity in the shorebirds they hold. Half of the sites support at least five species in internationally important numbers, whilst six sites carry 15 or more. Five sites have shorebird counts greater than 100 000 on northward migration, whilst one supports almost 250 000 shorebirds on southward migration.
The rapid growth of the human populations and economies of China and South Korea is causing serious loss and degradation of coastal habitats.
Approximately 37% of the intertidal areas existing in the Chinese portion of the Yellow Sea in 1950 and 43% of those in the South Korean part in 1917 have been reclaimed to date. China has plans to reclaim a further 45% of its current mudflats and South Korea an additional 34%. The two largest rivers flowing into the Yellow Sea, the Huang He (Yellow River) and Chang Jiang (Yangtze River), are undergoing significant changes that will greatly reduce the amount of sediment input and it is predicted that future loss of intertidal areas will occur at an increasing rate due to the combined effects of reclamation and reduced accretion.
The declining river flows and high levels of pollution are leading to reduced benthic productivity and, thus, a decline in food supplies for shorebirds. Human disturbance, by affecting feeding and roosting birds, and competition, through unsustainable harvesting of benthic fauna, may also have a serious impact on shorebirds.
The adverse effects of the various threats being encountered by shorebirds in the Yellow Sea are most significant during northward migration when shorebirds are not only preparing for their final long flight into the breeding grounds but also gaining additional reserves to sustain them during the period immediately after arrival, when feeding conditions may be poor.
Of particular concern is the ongoing reclamation of the Mangyeung and Dongjin estuaries as part of the 401 km2 Saemangeum Reclamation Project. These estuaries are the most important sites in South Korea during both northward and southward migration in terms of both maximum counts and numbers of internationally important species supported. During the northward migration period, the two estuaries jointly carry 30% of the Great Knot Calidris tenuirostris breeding population. The estuaries also support the most significant concentrations within the Yellow Sea of the endangered Spotted Greenshank and vulnerable Spoon-billed Sandpiper during southward migration. Between them the two estuaries support the highest recorded concentrations in the Yellow Sea during northward migration of three species, and during southward migration of seven.
Achieving effective conservation of migratory shorebirds and their wetland habitats will be particularly challenging around the Yellow Sea coastline. The traditional approach to nature conservation of creating a network of Protected Areas, with restrictions on human activities, is inappropriate due to the very extensive nature of the intertidal areas in the region and the high dependence of the local communities on intertidal resources.
Successful shorebird conservation will depend on the adoption of harmonised national policies and plans for the wise and sustainable use of the intertidal and sub-coastal areas of the Yellow Sea. Local community support will be an essential factor in the successful development and implementation of these policies and plans.
The exceptional importance of the Yellow Sea biodiversity, both on a global scale and as a resource shared by China, North Korea and South Korea, makes it highly desirable that conservation should be implemented on an ecoregion-basis. The challenge is to facilitate a process in which a Yellow Sea ecoregion management plan is adopted and implemented by the three Governments. Only then will the future for the globally important biodiversity of the Yellow Sea become brighter and the prospects of the millions of shorebirds passing through the region more promising.