Kuroshio Current
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LME 49: Kuroshio Current

Bordering countries:

Japan, Philippines, Taiwan

LME total area:

1,333,074 km²

LME overall risk:

This LME falls in the cluster of LMEs that exhibit medium to high numbers of collapsed and overexploited fish stocks, high levels of demersal non-destructive low bycatch fishing, as well as very high shipping pressure.
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 medium.

Productivity

Chlorophyll-A:

The annual Chlorophyll a concentration (CHL) cycle has a maximum peak (0.253 mg.m^-3) in April and a minimum (0.0989 mg.m^-3) during August. The average CHL is 0.157 mg.m^-3. Maximum primary productivity (186 g.C.m^-2.y^-1) occurred during 1999 and minimum primary productivity (137 g.C.m^-2.y^-1) during 2012. There is a statistically insignificant decreasing trend in Chlorophyll of -8.96 % from 2003 through 2013. The average primary productivity is 156 g.C.m^-2.y^-1, which places this LME in Group 2 of 5 categories (with 1 = lowest and 5= highest).

Primary productivity:

Sea Surface Temperature:

From 1957 to 2012, the Kuroshio Current LME #49 has warmed by 0.70°C, thus belonging to Category 3 (moderate warming LME). The thermal history of this LME is similar to that of the East China Sea. Both saw a relatively stable epoch in the 1960s-1970s, and a rapid warming in the 1980s-1990s culminated (and terminated) by the 1998 El-Niño. The main difference is that in the Kuroshio Current the stable epoch lasted longer, through 1986. The rather sharp decline of SST after the 1998 El Niño was also quite similar in the Kuroshio and East China Sea, and also in the Taiwan Strait (Belkin, 2009; Belkin and Lee, 2014). The thermal regime of the Kuroshio LME exerts a profound impact on (1) the Taiwan Strait via the Luzon Strait and South China Sea, and (2) the East China Sea via the Kuroshio incursions onto the outer East China Sea shelf (Belkin and Lee, 2014).

Fish and Fisheries

Annual catch:

Total reported landings in this LME reached 1.5 million t in late 1980s, but has been on a decline following the collapse of the sardine fisheries which dominated the landings in the 1980s.

Catch value:

The value of the reported landing recorded a peak of nearly 3 billion US$ (in 2005 real US$) in 1995 but has declined along with the reduced landings.

Marine Trophic Index and Fishing-in-Balance index:

The MTI shows a series of large fluctuations, reflecting the cyclic nature in the relative abundance, and hence the landings of Pacific sardine in the LME. The FiB index declined from mid 1960s to 1980s, indicating that a “fishing down” of the food webs in the LME. After late 1980s, the FiB index continued to increase until late 1990s, indicating the geographical expansion of the fisheries.

Stock status:

The Stock-Catch Status Plots indicate that the number of collapsed and overexploited stock has been on a rise, accounting for 55% of the commercially exploited stocks by 2010, with more than half of the reported landings supplied by overexploited stocks. This is in line with the landings trends, which are declining since the mid-1980s.

Catch from bottom impacting gear:

The percentage of catch from the bottom gear type to the total catch decreased from around 18% in the 1950s to its lowest point at around 5% in 1987. Then, this percentage kept increasing and fluctuated around 28% in recent decade.

Fishing effort:

The total effective effort continuously increased from around 36 million kW in the 1950s to its peak around 215 million kW in 2005.

Primary Production Required:

The primary production required (PPR) to sustain the reported landings in the LME reached 70% of the observed primary production in the late 1990s. Two likely explanations for the extremely high level of PPR recorded in the 1980s and 1990s are the over-reporting in the underlying landings statistics by China and the shift in the distribution of Pacific sardine beyond the LME boundary which may have resulted in misreporting of some of sardine landings as being caught within the LME.

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 moderate (level 3 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 remained the same in 2030 and decreased to very low in 2050.

Merged nutrient indicator:

The risk level for the Merged Nutrient Indicator for contemporary (2000) conditions was moderate (3). According to the Global Orchestration scenario, this remained the same in 2030 and 2050.

POPs:

Data are available from 6 samples from 4 locations in Tokyo Bay. All the samples show high to extremely high PCBs concentrations (average 474, range 259-653 ng.g^-1 of pellets), moderate concentrations for DDTs (average 50, range 21-79 ng.g^-1), and minimal concentrations (1.6, range 1.2-2.1 ng.g^-1) for HCHs. PCBs and DDTs averages correspond to risk categories 4 and 3, respectively, of the five risk categories (1 = lowest risk; 5 = highest risk). Both PCBs and DDTs are derived from legacy pollution source in the bottom sediment. PCB concentration was more than 500 ng.g^-1, corresponding to risk category 5, even in the recent samples collected from the inner head of the bay. Some remediation action (e.g., dredging, capping) is necessary if the consumption of seafood from the area is allowed. Comprehensive monitoring including in some other coasts in this LME is highly recommended to ensure that the pollution status was not overestimated.

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:

0.0008% of this LME is covered by mangroves (US Geological Survey, 2011) and 0.12% 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 289. 26% of coral reefs cover is under very high threat, and 37% 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 59% and 30% for very high and high threat categories respectively. By year 2030, 42% 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 64% by 2050.

Marine Protected Area change:

The Kuroshio Current LME experienced an increase in MPA coverage from 2,339 km² prior to 1983 to 14,719 km² by 2014. This represents an increase of 529%, within the low category of MPA change.

Cumulative Human Impact:

The Kuroshio Current LME experiences well above average overall cumulative human impact (score 4.32; 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, three connected to climate change have the highest average impact on the LME: ocean acidification (1.10; maximum in other LMEs was 1.20), UV radiation (0.63; maximum in other LMEs was 0.76), and sea surface temperature (1.53; maximum in other LMEs was 2.16). Other key stressors include commercial shipping, ocean based pollution, invasive species, and all three types of demersal commercial fishing (demersal destructive, non-destructive low-bycatch, and non-destructive high-bycatch).

Ocean Health Index:

The Kuroshio Current LME scores below average on the Ocean Health Index compared to other LMEs (score 69 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 remained unchanged compared to the previous year. This LME scores lowest on food provision, natural products, tourism & recreation, and iconic species goals and highest on artisanal fishing opportunities, coastal protection, carbon storage, coastal economies, lasting special places, and habitat biodiversity goals. It falls in risk category 3 of the five risk categories, which is an average 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 260,980 km². A current population of 111 318 thousand in 2010 is projected to decrease to 91 035 thousand in 2100, with a density of 426 persons per km² in 2010 decreasing to 349 per km² by 2100. About 17% of coastal population lives in rural areas, and is projected to decrease in share to 16% in 2100.

Coastal poor:

The indigent population makes up 15% of the LME’s coastal dwellers. This LME places in the medium-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 high-revenue category in fishing revenues based on yearly average total ex-vessel price of US 2013 $1 617 million for the period 2001-2010. Fish protein accounts for 36% of the total animal protein consumption of the coastal population. Its yearly average tourism revenue for 2004-2013 of US 2013 $102 053 million places it in the very high-revenue category. On average, LME-based tourism income contributes 7% 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 low 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 very high HDI and very low-risk category. Based on an HDI of 0.887, this LME has an HDI Gap of 0.113, 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 medium-risk category (medium HDI) because of reduced income levels and population values from those in a sustainable development pathway.

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 low-risk (low threat) category. The combined contemporaneous risk due to extreme climate events, degrading LME states and the level of vulnerability of the coastal population, is medium. In a sustainable development scenario, the risk index from sea level rise in 2100 is very low, and increases to medium under a fragmented world development pathway.

Governance

Governance architecture:

In this LME, there is essentially no transboundary fisheries arrangement. However, PICES does provide opportunity for transboundary cooperation in assessment in science. The fact that there is no Regional Seas convention covering the area in this LME, but only an action plan (NOWPAP), seriously weakens capacity for transboundary governance in areas relating to pollution. Further, there is no indication of transboundary integration, other than through cooperation in science. There is the potential for integration of pollution issues under NOWPAP should it proceed to the level of a Convention. There does not appear to be any other transboundary organisation than NOWPAP that could integrate and coordinate across the full range of issues required for EBM.
The overall scores for ranking of risk were: