North Sea
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LME 22: North Sea

Bordering countries:

Belgium, Denmark, France, Germany, Netherlands, Norway, Sweden, United Kingdom

LME total area:

690,041 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 medium.

Productivity

Chlorophyll-A:

The annual Chlorophyll a concentration (CHL) cycle has a maximum peak (2.68 mg.m^-3) in January and a minimum (0.813 mg.m^-3) during July. The average CHL is 0.945 mg.m^-3. Maximum primary productivity (385 g.C.m^-2.y^-1) occurred during 1998 and minimum primary productivity (282 g.C.m^-2.y^-1) during 2005. There is a statistically insignificant increasing trend in Chlorophyll of 7.07 % from 2003 through 2013. The average primary productivity is 326 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 North Sea LME #22 has warmed by 0.93°C, thus belonging to Category 2 (fast warming LME). The thermal history of this LME has been uniform. Like in the Baltic Sea LME, the high warming rate of the North Sea is a result of two factors combined: (1) the cold epoch of the late 1970s-1980s (preceded by another cold epoch, of the 1960s), and (2) the rapid warming that commenced in the late 1980s. During this warming epoch, the North Sea was one of the fastest warming LMEs in the World Ocean (Belkin, 2009). Recent years saw a reversal of the post-1979 warming. After peaking at >11°C in 2002-2006, SST dropped down to 10.2°C by 2010. The similarity between the North Sea and Baltic Sea SST variations is especially noteworthy since oceanic circulation directly impacts the North Sea, but not the Baltic Sea.

Fish and Fisheries

Fishing is a long-established activity in the North Sea LME and there is a wealth of fisheries data. The most important species for human consumption represented in the catch are cod-like fishes (cod, saithe, haddock, etc.), herring, sprat and flatfishes.

Annual catch:

Landings from the industrial fishery consist mainly of sand eel, Norway pout and sprat. The North Sea is a highly productive LME that, on average, supported total reported landings of over 3 million t per year from the mid-1960s to the early 1990s, with peak landings of 3.9 million t in 1968.

Catch value:

The value of the reported landings reached 6.8 billion US$ (in 2005 real US$) in 1977, following which it steadily declined.

Marine Trophic Index and Fishing-in-Balance index:

The MTI has shown a steady decline since 1970, an indication of ‘fishing down’ of the food web in the LME, while the FiB index has been on a similar decline over the past three decades.

Stock status:

The Stock-Catch Status Plots, based on the first analysis of an LME using such plots indicate that the number of collapsed and overexploited stocks have been increasing, accounting for close to 60% of all commercially exploited stocks in the LME. A majority of the reported landings biomass, particularly in recent years, is supplied by overexploited and rebuilding stocks.

Catch from bottom impacting gear:

The percentage of catch from the bottom gear type to the total catch increased from 20% in the 1950s to its first peak at around 60% in 1996. In the recent decade, this percentage ranged between 30 and 50%.

Fishing effort:

The total effective effort continuously increased from around 180 million kW in the 1950s to its peak at 540 million kW in the mid-2000s.

Primary Production Required:

The primary production required (PPR) to sustain the reported landings in this LME reached an extremely high level, over 70% of the observed primary production in the late 1960s, but has declined to less than 40% 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 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 high (4). 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 high (4). According to the Global Orchestration scenario, this remained the same in 2030 and 2050.

POPs:

The North Sea LME has 11 samples at 11 locations. The average concentration (ng.g^-1 of pellets) was 145 (range 43 – 446 ng.g^-1) for PCBs, 9.9 (range 2 – 39 ng.g^-1) for DDTs, and 2.4 (range not detected – 6.1 ng.g^-1) for HCHs. The PCBs average corresponds to risk category 3 and DDTs and HCHs averages correspond to risk category 2, of the five risk categories (1 = lowest risk; 5 = highest risk). Diffuse pollution by PCBs throughout the coast is noticeable, with higher pollution in the Dutch coast (105 – 281 ng.g^-1). This is probably due to legacy pollution. Continuous monitoring is recommended and more locations should be monitored to examine spatial variation. Total DDT concentrations are relatively low but the proportion of DDT is dominant, suggesting recent inputs.

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 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 North Sea LME experienced an increase in MPA coverage from 2,960 km² prior to 1983 to 16,846 km² by 2014. This represents an increase of 469%, within the low category of MPA change.

Cumulative Human Impact:

The North Sea LME experiences one of the highest overall cumulative human impact (score 4.87; maximum LME score 5.22). It falls in risk category 5 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 (0.62; maximum in other LMEs was 1.20), UV radiation (0.59; maximum in other LMEs was 0.76), sea level rise (0.36; maximum in other LMEs was 0.71), and sea surface temperature (1.44; maximum in other LMEs was 2.16). Other key stressors include commercial shipping, nutrient pollution from land, ocean based pollution, pelagic high-bycatch commercial fishing, invasive species, and all three types of demersal commercial fishing (demersal destructive, non-destructive low-bycatch, and non-destructive high-bycatch).

Ocean Health Index:

The North Sea LME scores above average on the Ocean Health Index compared to other LMEs (score 80 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. This LME scores lowest on mariculture and iconic species goals and highest on artisanal fishing opportunities, natural products and lasting special places 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 409 034 km². A current population of 81 437 thousand in 2010 is projected to increase to 86 764 thousand in 2100, with a density of 199 persons per km² in 2010 reaching 212 per km² by 2100. About 18% of coastal population lives in rural areas, and is not projected to change in share in 2100.

Coastal poor:

The indigent population makes up 5% of the LME’s coastal dwellers. This LME places in the very low-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 very high-revenue category in fishing revenues based on yearly average total ex-vessel price of US 2013 $2 497 million for the period 2001-2010. Fish protein accounts for 10% of the total animal protein consumption of the coastal population. Its yearly average tourism revenue for 2004-2013 of US 2013 $338 271 million places it in the very high-revenue category. On average, LME-based tourism income contributes 10% 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 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 0.900, this LME has an HDI Gap of 0.100, 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 high-risk category (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 medium-risk (medium threat) category. The combined contemporaneous risk due to extreme climate events, degrading LME states and the level of vulnerability of the coastal population, is medium. In a sustainable development scenario, the risk index from sea level rise in 2100 is very low, and increases to high risk under a fragmented world development pathway.

Governance

Governance architecture:

In this LME, the policy cycles relating to the key issues of fisheries and pollution are associated with well-established transboundary arrangements that are among the strongest globally. However, there does not appear to be much integration among these processes.
The overall scores for the ranking of risk were: