Arabian Sea
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LME 32: Arabian Sea

Bordering countries:

Bahrain, Djibouti, India, Iran, Iraq, Kuwait, Oman, Pakistan, Qatar, Saudi Arabia, Somalia, United Arab Emirates, Yemen

LME total area:

3,950,421 km²

LME overall risk:

This LME falls in the cluster of LMEs that exhibit low to medium levels of economic development (based on the night light development index) and medium levels of collapsed and overexploited fish stocks.
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 (0.674 mg.m^-3) in August and a minimum (0.176 mg.m^-3) during May. The average CHL is 0.368 mg.m^-3. Maximum primary productivity (531 g.C.m^-2.y^-1) occurred during 1999 and minimum primary productivity (379 g.C.m^-2.y^-1) during 2011. There is a statistically insignificant decreasing trend in Chlorophyll of -18.2 % from 2003 through 2013. The average primary productivity is 450 g.C.m^-2.y^-1, which places this LME in Group 5 of 5 categories (with 1 = lowest and 5= highest).

Primary productivity:

Sea Surface Temperature:

From 1957 to 2012, the Arabian Sea LME #32 has warmed by 0.48°C, thus belonging to Category 3 (moderate warming LME). Like all Indian Ocean LMEs, the Arabian Sea warmed slowly and steadily, except for a sharp drop below 27°C in 1975. Interannual variability of SST in this LME is relative small, with a magnitude of ~0.5°C. The most pronounced event, the all-time minimum of 1975, was likely caused by large-scale forcing since it occurred simultaneously across the entire northern Indian Ocean, including the Red Sea LME #33 and the Bay of Bengal LME #34. The near-all-time maximum of 1998 occurred simultaneously with most Indian Ocean LMEs and only one year before a near-all-time maximum of 1999 in the Red Sea. The rapid warming between 1985 and 1987 ushered in the modern warm epoch in the Arabian Sea. This warming occurred nearly synchronously with a similar warming in the Somali Coastal Current LME #31.

Fish and Fisheries

The fisheries of the Arabian Sea LME are multi-gear and multi-species and include both artisanal and commercial sectors, with the former being dominant. Among the major exploited groups are Indian oil sardine (Sardinella longiceps), caught mainly off India’s west coast. However, nearly half of the reported landings in the LME are identified only as ‘marine fish’.

Annual catch:

Total reported landings increased steadily, reaching 3.3 million t in 2006.

Catch value:

The value of the reported landings reached around 5.5 billion US$ (in 2005 value) in 1992.

Marine Trophic Index and Fishing-in-Balance index:

From the early 1980s to the late 1990s, both the MTI and the FiB index showed an increase, consistent with a spatial (offshore) expansion of fisheries targeting high trophic level large pelagic fishes in the region. However, MTI computed without the landings of tuna and other large pelagic species shows a steady decline since 1975, suggesting the occurrence of a strong ‘fishing down’ effect.

Stock status:

The Stock-Catch Status Plots indicate that the number of collapsed and overexploited stocks in the LME have been rapidly increasing, to more than 30% in recent years, but that over 80 % of the catch is still taken from fully exploited stocks.

Catch from bottom impacting gear:

The percentage of catch from the bottom gear type to the total catch increased from 30% in the 1950s to its first peak at around 40% in 1971. Then, this percentage kept decreasing and fluctuated around 17% in recent decade.

Fishing effort:

The total effective effort continuously increased from around 20 million kW in 1950 to its peak around 430 million kW in the mid-2000s.

Primary Production Required:

The primary production required (PPR) to sustain the reported landings in this LME reached 20% of the observed primary production in the mid-1990s, but has since declined.

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 moderate (3). According to the Global Orchestration scenario, this remained the same in 2030 and increased to high 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 increased to high in 2050.

POPs:

Data are available for only one sample at one location in Mumbai, India. This location shows moderate concentration for PCBs (53 ng.g^-1 of pellets), corresponding to risk category 3, and low concentration for DDTs (10 ng.g^-1) and minimal concentration for HCHs (1.8 ng.g^-1), corresponding to risk category 2 of the five risk categories (1 = lowest risk; 5 = highest risk). Moderate concentration of PCBs could be derived from old electronic instruments. Due to the rapid economic growth and associated pollution concerns, extensive monitoring is necessary in this LME.

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 relatively high levels of 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 the relative importance of these sources in this LME. The abundance of floating plastic in this category is estimated to be on average over 100 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:

0.03% of this LME is covered by mangroves (US Geological Survey, 2011) and 0.1% by coral reefs ().

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 231. 22% of coral reefs cover is under very high threat, and 15% 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 24% and 25% for very high and high threat categories respectively. By year 2030, 23% 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 37% by 2050.

Marine Protected Area change:

The Arabian Sea LME experienced an increase in MPA coverage from 2,071 km² prior to 1983 to 12,449 km² by 2014. This represents an increase of 501%, within the low category of MPA change.

Cumulative Human Impact:

The Arabian Sea LME experiences an above average overall cumulative human impact (score 4.12; maximum LME score 5.22), which is also well above the LME with the least cumulative impact. It falls in risk category 4 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 (1.00; maximum in other LMEs was 1.20), UV radiation (0.61; maximum in other LMEs was 0.76), and sea surface temperature (1.65; maximum in other LMEs was 2.16). Other key stressors include commercial shipping, sea level rise, ocean based pollution, demersal destructive commercial fishing, and demersal non-destructive low-bycatch commercial fishing.

Ocean Health Index:

The Arabian Sea LME scores below average on the Ocean Health Index compared to other LMEs (score 66 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 mariculture, coastal protection, tourism & recreation, and sense of place goals and highest on artisanal fishing opportunities and coastal economies goals. 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 513 873 km². A current population of 27 950 thousand in 2010 is projected to increase to 108 998 thousand in 2100, with a density of 54 persons per km² in 2010 reaching 202 per km² by 2100. About 58% of coastal population lives in rural areas, and is projected to increase in share to 68% in 2100.

Coastal poor:

The indigent population makes up 24% of the LME’s coastal dwellers. This LME places in the very high-risk category based on percentage and in the 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 low-revenue category in fishing revenues based on yearly average total ex-vessel price of US 2013 $230 million for the period 2001-2010. Fish protein accounts for 9% of the total animal protein consumption of the coastal population. Its yearly average tourism revenue for 2004-2013 of US 2013 $12 134 million places it in the low-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 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 low HDI and high-risk category. Based on an HDI of 0.648, this LME has an HDI Gap of 0.352, 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 increased 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 high-risk (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 high. In a sustainable development scenario, the risk index from sea level rise in 2100 is very low, and increases to very high risk under a fragmented world development pathway.

Governance

Governance architecture:

While this LME has two separate regional seas agreements (in place covering pollution (LBS and MBS) and biodiversity (Kuwait and Jeddah Conventions and protocols), no overarching integrating mechanisms, such as an overall policy coordinating organisation 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. In terms of transboundary fisheries arrangements, these are also not formally integrated although informal linkages may be present at some level.
The overall scores for ranking of risk were: