Northwest Australian Shelf
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LME 45: Northwest Australian Shelf

Bordering country:

Australia

LME total area:

911,812 km²

LME overall risk:

This LME falls in the cluster of LMEs that exhibit high rates of increase in MPA coverage.
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 low.

Productivity

Chlorophyll-A:

The annual Chlorophyll a concentration (CHL) cycle has a maximum peak (0.246 mg.m^-3) in July and a minimum (0.112 mg.m^-3) during December. The average CHL is 0.154 mg.m^-3. Maximum primary productivity (262 g.C.m^-2.y^-1) occurred during 2004 and minimum primary productivity (212 g.C.m^-2.y^-1) during 2013. There is a statistically insignificant decreasing trend in Chlorophyll of -15.6 % from 2003 through 2013. The average primary productivity is 233 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 Northwest Australian Shelf LME #45 has warmed by 0.50°C, thus belonging to Category 3 (moderate warming LME). The interannual variability of SST in this LME is rather small, with year-to-year variations of SST being <0.5°C. The only significant warm event, the all-time maximum of SST>28.2°C in 1998, was caused by the El Niño 1997-98. The most significant cold event has bottomed out at <26.7°C in 1976, when SST anomaly was about -1°C relative to the long-term trend. This event can be associated with the cold event of 1976-77 in the North Australian Shelf LME #39. This is a rare example of a large signal confined to just two contiguous LMEs that comprise a relatively small area. Another cold signal, of 1968, likely travelled from the Indonesian Sea LME #38, where a cold event occurred in 1967. The proposed travel route is consistent with the regional circulation pattern.

Fish and Fisheries

Northwest Australian waters are relatively nutrient-poor and unable to sustain large fish populations. The level of endemism in the LMEs is low, with most species distributed widely in the Indo-West Pacific region. Demersal species fished in this LME include Lethrinus, Nemipterus, Saurida and Lutjanus, which have historically been fished by foreign fleets. Other exploited groups include Anadara clams, scallops and goldstripe sardinella, as well as a significant number of unidentified taxa.

Annual catch:

Total reported landings show a series of peaks in the 1990s over 50,000 t with a record landing of 60,000 t in 2005.

Catch value:

From the early 1990s to 2005, the value of the catch increased sharply and then fluctuated between 185 and 195 million US$ (in 2005 real US$) in the recent 5 years.

Marine Trophic Index and Fishing-in-Balance index:

Since the mid-1980s, both the MTI and the FiB index showed an increase, likely a result of geographic expansion of the fisheries and targeting of large and medium pelagic species.

Stock status:

The Stock-Catch Status Plots indicate that approximately 35% of the stocks have collapsed or are overexploited in the LME. The reported landings are largely generated by fully exploited and developing stocks.

Catch from bottom impacting gear:

The percentage of catch from the bottom gear type to the total catch fluctuated between 7 and 43% from 1950 to 2010. This percentage fluctuated around 25% in the recent decade.

Fishing effort:

The total effective effort continuously fluctuated between 0.6% and 3.6% from 1950 to 1991 and then it increased to its first peak at 15 million kW in 1993.

Primary Production Required:

The primary production required (PPR) to sustain the reported landings in this LME has reached 2.5% in the 1990s, which is very low.

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 low. (level 1 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 2050.

Merged nutrient indicator:

The risk level for the Merged Nutrient Indicator for contemporary (2000) conditions was very low (1). According to the Global Orchestration scenario, this remained the same in 2030 and 2050.

POPs:

No pellet samples were obtained from 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 moderate 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 12 times lower 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:

0.16% of this LME is covered by mangroves (US Geological Survey, 2011) and 0.31% 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 118. 0.52% of coral reefs cover is under high threat, and 17% under medium 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 0.52% and 14% for very high and high threat categories respectively. By year 2030, 0% of coral cover in this LME is predicted to be under very high to critical level of threat from warming and acidification, with 13% under high threat; this proportion increases to 0.52% under very high and 16% under high threat by 2050.

Marine Protected Area change:

The Northwest Australian Shelf LME experienced an increase in MPA coverage from 0 km² prior to 1983 to 269,117 km² by 2014. This represents an increase of 50,000%, within the highest category of MPA change.

Cumulative Human Impact:

The Northwest Australian Shelf LME experiences above average overall cumulative human impact (score 3.68; maximum LME score 5.22), which is also well above the LME with the least cumulative impact. It falls in risk category 3 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 the highest average impact on the LME: ocean acidification (0.93; maximum in other LMEs was 1.20), UV radiation (0.55; maximum in other LMEs was 0.76), sea level rise (0.23; maximum in other LMEs was 0.71), and sea surface temperature (1.49; maximum in other LMEs was 2.16). Other key stressors include commercial shipping, ocean based pollution, pelagic high-bycatch commercial fishing, and demersal destructive and non-destructive high-bycatch commercial fishing.

Ocean Health Index:

The NorthWest Australian Shelf LME scores above average on the Ocean Health Index compared to other LMEs (score 79 out of 100; range for other LMEs was 57 to 82 but still relatively low. This score indicates that the LME is 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 scores for natural products and coastal livelihoods. This LME scores lowest on food provision and coastal protection goals and highest on artisanal fishing opportunities, carbon storage, coastal livelihoods & economies, clean water and habitat biodiversity goals. It falls in risk category 1 of the five risk categories, which is the lowest 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 213,798 km². A current population of 61 thousand in 2010 is projected to decrease to 13 thousand in 2100, with a density of 29 persons per 100 km² in 2010 decreasing to 6 per 100 km² by 2100. About 79% of coastal population lives in rural areas, and is projected to slightly decrease in share to 78% in 2100.

Coastal poor:

The indigent population makes up 14% of the LME’s coastal dwellers. This LME places in the medium-risk category based on percentage and in the very low-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 $200 million for the period 2001-2010. Fish protein accounts for 8% of the total animal protein consumption of the coastal population. Its yearly average tourism revenue for 2004-2013 of US 2013 $15 953 million places it in the medium-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 very 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 0.942, this LME has an HDI Gap of 0.058, 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 very low-risk (very 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 very low. In a sustainable development scenario, the risk index from sea level rise in 2100 is very low, and maintains this even under a fragmented world development pathway.