Scotian Shelf
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LME 8: Scotian Shelf

Bordering country:

Canada

LME total area:

412,676 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 (1.46 mg.m^-3) in April and a minimum (0.674 mg.m^-3) during June. The average CHL is 0.854 mg.m^-3. Maximum primary productivity (340 g.C.m^-2.y^-1) occurred during 1999 and minimum primary productivity (282 g.C.m^-2.y^-1) during 2011. There is a statistically significant increasing trend in Chlorophyll of 20.1 % from 2003 through 2013. The average primary productivity is 311 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 Scotian Shelf LME #08 has warmed by 1.46°C, thus belonging to Category 1 (super-fast warming LME). The thermal history of the Scotian Shelf LME #08 is similar to that of the Northeast U.S. Continental Shelf LME #07. These LMEs are connected by the Slope Current, which flows southwestward along the shelf break and upper continental slope. This connection explains the observed similarities between thermal histories of these LME: first, the cold spell of the mid-1960s, with the all-time minimum of 6.7°C in 1965 over the Scotian Shelf; and the most recent warming until present. As in LME #07, the year of 1965 can be considered a true breakpoint between two regimes characterized by long-term cooling before 1965 and long-term warming after 1965. The post-1965 warming led to the all-time maximum of 10.0°C in 2012, hence a 3.3°C warming in 37 years, making the Scotian Shelf one of the fastest warming LMEs. Over the late 1990s, the Scotian Shelf’s interannual variability was synchronized with that of the Northeast U.S. Continental Shelf LME #07 as evidenced by simultaneous minima in 1997, maxima in 1999, minima in 2004, and sharp increases from 2004 until present, in both LMEs. The most recent SST increase after 2004 led to the all-time maximum of 10.0°C in 2012, consistent and concurrent with the all-time maximum of 14.3°C in 2012 in the Northeast U.S. Shelf Continental LME #07 and the all-time maximum of 6.8°C in 2012 in the Newfoundland-Labrador Shelf LME #09.

Fish and Fisheries

The commercially exploited species in this LME include capelin, turbot, Atlantic halibut, white hake, silver hake, cod, haddock and Pollock, while pelagic species include Atlantic herring and Atlantic mackerel. Invertebrates include snow crab, northern shrimp and short fin squid.

Annual catch:

Total reported landings recorded a peak of 940,000 t in 1970 and declined to about one third of this level or 300,000 t in recent few years. Major changes include a dramatic decline in landings of cod, sliver hake and redfish.

Catch value:

However, the value of the reported landings reached its peak of 1.4 billion US$ (in 2005 real US$) in 1979, as a result of high value commanded by its landings of crustaceans.

Marine Trophic Index and Fishing-in-Balance index:

The MTI remained high until the early 1990s, when the cod stock collapsed, a clear case of ‘fishing down’ of the food web. The FiB index showed a similar trend, suggesting that the reported landings of lower-trophic level organisms did not compensate for the decline in the MTI over that period.

Stock status:

The Stock-Catch Status Plot shows that over 70% of commercially exploited stocks in the LME are either overexploited or have collapsed, with about 40% of the reported landings biomass supplied by fully exploited stocks.

Catch from bottom impacting gear:

The percentage of catch from the bottom gear type to the total catch reaches its maximum at 45% in 1973 and then this percentage fluctuated around 20% in the recent decade.

Fishing effort:

The total effective effort increased steadily from around 10 million kW in the mid-1950s to its peak at 270 million kW in 2005.

Primary Production Required:

The primary production required (PPR) to sustain the reported landings in this LME exceeded the observed primary production in the mid-1970s, but has declined in recent years. The extremely high PPR recorded in the mid-1970s was likely due to the accumulated biomass of cod stocks being exploited and not from exploitation of annual surplus production.

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 1of 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 increased to low in 2030 and decreased back to very low in 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 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 Scotian Shelf LME experienced an increase in MPA coverage from 70 km² prior to 1983 to 1,576 km² by 2014. This represents an increase of 2,154%, within the medium category of MPA change.

Cumulative Human Impact:

The Scotian Shelf LME experiences an above average overall cumulative human impact (score 4.0; maximum LME score 5.22), which is well above the LME with the least cumulative impact. It falls in risk category 4 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 (0.55; maximum in other LMEs was 1.20), UV radiation (0.55; maximum in other LMEs was 0.76), and sea surface temperature (1.56; maximum in other LMEs was 2.16). Other key stressors include commercial shipping, sea level rise, ocean based pollution, demersal destructive commercial fishing, and demersal non-destructive high-bycatch commercial fishing.

Ocean Health Index:

The Scotian Shelf LME scores above average on the Ocean Health Index compared to other LMEs (score 71 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 2 points compared to the previous year, due in large part to changes in the scores for clean waters. This LME scores lowest on natural products, carbon storage, tourism & recreation, and lasting special places goals and highest on mariculture, artisanal fishing opportunities, coastal protection, coastal economies, and biodiversity goals. It falls in risk category 3 of the five risk categories, which is an average 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 Scotian 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 those of Nova Scotia, Cape Breton and Prince Edward Islands, stretching over 130,408 km². A current population of 1.7 million is projected to decrease to 914,000 in 2100, and a density decreasing from 13 persons per km² in 2010 to 7 per km² by 2100. About 27% of coastal population lives in rural areas, and is projected to decrease to 25% in 2100.

Coastal poor:

The indigent population makes up 12% of the LME’s coastal dwellers. The Scotian Shelf places in the low-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 Scotian Shelf LME ranks in the medium revenue category in fishing revenues based on yearly average total ex-vessel price of US 2013 $613 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 $5,173 million places it in the low revenue category. On average, LME-based tourism income contributes 5% 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 Scotian Shelf 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 Scotian Shelf LME HDI belongs to the highest HDI and lowest risk category. Based on an HDI of 0.899, this LME has an HDI Gap of 0.101, 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 Scotian 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 estimated to place in the low risk category (low HDI) because of reduced income level and smaller 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 Scotian 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 low risk under a fragmented world development pathway.

Governance

Governance architecture:

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