South China Sea
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LME 36: South China Sea

Bordering countries:

Brunei Darussalam, China, Hong Kong, Indonesia, Macao, Malaysia, Philippines, Singapore, Taiwan, Viet Nam

LME total area:

5,660,985 km²

LME overall risk:

This LME falls in the cluster of LMEs that exhibit low to levels of economic development (based on the night light development index) and high pollution from plastic debris.
Based on a combined measure of the Human Development Index and the averaged indicators for fish & fisheries and pollution & ecosystem health modules, the overall risk factor is very high.

Productivity

Chlorophyll-A:

The annual Chlorophyll a concentration (CHL) cycle has a maximum peak (0.270 mg.m^-3) in January and a minimum (0.139 mg.m^-3) during May. The average CHL is 0.185 mg.m^-3. Maximum primary productivity (295 g.C.m^-2.y^-1) occurred during 2007 and minimum primary productivity (263 g.C.m^-2.y^-1) during 2013. There is a statistically insignificant increasing trend in Chlorophyll of 2.96 % from 2003 through 2013. The average primary productivity is 285 g.C.m^-2.y^-1, which places this LME in Group 3 of 5 categories (with 1 = lowest and 5= highest).

Primary productivity:

Sea Surface Temperature:

From 1957 to 2012, the South China Sea #36 has warmed by 0.80°C, thus being on a threshold between Categories 2 and 3 (fast-to-moderate warming LME). The thermal history of the South China Sea is linked to that of the Gulf of Thailand LME #35. Interannual and decadal variability in the South China Sea are relatively small, <0.5°C. The observed stability of the South China Sea can be partly explained by the existence of the so-called South China Warm Pool (Li et al., 2007). The South China Warm Pool changes seasonally and inter-annually (He et al., 2000): It grows in summer; shrinks and retreats to the southwest in winter, and it is modulated inter-annually by the ENSO (El Niño-Southern Oscillation). The all-time maximum SST exceeded 28.6°C in 1998, coinciding with El Niño.

Fish and Fisheries

Reported landings from the South China Sea LME are in the order of 6 million t, although substantial uncertainty is associated with these high figures. The marine fisheries target groups that include tuna, billfishes, mackerels and sharks for the pelagic species, and a huge array of demersal fish and invertebrates, especially penaeid shrimps.

Annual catch:

The steady increase of the reported landings, from 490,000 t in 1950 to a peak of over 6 million t in 2001 is primarily due to a significant increase in the landings of unidentified fishes (included in ‘mix group’), which account for two-thirds of the landings in recent years. In general, a high proportion of unidentified fishes in landings statistics is a symptom of deficiencies in a reporting system.

Catch value:

Due to the large increase in the reported landings, the value of the landings also rose steadily, reaching around 10 billion US$ (in 2005 real US$) in the recent 5 years (2006 – 2010).

Marine Trophic Index and Fishing-in-Balance index:

The trends of both MTI and the FiB index until the mid-1980s are suggestive of a ‘fishing down’ in the food web with a limited geographic expansion of fisheries. The trends of these indices from the mid-1980s on suggest that the landings statistics for the LME include either catches made outside the LME, which would also explain why the PPR for the fisheries in the LME is so high.

Stock status:

The Stock-Catch Status Plots indicate that almost 40% of the stocks in the LME are collapsed or overexploited. However, the majority of the catches are supplied by fully exploited stocks. Such diagnosis is probably optimistic, and is again likely a result of the high degree of taxonomic aggregation in the underlying statistics.

Catch from bottom impacting gear:

The percentage of catch from the bottom gear type to the total catch fluctuated between 12 and 24% from 1950 to 2010. This percentage fluctuated around 22% in the recent decade.

Fishing effort:

The total effective effort continuously increased from around 45 million kW in the early 1950s to its peak at 270 million kW in 1999.

Primary Production Required:

The primary production required (PPR) to sustain the reported landings in this LME is increasing with the reported landings, and since 2000, it is over 60% of the observed primary production, yet another indication that the reported landings from this LME may be unrealistically high.

Catch potential projections (under global warming):

Pollution and Ecosystem Health

Pollution

Nutrient ratio, Nitrogen load and Merged Indicator:

Human activities in watersheds are affecting nutrients transported by rivers into LMEs. Large amounts of nutrients (in particular nitrogen load) entering coastal waters of LMEs can result in high biomass algal blooms, leading to hypoxic or anoxic conditions, increased turbidity and changes in community composition, among other effects. In addition, changes in the ratio of nutrients entering LMEs can result in dominance by algal species that have deleterious effects (toxic, clog gills of shellfish, etc.) on ecosystems and humans. An overall nutrient indicator (Merged Nutrient Indicator) based on 2 sub-indicators: Nitrogen Load and Nutrient Ratio (ratio of dissolved Silica to Nitrogen or Phosphorus - the Index of Coastal Eutrophication Potential or ICEP) was calculated.

Nitrogen load:

The Nitrogen Load risk level for contemporary (2000) conditions was very high. (level 5 of the five risk categories, where 1 = lowest risk; 5 = highest risk). Based on a “current trends” scenario (Global Orchestration), this remained the same in 2030 and 2050.

Nutrient ratio:

The Nutrient Ratio (ICEP) risk level for contemporary (2000) conditions was low (2). According to the Global Orchestration scenario, this increased to high in 2030 and remained high in 2050.

Merged nutrient indicator:

The risk level for the Merged Nutrient Indicator for contemporary (2000) conditions was very high (5). According to the Global Orchestration scenario, this remained the same in 2030 and 2050.

POPs:

This LME includes Vietnam and Southern China. Twelve samples at 11 locations are available. Average concentrations (ng.g^-1 of pellets) were high for DDT (176, range 1-558 ng.g^-1), moderate for PCBs (97, range 8-757 ng.g^-1), and minimal for HCHs (1.2, range 0.2-208 ng.g^-1). These averages correspond to risk categories 4, 3, and 1, respectively, of the five risk categories (1 = lowest risk; 5 = highest risk). High concentrations of DDTs were recorded both for northern Vietnam (163 – 558 ng.g^-1) and southern China including Hong Kong. Dominance of DDT over the degradation products (DDD and DDE) indicates current usage of DDT pesticide. DDT application for Malaria control could explain high DDTs concentrations in northern Vietnam and Haikou Bay (China), which have a tropical climate. Another possibility is illegal use of DDT pesticide for agricultural fields. In Hong Kong, the application of DDT to antifouling agents for boats is suspected. High DDTs concentrations were recorded even in the more recent samples. Source identification is highly recommended. Although the average PCBs concentration is moderate, the latest sample from Hong Kong showed an extremely high concentration (757 ng.g^-1), corresponding to risk category 5. This level may require regulatory and/or remediation action for food security.

Plastic debris:

Modelled estimates of floating plastic abundance (items km^-2), for both micro-plastic (<4.75 mm) and macro-plastic (>4.75 mm), indicate that this LME is in the group with the highest plastic concentration. Estimates are based on three proxy sources of litter: shipping density, coastal population density and the level of urbanisation within major watersheds, with enhanced run-off. The high values are due to relative importance of these sources in this LME. The abundance of floating plastic in this category is estimated to be on average over 400 times higher that those LMEs with lowest values. There is limited evidence from sea-based direct observations and towed nets to support this conclusion.

Ecosystem Health

Mangrove and coral cover:

0.2% of this LME is covered by mangroves (US Geological Survey, 2011) and 0.42% by coral reefs (Global Distribution of Coral Reefs, 2010).

Reefs at risk:

This LME has a present (2011) integrated threat index (combining threat from overfishing and destructive fishing, watershed-based and marine-based pollution and damage) of 241. 12% of coral reefs cover is under very high threat, and 17% under high threat (of the 5 possible threat categories, from low to critical). When combined with past thermal stress (between 1998 and 2007), these values increase to 19% and 24% for very high and high threat categories respectively. By year 2030, 26% of coral cover in this LME is predicted to be under very high to critical level of threat from warming and acidification; this proportion increases to 35% by 2050.

Marine Protected Area change:

The South China Sea LME experienced an increase in MPA coverage from 1,504 km² prior to 1983 to 91,480 km² by 2014. This represents an increase of 5,981%, within the medium category of MPA change.

Cumulative Human Impact:

The South China Sea LME experiences well above average overall cumulative human impact (score 4.42; maximum LME score 5.22). It falls in risk category 5 of the five risk categories (1 = lowest risk; 5 = highest risk). This LME is most vulnerable to climate change. Of the 19 individual stressors, all four connected to climate change have high average impact on the LME: ocean acidification (0.89; maximum in other LMEs was 1.20), UV radiation (0.51; maximum in other LMEs was 0.76), sea level rise (0.24; maximum in other LMEs was 0.71), and sea surface temperature (1.34; maximum in other LMEs was 2.16). Demersal destructive commercial fishing (0.34; maximum in other LMEs was 0.56) and demersal non-destructive high-bycatch (0.32; maximum in other LMEs was 0.60) also had high impact. Other key stressors include commercial shipping, ocean based pollution, and demersal non-destructive low-bycatch commercial fishing.

Ocean Health Index:

The South China Sea LME scores below average on the Ocean Health Index compared to other LMEs (score 63 out of 100; range for other LMEs was 57 to 82). This score indicates that the LME is well below its optimal level of ocean health, although there are some aspects that are doing well. Its score in 2013 increased 1 point compared to the previous year, due in large part to changes in the score for coastal economies. This LME scores lowest on food provision, coastal protection, carbon storage, tourism & recreation, sense of place and clean waters goals and highest on artisanal fishing opportunities. It falls in risk category 5 of the five risk categories, which is the highest level of risk (1 = lowest risk; 5 = highest risk).

Socio-economics

Indicators of demographic trends, economic dependence on ecosystem services, human wellbeing and vulnerability to present-day extreme climate events and projected sea level rise, are assessed for this LME. To compare and rank LMEs, they were classified into five categories of risk (from 1 to 5, corresponding to lowest, low, medium, high and highest risk, respectively) based on the values of the individual indicators. In the case of economic revenues, the LMEs were grouped to 5 classes of revenues from lowest, low, medium, high and highest, as revenues did not translate to risk.

Population:

The coastal area stretches over 765 002 km². A current population of 271 695 thousand in 2010 is projected to decrease to 213 297 thousand in 2100, with a density of 355 persons per km² in 2010 decreasing to 279 per km² by 2100. About 47% of coastal population lives in rural areas, and is projected to increase in share to 58% in 2100.

Coastal poor:

The indigent population makes up 14% of the LME’s coastal dwellers. This LME places in the low-risk category based on percentage and in the very high-risk category using absolute number of coastal poor (present day estimate).

Revenues and Spatial Wealth Distribution:

Fishing and tourism depend on ecosystem services provided by LMEs. This LME ranks in the very high-revenue category in fishing revenues based on yearly average total ex-vessel price of US 2013 $10 287 million for the period 2001-2010. Fish protein accounts for 28% of the total animal protein consumption of the coastal population. Its yearly average tourism revenue for 2004-2013 of US 2013 $234 946 million places it in the very high-revenue category. On average, LME-based tourism income contributes 12% to the national GDPs of the LME coastal states. Spatial distribution of economic activity (e.g. spatial wealth distribution) measured by night-light and population distribution as coarse proxies can range from 0.0000 (totally equal distribution and lowest risk) to 1.0000 (concentrated in 1 place and most inequitable and highest risk). The Night Light Development Index (NLDI) thus indicates the level of spatial economic development, and that for this LME falls in the category with high risk.

Human Development Index:

Using the Human Development Index (HDI) that integrates measures of health, education and income, the present-day LME HDI belongs to the medium HDI and medium-risk category. Based on an HDI of 0.700, this LME has an HDI Gap of 0.300, the difference between present and highest possible HDI (1.000). The HDI Gap measures an overall vulnerability to external events such as disease or extreme climate related events, due to less than perfect health, education, and income levels, and is independent of the harshness of and exposure to specific external shocks.
HDI values are projected to the year 2100 in the contexts of shared socioeconomic development pathways (SSPs). This LME is projected to assume a place in the very low risk category (very high HDI) in 2100 under a sustainable development pathway. Under a fragmented world scenario, the LME is estimated to place in a very high-risk category (very low HDI) because of reduced income levels and population values from those estimated in a sustainable development scenario.

Climate-Related Threat Indices:

The Climate-Related Threat Indices utilize the HDI Gaps for present-day and projected 2100 scenarios. The contemporary climate index accounts for deaths and property losses due to storms, flooding and extreme temperatures incurred by coastal states during a 20-year period from 1994 to 2013 as hazard measures, the 2010 coastal population as proxy for exposure, and the present day HDI Gap as vulnerability measure.
The Contemporary Threat Index incorporates a Dependence Factor based on the fish protein contribution to dietary animal protein, and on the mean contribution of LME tourism to the national GDPs of LME coastal states. The HDI Gap and the degree of dependence on LME ecosystem services define the vulnerability of a coastal population. It also includes the average of risk related to extreme climate events, and the risk based on the degrading system states of an LME (e.g. overexploited fisheries, pollution levels, decrease in coastal ecosystem areas).
The 2100 sea level rise threat indices, each computed for the sustainable world and fragmented world development pathways, use the maximum projected sea level rise at the highest level of warming of 8.5 W/m² in 2100 as hazard measure, development pathway-specific 2100 populations in the 10 m × 10 km coast as exposure metrics, and development pathway-specific 2100 HDI Gaps as vulnerability estimates.
Present day climate threat index of this LME is within the very high-risk (very high threat) category. The combined contemporaneous risk due to extreme climate events, degrading LME states and the level of vulnerability of the coastal population, is very high. In a sustainable development scenario, the risk index from sea level rise in 2100 is very low, and increases to high risk under a fragmented world development pathway.

Governance

Governance architecture:

This LME has two transboundary arrangements for fisheries (WCPFC and APFIC) where each cover high sea highly migratory tuna and tuna-like fisheries and the fisheries within national jurisdiction. There does not appear to be any formal connection between the two arrangements, possibly since they have different areas of competence. However, the arrangement for the Regional Seas Programme, the Coordinating Body of the Seas of South east Asia (COBSEA) covers both pollution and biodiversity , with linkages to the Partnership in Environmental Management for the Seas of East Asia (PEMSEA). However neither of these “within national jurisdiction” arrangements appears to be integrated with the other or with the tuna arrangement. Similarly, the specific biodiversity arrangement for turtles does not appear to be integrated with the other arrangements in the LME. No integrating mechanisms, such as an overall policy coordinating organization for the LME, could be found. There may be interaction amongst the arrangements through participation in each other’s meetings, but this appears to be informal.
The overall scores for ranking of risk were: