Gulf of Alaska
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LME 2: Gulf of Alaska

Bordering countries:

United States of America, Canada

LME total area:

1,491,252 km²

LME overall risk:

This LME falls in the cluster of LMEs that exhibit medium numbers of collapsed and overexploited fish stocks, as well as very 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 low.

Productivity

Chlorophyll-A:

The annual Chlorophyll a concentration (CHL) cycle has a maximum peak (0.695 mg.m^-3) in May and a minimum (0.280 mg.m^-3) during December. The average CHL is 0.534 mg.m^-3. Maximum primary productivity (267 g.C.m^-2.y^-1) occurred during 1999 and minimum primary productivity (198 g.C.m^-2.y^-1) during 2011. There is a statistically insignificant increasing trend in Chlorophyll of 19.5 % from 2003 through 2013. The average primary productivity is 221 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:

Between 1957 and 2012, the Gulf of Alaska (GOA) LME #2 has warmed by 0.06°C. It thus belongs to Category 4 (slow-warming LME). During 1957-2012 four epochs can be distinguished: (1) rapid cooling by nearly 2°C after the sharp peak of 1958; (2) cold spell, 1971-1976; (3) warming epoch, 1977-1997; (4) cooling epoch, 1998-2012. The transition from the cold spell to the warming epoch has occurred in one year, during the North Pacific regime shift of 1976-1977 (Hare and Mantua, 2000). In general, the SST history of the GOA is very similar to that of the East Bering Sea LME #01. In particular, the SST swings in 1996-2012 were synchronous: from the peaks in 1997-1998 (linked to El-Niño), followed by a 1°C drop by 1999, to another maximum in 2003-2005, followed by another drop in 2008.

Fish and Fisheries

This LME supports a number of commercially important fisheries including crab, shrimp, pollock, Pacific cod, mackerel, sockeye salmon, pink salmon and halibut. Also caught are king crab, tanner crab, and shrimp.

Annual catch:

Total reported landings in this LME showed increases in the early 1960s and in the mid-1980s, both linked to the increase in the Alaska pollock landings, and recorded a peak landing of 1.4 million t in 1989.

Catch value:

The value of the reported landings recorded a peak of 1.4 billion US$ (in 2005 real US$) in 1979, and reached its second peak of 1.3 billion US$ (in 2005 real US$) in 1988 but has since declined to 580 million US$ (in 2005 real US$) in recent years.

Marine Trophic Index and Fishing-in-Balance index:

The MTI has remained fairly stable over the reported period, due to the relative abundance of Alaska pollock in the landings. The increase in the FiB index in the early 1980s reflects the increased landings reported during that period.

Stock status:

The Stock-Catch Status Plots indicate that about 40% of the commercially exploited stocks have either collapsed or are overexploited. The majority of the reported landings is supplied by fully exploited and overexploited stocks, or more specifically, by Alaska pollock.

Catch from bottom impacting gear:

The percentage of catch from the bottom gear type to the total catch reaches its maximum at 48% in 1965 and then this percentage ranges between 12 to 18% in the recent few decades.

Fishing effort:

The total effective effort increased from around 90 million kW in the 1970s to its peak at 300 million kW in 1993. It then fluctuated between 200 and 300 million kW in the recent decade.

Primary Production Required:

The primary production required (PPR) to sustain the reported landings in this LME reached 30% of the observed primary production in the late 1980s and has leveled at around 25% in recent 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:

The Nitrogen Load risk level for contemporary (2000) conditions was low (level 2 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 very low (1). 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 low (2). According to the Global Orchestration scenario, this remained the same in 2030 and 2050.

POPs:

Data are available for only one sample at a rural location in Washington State (USA). The location shows a concentration (ng.g^-1 of pellets) of 30 ng.g^-1 for PCBs, 5 ng.g^-1 for DDTs, and 0.3 ng.g^-1 for HCHs. These correspond to risk category 2 for PCBs, 2 for DDTs, and 1 for HCHs, of the five risk categories (1 = lowest risk; 5 = highest risk). This is probably due to minimal anthropogenic activities involving the use of POPs (PCBs in industries and DDT and HCH pesticides in agriculture). More samples and locations are necessary to properly evaluate 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 Gulf of Alaska LME experienced an increase in MPA coverage from 8,082 km² prior to 1983 to 85,277 km² by 2014. This represents an increase of 955%, within the low category of MPA change.

Cumulative Human Impact:

The Gulf of Alaska LME experiences an average overall cumulative human impact (score 2.91; maximum LME score 5.22), but which is still well above the LME with the least cumulative impact. It falls in risk category 1 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 (0.80; maximum in other LMEs was 1.20), UV radiation (0.7; maximum in other LMEs was 0.76), and sea surface temperature (0.78; 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 Gulf of Alaska 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 7 points compared to the previous year, due in large part to changes in the scores for clean waters. This LME scores lowest on food provision, natural products, and tourism & recreation goals and highest on artisanal fishing opportunities, coastal protection, coastal economies, and species diversity 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 the Gulf of Alaska 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:

This LME’s coastal area includes the southern shoreline of the Alaskan Peninsula and Canada’s west coast. It is moderately large in population size and is among the most urbanized LMEs with 7% and 11% living in rural areas in 2010 and 2100, respectively. It covers 634,046 km², with a density of 13 people per km² in 2010 and increasing to 15 per km² in 2100.

Coastal poor:

The indigent population makes up 15% of the LME’s coastal dwellers. This LME places in the moderate risk category based on percentage and absolute number of poor at nearly 1.3 million (present day estimate).

Revenues and Spatial Wealth Distribution:

Fishing and tourism depend on ecosystem services provided by LMEs. The Gulf of Alaska LME ranks in the moderately high revenue category in fishing revenues based on yearly average total ex-vessel price of almost US 2013 $634 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 close to US 2013 $15 billion (thousand million) places it in the moderately high revenue category as well. On average, LME-based tourism income contributes 6% 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 the Gulf of Alaska LME falls in the category with lowest risk.

Human Development Index:

Using the Human Development Index (HDI) that integrates measures of health, education and income, the present-day Gulf of Alaska LME HDI belongs to the highest HDI and lowest risk category. Based on an HDI of 0.905, this LME has an HDI Gap of 0.095, 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). The Gulf of Alaska LME is projected to maintain its position in the lowest 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 moderate risk category (moderately high HDI) because of reduced income level and bigger population size compared to estimated income and population values 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 to the Gulf of Alaska 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 low. Under a sustainable development scenario, this LME is projected to belong to the lowest risk category that is least threatened by sea level rise in 2100. In a fragmented world development pathway, this LME goes up to the low risk category because of a wider HDI Gap generated by a bigger population and reduced income, with the same hazard level.