Northeast U.S. Continental Shelf
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LME 7: Northeast U.S. Continental Shelf

Bordering countries:

United States of America, Canada

LME total area:

308,554 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 low.

Productivity

Chlorophyll-A:

The annual Chlorophyll a concentration (CHL) cycle has a maximum peak (1.51 mg.m^-3) in April and a minimum (0.866 mg.m^-3) during August. The average CHL is 1.02 mg.m^-3. Maximum primary productivity (402 g.C.m^-2.y^-1) occurred during 2000 and minimum primary productivity (327 g.C.m^-2.y^-1) during 2004. There is a statistically insignificant increasing trend in Chlorophyll of 7.75 % from 2003 through 2013. The average primary productivity is 365 g.C.m^-2.y^-1, which places this LME in Group 4 of 5 categories (with 1 = lowest and 5= highest).

Primary productivity:

Sea Surface Temperature:

Between 1957 and 2012, the Northeast U.S. Continental Shelf LME #07 has warmed by 1.40°C, thus belonging to Category 1 (super-fast warming LME). The cold spell in the 1960s resulted in a 2°C SST drop down to 10.9°C by 1965; a recovery took four years. This cold event profoundly affected the Northeast U.S. Shelf ecosystem. For example, winter flounder thrived during the cold spell, whereas stocks of other species less tolerant to the cold, dwindled. After 1965, the Northeast U.S. Continental Shelf experienced a steady long-term warming, from 10.9°C in 1965 up to 14.6°C in 2012, hence a 3.7°C warming in 47 years, making the Northeast U.S. Continental Shelf one of the fastest warming LMEs. The most recent rapid warming (since 2007) is especially notable. The thermal history of the Northeast U.S. Continental Shelf LME #07 is dramatically different from that of the adjacent Southeast U.S. Continental Shelf LME #06. This can be explained by cardinal differences in oceanographic settings of these ecosystems.

Fish and Fisheries

The catch composition of this LME is diverse. In the late 1960s and early 1970s, there was intense foreign fishing within the LME. The precipitous decline in biomass of fish stocks during this period was the result of excessive fishing mortality.

Annual catch:

Total reported landings declined from more than 1.8 million t in 1973 to less than 800,000 t from 1998 to 2000, and then fluctuated between 740,000 and 1 million t in the past 10 years.

Catch value:

The value of the reported landings reached 6.5 billion US$ (in 2005 real US$) in 1979, and fluctuated between 2.5 and 4.4 billion US$ in the recent decade (2001 – 2010).

Marine Trophic Index and Fishing-in-Balance index:

The MTI declined since the early 1960s, when demersal fish in the LME came under strong exploitation, which is a clear case of ‘fishing down’ of the food web. The FiB index showed a similar decline, implying that the increase in the reported landings recorded in the 1970s did not compensate for the decline in the MTI over that period.

Stock status:

The Stock-Catch Status Plots shows that about 50% of commercially exploited stocks in the LME have collapsed, with another 20% being overexploited. Slightly over 50% of the reported landings biomass is supplied by these two stock categories.

Catch from bottom impacting gear:

The percentage of catch from the bottom gear type to the total catch reaches its maximum at 63% in 1965 and then this percentage ranges between 45 to 60% in the recent few decades.

Fishing effort:

The total effective effort increased steadily from around 9 million kW in the 1950s to its peak at 380 million kW in 2006.

Primary Production Required:

The primary production required (PPR) to sustain the reported landings in the LME reached 90 % of the observed primary production in the mid-1960s, but has declined to less than 20 % in recent years. The extremely high PPR recorded in the 1960s and 1970s was likely due to the exploitation of the accumulated biomass of cod and other stocks rather than from exploitation of annual surplus production in 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 moderate (3). According to the Global Orchestration scenario, this increased to high in 2030 and decreased back to moderate 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 increased to high in 2030 and then decreased to moderate in 2050.

POPs:

The Northeast U.S. Continental Shelf LME has 3 samples at 3 locations. The average concentration (ng.g^-1 of pellets) was 275 (range 92-405 ng.g^-1) for PCBs, 20 (range 7-47 ng.g^-1) for DDTs, and 1.6 (range 0.04 -4.3 ng.g^-1) for HCHs. The PCBs, DDTs and HCHs averages correspond to risk category 4, category 3, and category 1, respectively, of the 5 risk categories (1 = lowest risk; 5 = highest risk). Higher concentrations of PCBs (405 ng.g^-1 in Boston Harbor; 328 ng.g^-1 in New Jersey) were probably due to proximity to the urban centers such as Boston and New York, and are ascribed to legacy pollution. For comprehensive evaluation of this LME, collection and analysis of pellets from suburban and rural areas in addition to more locations in urban areas are necessary.

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 good 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 Northeast U.S. Continental Shelf LME experienced an increase in MPA coverage from 1,366 km² prior to 1983 to 38,729 km² by 2014. This represents an increase of 2,734%, within the medium category of MPA change.

Cumulative Human Impact:

The Northeast US Continental Shelf LME experiences an above average overall cumulative human impact (score 3.73; maximum LME score 5.22), which is 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: sea surface temperature (1.13; maximum in other LMEs was 2.16), ocean acidification (0.52; maximum in other LMEs was 1.20), UV radiation (0.47; maximum in other LMEs was 0.76), and sea level rise (0.31; maximum in other LMEs was 0.71). Other key stressors include commercial shipping, ocean based pollution, and all three types of demersal commercial fishing (destructive, non-destructive low-bycatch, and non-destructive high-bycatch).

Ocean Health Index:

The Northeast US Continental Shelf 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 8 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, carbon storage, coastal livelihoods, tourism & recreation, and iconic species goals and highest on artisanal fishing opportunities, coastal economies, lasting special places, 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 Northeast U.S. Continental Shelf 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 includes the northeastern seaboard of the United States of America and the western shore of the Bay of Fundy in Canada, and stretches over 264,996 km². Its current population of 60 million is projected to increase by 13.6 million in 2100, and a density increasing from 227 persons per km² in 2010 to 278 per km² by 2100. About 9% of coastal population lives in rural areas, and is projected to decrease to 12% in 2100.

Coastal poor:

The indigent population makes up 17% of the LME’s coastal dwellers. The Northeast U.S. Continental Shelf places in the high-risk category based on percentage and absolute number of coastal poor (present day estimate).

Revenues and Spatial Wealth Distribution:

Fishing and tourism depend on ecosystem services provided by LMEs. The Northeast U.S. Continental Shelf LME ranks in the highest revenue category in fishing revenues based on yearly average total ex-vessel price of US 2013 $3,873 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 $201,155 million places it in the highest revenue category as well. 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 the Northeast U.S. Continental Shelf 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 Northeast U.S. Continental Shelf LME HDI belongs to the highest HDI and lowest 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). The Northeast U.S. Continental Shelf 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 place in the high risk category (low 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 index to the Northeast U.S. Continental Shelf 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. In a sustainable development scenario, the risk index from sea level rise in 2100 is lowest, and which increases to high risk under a fragmented world development pathway.

Governance

Governance architecture:

None of the four transboundary fisheries agreements (NAFO, ICCAT, NASCO and NAMMCO) in this LME have formal linkages identified across the different stages of the policy cycle.
The overall scores for the ranking of risk were: