Aleutian Islands
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LME 65: Aleutian Islands

Bordering country:

United States of America

LME total area:

220,000 km²

LME overall risk:

This LME falls in the cluster of LMEs that exhibit high percentages of rural coastal population, high numbers of collapsed and overexploited fish stocks, as well as high proportions of catch from bottom impacting gear.
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 (0.800 mg.m^-3) in August and a minimum (0.259 mg.m^-3) during February. The average CHL is 0.507 mg.m^-3. Maximum primary productivity (230 g.C.m^-2.y^-1) occurred during 1999 and minimum primary productivity (127 g.C.m^-2.y^-1) during 2007. There is a statistically insignificant decreasing trend in Chlorophyll of -6.22 % from 2003 through 2013. The average primary productivity is 174 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 Aleutian Islands LME #65 has warmed by 0.40°C, thus being on a threshold between Categories 3 and 4 (moderate-to-slow warming LME). This newly-defined LME extends along the Aleutian Island chain, spanning both sides. It is affected by the Alaskan Stream on the Pacific side. It is also affected by the circulation within the Bering Sea. As a result, this LME is affected by currents of the subarctic North Pacific and, to a lesser extent, by water masses coming out of the Arctic Ocean through the Bering Sea past the Chukchi Peninsula (Chukotka). Two epochs can be identified separated by a step-like regime shift in 1976-1977. During the first, cooling epoch SST decreased from 6.2°C in 1957 down to <5.2°C. The regime shift of 1976-1977 manifested by an abrupt increase of SST from 5.2°C in 1976 to 6.2°C in 1977. The second, stable epoch commenced right after the regime shift of 1976-1977. This epoch has continued through 2012. During this stable preriod a warm peak of 6.6°C in 1996 stands out.

Fish and Fisheries

The Aleutian Islands LME supports around 37 species and the major targeted species is Arctic char (Salvelinus alpinus alpinus).

Annual catch:

Total reported landings rose steadily to a historic high of 0.3 million t in 1987, followed by a decline to around 0.15 million t in the recent years.

Catch value:

The value of the landings reached its peak at 0.3 billion US$ (in 2005 US$) in 1979.

Marine Trophic Index and Fishing-in-Balance index:

The MTI fluctuated around 4 from 1950 to the 2000s and then started to decline in the early 2000s. The FiB index kept decreasing from 1950 to 2010, which shows that there is no spatial expansion of fisheries in this region.

Stock status:

The Stock-Catch Status Plots indicate that about 45% of the commercially exploited stocks have collapsed and are over-exploited. The majority of the reported landings is still supplied by over-exploited stocks (i.e., 60% of the total catch).

Catch from bottom impacting gear:

The percentage of catch from the bottom gear type to the total catch reaches its first maximum at 16% in 1965 and then this percentage dropped to 5 % in 1983. It fluctuated between 7 to 14% in the last 20 years.

Fishing effort:

The total effective effort fluctuated between 3 and 5 million kW from 1950 to 1980 and started to increase since the 1980s. It keeps increasing continuously in the last few decades and reaches its maximum in 2001 at 12 million kW.

Primary Production Required:

The primary production required (PPR) to sustain the reported landings in this LME is less than 1% in these 60 years.

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:

No data for this LME

Nutrient ratio:

No data for this LME

Merged nutrient indicator:

No data for this LME

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 the lowest 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 low values are due to the remoteness of this LME from significant sources of plastic. The abundance of floating plastic in this category is estimated to be over 400 times lower than those LMEs with the highest values. There is limited evidence from sea-based direct observations and towed nets to support this conclusion.

Ecosystem Health

Mangrove and coral cover:

Not applicable

Reefs at risk:

Not applicable

Marine Protected Area change:

The Aleutian Islands LME experienced an increase in MPA coverage from 1,313 km² prior to 1983 to 3,670 km² by 2014. This represents an increase of 180%, within the low category of MPA change.

Cumulative Human Impact:

The Aleutian Islands LME experiences average overall cumulative human impact (score 3.05; maximum LME score 5.22), but which is still well above the LME with the least cumulative impact. It falls in risk category 2 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 (0.64; maximum in other LMEs was 1.20), UV radiation (0.60; maximum in other LMEs was 0.76), and sea surface temperature (1.29; maximum in other LMEs was 2.16). Other key stressors include commercial shipping, ocean based pollution, and demersal destructive commercial fishing.

Ocean Health Index:

The Aleutian Islands LME scores above average on the Ocean Health Index compared to other LMEs (score 72 out of 100; range for other LMEs was 57 to 82), but still relatively low. 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 9 points compared to the previous year, due in large part to changes in the score for clean waters. This LME scores lowest on food provision, coastal livelihoods and tourism & recreation goals and highest on artisanal fishing opportunities, coastal economies, and lasting special places goals. It falls in risk category 2 of the five risk categories, which is a moderate 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 460 km². A current population of 287 in 2010 is projected to increase to 4 466 in 2100, with a density of 6 persons per 10 km² in 2010 increasing to 97 per 10 km² by 2100. About 100% of coastal population lives in rural areas, and is projected to remain the same in 2100.

Coastal poor:

The indigent population makes up 17% of the LME’s coastal dwellers. This LME places in the high-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 7% of the total animal protein consumption of the coastal population. Its yearly average tourism revenue for 2004-2013 of US 2013 $36 million places it in the very low revenue category. On average, LME-based tourism income contributes 8% 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, this LME HDI belongs to the very high HDI and very low risk category. Based on an HDI of 0.909, this LME has an HDI Gap of 0.091, 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 maintain its position in the very low risk category (highest HDI) in 2100 under a sustainable development pathway or scenario. Under a fragmented world scenario, this LME is projected to slip to the high-risk category (low HDI) because of reduced income level and bigger population size compared to 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 to 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. Regardless of development pathway, this LME is projected to belong to the very low risk category that is least threatened by sea level rise in 2100.