Grey seal pup production
The UK target was met: the number of grey seals born each year in both the Greater North Sea and the Celtic Seas has increased substantially since 1992 and has continued to rise in recent years (from 2009 to 2014).
Background
UK target on grey seal pup production
This indicator is used to assess progress against the following target, which is set in the UK Marine Strategy Part One (HM Government, 2012): “At the scale of the Marine Strategy Framework Directive sub-regions, marine mammal productivity is not significantly affected by human activities There should be no statistically significant decline in seal pup production caused by human activities.”
Key pressures and impacts
This indicator, along with the indicator on seal abundance and distribution, can respond to many influences including disease, competition with other species, changes in distribution and abundance of their prey, disturbance, and interactions with fisheries. Grey seals were hunted into the 20th-century but are now protected throughout the UK.
Measures taken to address the impacts
Measures to protect seals are set out in the UK Marine Strategy Part Three (HM Government, 2015). These include protection through many national, European, and international conventions, agreements, and regulations that aim to manage the impacts of human activities on the seal population.
Monitoring, assessment, and regional cooperation
Areas that have been assessed
The European population of breeding grey seals has been subdivided into a number of assessment units to describe changes in pup production at a ‘local’ scale (Figure 1). These spatial units are the same as those used for the harbour seal abundance assessment and for grey seal distribution. Assessments of grey seal pup production were possible for all UK North Sea assessment units (where grey seals breed) and only some Celtic Seas assessment units.
Figure 1: Assessment units for this assessment. 1. Northern Ireland, 2. South West Scotland, 3. West Scotland, 4. The Western Isles, 5. North Coast and Orkney, 6. Shetland, 7. Moray Firth, 8. East Scotland, 9. North East England, 10. South East England, 11. South England, 12. South West England, 13. Wales, 14. North West England, 15. French North Sea and Channel Coast, 16. Belgium Coast and Dutch Delta, 17. The Wadden Sea, 18. Limfjorden, 19. Kattegat, 20. Northern Skagerrak and Oslo Fjord, 21. Norwegian West Coast, south of 62N. (Source: Eurostat).
Monitoring and assessment methods
Grey seal pups (Figure 2) are counted at major breeding sites (‘colonies’) usually using aerial photographic survey methods; where these are not possible, ground counts or boat-based counts may be conducted. Pup counts are then converted to total pup production at each colony by using an established statistical model that describes how the number of pups at the site varies over the season.
Figure 2. Atlantic grey seal female with pup (courtesy of Chris Morris, Sea Mammal Research Unit)
Assessment thresholds
The target is met if a) grey seal pup production during 2009 to 2014 has not declined by more than an average of 1 % per year, and/or b) grey seal pup production has not decreased by more than 25 % since the baseline year (1992 or the start of the time series, if later). These thresholds are based on those used in the OSPAR Intermediate Assessment (OSPAR Commission, 2017).
Regional Cooperation
This indicator is part of the OSPAR Intermediate Assessment (OSPAR Commission, 2017) and was led by the UK.
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Further information
Grey seals only occur in the North Atlantic, Barents and Baltic Seas, gathering to breed at long-established colonies located on islands, sandbanks and mainland coastlines around UK coasts. Within north-west Europe, the greatest concentration of grey seals is found around UK coasts, especially in Scottish coastal waters. Approximately 38 % of the world’s grey seals breed in the UK, and 88 % in Scotland, with the main concentrations in the Outer Hebrides and Orkney.
Seals have been impacted by human activity for a long time, and it is not possible to know the undisturbed state, nor the current carrying capacity that could be attained alongside sustainable human activity. Except for hunting, no straightforward link has yet been identified between pup production and human activities, although a number of human activities may, at least in part drive this change. If changes in pup production are detected, this signals a need to investigate the cause and to determine if management measures should be taken.
Assessment method
Grey seal pups are counted at major breeding sites usually using aerial photographic survey methods (Figure 3); where these are not possible, ground counts or boat-based counts may be conducted (for example, Stringell and others, 2014). Multiple counts per colony are generated, spread across the breeding season (September to February, depending on colony location).
Figure 3: Aerial survey image of grey seal colony (courtesy of Sea Mammal Research Unit).
In the UK, pup counts are converted to total pup production at each colony by using an established statistical model that describes how the number of pups at the site varies over the season (Special Committee on Seals, 2014). Both types of estimates (maximum count and modelled pup production) are used in this assessment. From calculations across Scottish colonies, maximum pup counts represent 0.82 (95 % confidence interval: 0.81 – 0.83) of the total pup production. Hereafter, both types of estimates will be referred to collectively as ‘pup production’.
Colony survey frequency varies by assessment unit and ranges from every year to approximately every five years. The details of current, known seal monitoring programmes for each assessment unit are given in Table 1.
Table 1. Details of current and known grey seal monitoring programmes
|
Assessment unit |
Pup production (total number of pups produced during the entire breeding season) |
|
1. Northern Ireland |
Sea Mammal Research Unit partial survey 2002, 2005; boat based monthly surveys of Strangford Lough |
|
2. Southwest Scotland |
No formal monitoring as population very low |
|
3. West Scotland |
Repeat aerial surveys, annual to 2010, biennial thereafter |
|
4. Western Isles |
Repeat aerial surveys, annual to 2010, biennial thereafter |
|
5. North Coast & Orkney |
Repeat aerial surveys, annual to 2010, biennial thereafter |
|
6. Shetland |
Ground/boat counts, annual since 2004 |
|
7. Moray Firth |
Repeat aerial surveys, annual to 2010, biennial thereafter |
|
8. East Scotland |
Repeat aerial surveys, annual to 2010, biennial thereafter |
|
9. Northeast England |
Annual ground counts |
|
10. Southeast England |
Annual ground counts |
|
11. South England |
No formal monitoring as population very low |
|
12. Southwest England |
No formal monitoring as population very low |
|
13. Wales |
Annual ground counts of some colonies (data not available for this assessment), partial survey 1002,1993,1994 and 2005 |
|
14. Northwest England |
No formal monitoring as population very low |
Despite their ability to travel long distances, individual mature grey seals of both sexes are usually faithful to particular breeding sites and may return to within 10–100 m of individual breeding locations (Pomeroy and others, 2000). The Greater North Sea and UK parts of the Celtic Seas were divided into 21 assessment units to describe changes in pup production at a ‘local’ scale (Figure 1). Direct impacts on pup production, such as disturbance, persecution, and food availability may be more detectable at these smaller scales.
It is important to consider that assessment units, do not represent demographically independent populations. Additionally, survey coverage and monitoring effort is higher where breeding grey seals are most abundant. In many assessment units, monitoring is undertaken in specific areas by local organisations and does not form part of synoptic surveys.
These assessment units are the same as those used for the harbour seal abundance and distribution assessment under the seal abundance and distribution indicator. The assessment units in the Greater North Sea are broadly similar to those previously defined as OSPAR Ecological Quality Objective sub-units (OSPAR Commission, 2010).
Baselines
Seals have been impacted by human activity for a long time, and it is not possible to know the undisturbed state, nor the carrying capacity that could be attained under current management arrangements. Time series data for grey seal pup production does not indicate a baseline representing unimpacted conditions. The method adopted here assesses grey seal pup production data using both a fixed baseline and a rolling baseline with associated thresholds.
The fixed-baseline year of 1992 was used, the baseline year used by some Member States for seals under the Habitats Directive (European Commission, 1992). In assessment units for which grey seal pup production data for 1992 were not available, the start of the data time series was used as the baseline. It should be noted that where data series do not extend back to 1992 and a shorter timescale is assessed, a particular percentage decline since the baseline is not equivalent to those assessed units where data does extend to 1992, for example a 25 % decline since 2003 describes a more rapid contraction in the population than a 25 % decline since 1992.
As the arbitrarily assigned baseline does not necessarily reflect an unimpacted state, trends in seal populations can be assessed. A short-term rate-based threshold was also adopted that uses a rolling baseline (Method 1; OSPAR Commission, 2012). Here, the average annual rate of population- change over consecutive six-year periods (in line with the Marine Strategy Framework Directive reporting cycle) was assessed against the next. The rolling baseline provides a means to observe changes in population size compared with the previous six-year assessment period, rather than relying solely on a historical fixed baseline, which may reflect a time when the population was already depleted due to anthropogenic pressures.
A potential problem with this type of quantitative trend threshold, known as a ‘shifting baseline’ is that each successive assessment uses a different starting point as a basis for comparison. This could result in a substantial cumulative decrease, occurring over more than one six-year assessment period, not being flagged as a problem because in each six-year period the rate of decline remained below the threshold (OSPAR Commission, 2012). Use of two types of baseline and associated thresholds can provide an indicator that will warn against both a slow but long-term steady decline (the problem of ‘shifting baselines’ associated with only having a rolling baseline) and against a recovery followed by a subsequent decline (potentially missed with a fixed baseline set below reference conditions).
Thresholds
Indicator thresholds were set as a percentage deviation from the baseline value (Method 3; OSPAR Commission, 2012).Two thresholds were used to assess grey seal pup production in each assessment unit:
- No decline in grey seal pup production of > 1 % per year in the previous six-year period (a decline of up to 6 % over six years).
- No decline in grey seal pup production of > 25% since the fixed baseline in 1992 (or closest time).
The two thresholds together would be able to act as a trigger for the investigation of management measures needed to promote a steady recovery.
Assessing change in pup production
Pup production estimates from all colonies reported were summed to make assessments within each assessment unit. Quantitative assessments of trends in pup production were only completed for those units where a sufficient number of annual data points (at least three) were available.
Grey seal pup production estimates were assessed in relation to a baseline set as 1992 (or the start of the time series where this was later), and by calculating the average rate of annual population change within the last reporting period (2009 to 2014).
To determine the change in pup production since the baseline year, Generalised Linear models (GLMs) or Generalised Additive Models (GAMs) were fitted to the sum of pup production data within an assessment unit and with a quasi-poisson error distribution and log link using all available annual survey data in the range 1992 to2014. The percentage change in pup numbers since baseline year (Δ abundance) and 80 % confidence intervals were calculated from fitted values (equation shown in Figure 4). Although no formal hypothesis testing was conducted, 80% confidence intervals were calculated to reflect the choice to set the significance level, α, equal to 0.20 or 20%.
Figure 4. Calculation of the long-term trend (change, denoted by Δ) in abundance where A is the count fitted by the model in the baseline year, and B is the count fitted by the model in the most recent survey year.
To estimate the annual change in pup production over the previous six-year reporting period, a linear trend was fitted to the sum of all available data in each assessment unit for the period 2009 to2014. Generalised linear models were fitted to the sum of pup production data within an assessment unit with a quasi-Poisson error distribution and log link. Annual growth rate (%) and 80 % confidence intervals were estimated for each of the assessment units. Although no formal hypothesis testing was conducted, 80 % confidence intervals were calculated to reflect the choice to set the significance level, α, equal to 0.20 or 20 %.
Indicator metrics and associated confidence intervals were assessed against two thresholds: the average annual growth rate (%) and 80 % confidence intervals within the last reporting period were less than -1% per year, and the percentage change in abundance since baseline year (Δbaseline) and 80 % confidence intervals were less than -25%. If the 80 % confidence intervals encompassed the threshold, the assessment was classified as ‘inconclusive’.
The Statistical power of detecting a change in pup production
There are many causes for variable pup counts in addition to true changes in pup production including: variation in weather, or recent disturbance at a colony. It is therefore advisable to examine the variability in survey counts and incorporate this variability into trend estimates. ICES Working Group for Marine Mammal Ecology (ICES, 2014) provided general advice on the need to understand the statistical power of current and proposed monitoring programmes.
In the present context, statistical power is the percentage confidence in not missing a significant decline. Statistical power depends on the sample size (number of surveys), the level of statistical significance set (α-level), variance in the counts, and the magnitude of the trend, (-1 % and -25 %). ICES (2014) recommended that monitoring should achieve a minimum of 80 % power – which equates to a 20 % chance of making a Type II error (the frequency with which a true decline will not be detected). The same group also recommended that the threshold for detection of a statistically ‘significant’ trend be relaxed from the traditional α = 0.05 to α = 0.20. The α parameter, or statistical significance level, equates to the probability of concluding that a statistically significant trend exists when in fact it does not (Type I error). A α value of 0.2 and power of 80 % means there is an equal probability of making an incorrect conclusion (either Type I or Type II error) about the detection of a trend.
Current monitoring programmes vary in the level of statistical power achievable. To carry out a full study of retrospective power to detect changes in the observed population trends, detailed information about the between- and within-year variability in all survey counts would be necessary. We did not undertake a full assessment of power here, but confidence intervals also provide a measure of confidence in the assessment. They describe the frequency with which the true, unobservable, population parameter (here, the mean count) could be expected to fall within the intervals. Where confidence intervals encompass the threshold effect size, the data do not provide conclusive evidence for the calculated value being above or below the threshold value.
Assessing UK target for grey seal pup production
Progress towards the UK target (HM Government, 2012) was assessed for grey seal pup production in each Marine Strategy Framework Directive sub-region by integrating the results of the assessments in each constituent UK assessment unit. The assessment results in each assessment unit were scored as shown in Table 2. Greater weight in the scoring was given to significant long-term changes. If significant short-term and long-term trends were detected in a single assessment unit, each trend was scored and then added to the other. Scores were averaged across assessment units to provide the overall assessment for grey seal pup production for each Marine Strategy Framework Directive sub-region (Table 3).
Table 2. Scoring system for assessment units used to integrated results at larger spatial scale.
|
Assessment unit result |
Assessment summary |
Integration score |
|
A significant decline in grey seal pup production of > 25 % since the fixed baseline in 1992 (or closest time). |
Long-term decline |
-2 |
|
Non-significant decline in grey seal pup production of > 25 % since the fixed baseline in 1992 (or closest time). A decline was detected, but the confidence intervals span the threshold. |
Inconclusive long-term decline |
-1 |
|
Significant decline in grey seal pup production of > 1 % per year in the previous six-year period (a decline of up to 6 % over six years). |
Short-term decline |
-1 |
|
Non-significant decline in grey seal pup production of > 1 % per year in the previous six-year period (a decline of up to 6 % over six years). A decline was detected, but the confidence intervals span the threshold. |
Inconclusive short-term decline |
-0.5 |
|
Not enough data points |
Insufficient data |
0 |
|
Non-significant increase in grey seal pup production of > 1 % per year in the previous six-year period (a decline of up to 6 % over six years). An increase was detected, but the confidence intervals span the threshold. |
Inconclusive short-term increase |
0.5 |
|
Significant increase in grey seal pup production of > 1 % per year in the previous six-year period (a decline of up to 6 % over six years). |
short-term increase |
1 |
|
Non-significant increase in grey seal pup production of > 25% since the fixed baseline in 1992 (or closest time). An increase was detected, but the confidence intervals span the threshold. |
Inconclusive long-term increase |
1 |
|
Significant increase in grey seal pup production of > 25% since the fixed baseline in 1992 (or closest time). |
Long-term increase |
2 |
Table 3. Overall sub-region assessment scores.
|
MSFD sub-region total score |
MSFD sub-region assessment outcome |
|
Greater than zero |
UK target is met |
|
Equals zero |
Uncertain |
|
Less than zero |
UK target is not met |
Results
Findings from the 2012 UK Initial Assessment
Grey seal pup production increased rapidly following the end of culling in the 1970s. A further factor is in part due to the increased availability of breeding sites following the abandonment of human settlements on remote islands, including automation of lighthouses. The increases in pup production had slowed by the time of the initial assessment, probably due to density- dependent factors affecting the population as a whole (HM Government, 2012).
Latest Findings
Status Assessment
This status assessment, like the Initial Assessment, is based on trends in pup production, but unlike the initial assessment, compares the trends against thresholds. Grey seal pup production has increased in both the long and short-term within almost all assessment units (Figure 5). As there is no decline in pup production in these areas, the targets for pup production have been met. The only exception is Shetland, where there was a significant long-term decline. However, there is low confidence that the results from Shetland represent an actual decline, because the counts varied substantially from year to year. This variance is likely the result of difficulties in counting pups in Shetland.
Trend assessment
The target has been met in both UK Marine Strategy Framework Directive sub-regions.
Figure 5. Assessment of changes in grey seal pup production (a) short-term trend (2009 to2014), assessed against no decline greater than 1 % per year; and (b) long-term trend (1992 to2014), assessed against no decline in abundance of more than 25 %. 1992 was used as a baseline year, except in assessment unit 6 (2004) and assessment unit 7 (1997) due to insufficient data.
Further information
The assessment results presented in Figure 5 are derived from the values for rates of change in pup production presented in Table 4.
Table 4. Short-term trends (2009 to 2014) and long-term changes (baseline year to 2014) in grey seal pup production in each assessment unit. Superscripts on numeric results indicate assessment result: (*) not enough data points, (+) decline less than threshold, (ǂ) inconclusive (CI spans threshold), blanks indicate too few breeding seals present. T1: Growth rate 2009 to 2014 is the annual growth (%) in counts between 2009 and 2014; T2: Δbaseline is the change in numbers since the baseline year. Upper and lower 80% confidence intervals are given for both thresholds based on modelled growth rates (upperCIT1, lowerCIT,1 and upper CIT2, lower CIT2 respectively). Years T1 and Years T2 are the number of years of pup count data in the periods 2009 to 2014 and 1992 to 2014 respectively. The observed change in pup production since the baseline year, not from modelled data, is denoted by Observed Δbaseline. The baseline year refers to 1992 or the start of the time series. The most recent count gives current estimates of total pup production. Relative size is the most recent estimate of total pup production expressed as a proportion of the total for all assessment units. c These numbers are a maximum number of pups counted, in other assessment units the number given is modelled pup production (the total number of pups born in the season).
|
Sub-Region |
assessment unit |
T1: Growth rate2009-2014 |
upperCIT1 |
lowerCIT1 |
YearsT1 |
T2: Δbaseline |
upperCIT2 |
lowerCIT2 |
Observed Δbaseline |
YearsT2 |
Baseline year |
Most recent count |
Relative size |
|
|
Greater North Sea |
5 |
North Coast & Orkney |
6+ |
6+ |
6+ |
3+ |
121+ |
138+ |
105+ |
130+ |
20+ |
1992 |
23483 |
0.41 |
|
6 |
Shetland |
-4ǂ |
-1ǂ |
-8ǂ |
4ǂ |
-14+ |
-4+ |
-23+ |
-19+ |
9+ |
2004 |
761 |
0.01 |
|
|
7 |
Moray Firth |
* |
* |
* |
2* |
166+ |
245+ |
108+ |
201+ |
9+ |
1997 |
1602 |
0.03 |
|
|
8 |
East Scotland |
8+ |
10+ |
7+ |
3+ |
347+ |
415+ |
290+ |
316+ |
20+ |
1992 |
5207 |
0.09 |
|
|
9 |
Northeast England |
6+ |
7+ |
4+ |
4+ |
54+ |
78+ |
33+ |
63+ |
21+ |
1992 |
1603 |
0.03 |
|
|
10 |
Southeast England |
13+ |
14+ |
13+ |
4+ |
1624+ |
1719+ |
1535+ |
1580+ |
21+ |
1992 |
3359 |
0.06 |
|
|
11 |
South England |
|||||||||||||
|
Celtic Seas |
12 |
Southwest England |
* |
* |
* |
* |
* |
* |
* |
* |
* |
|||
|
13 |
Wales |
* |
* |
* |
0* |
25+ |
30+ |
20+ |
26+ |
4+ |
1992 |
1650c |
0.03 |
|
|
14 |
Northwest England |
|||||||||||||
|
1 |
Northern Ireland |
* |
* |
* |
* |
* |
* |
* |
* |
* |
||||
|
2 |
Southwest Scotland |
|||||||||||||
|
3 |
West Scotland |
6+ |
10+ |
2+ |
3+ |
31+ |
39+ |
23+ |
45+ |
20+ |
1992 |
4088 |
0.07 |
|
|
4 |
Western Isles |
5+ |
5+ |
5+ |
3+ |
13+ |
23+ |
4+ |
16+ |
20+ |
1992 |
14136 |
0.25 |
|
The values in Table 4 were estimated from trend models fit to observed annual pup production within each assessment unit, where there were sufficient time-series data. The observed and modelled estimates of annual pup production are plotted for each assessment unit in Figures 6 and 7. A striking trend is the continued rapid growth of grey seal pup production in the Greater North Sea. The slower growth rates of colonies in the Celtic Seas suggest that these areas may be approaching carrying capacity (Special Committee on Seals, 2014).
Figure 6. Modelled trends in grey seal pup production in each Greater North Sea Assessment unit. Points denote observed annual pup production, coloured according to 4 periods from 1992 to 2014, 1992 to 1996 (pink), 1997 to 2002 (purple), 2003 to 2008 (orange), 2009 to 2014 (green). Modelled trends in annual pup production are shown for the period from start of the time-series (baseline year) to 2014 (dash line) and 2009 to 2014 (dotted and dashed line). The 80% confidence interval around each trend is shown as a greyed area on the plot.
Figure 7. Modelled trends in grey seal pup production in each Celtic Seas assessment unit. Points denote observed annual pup production, coloured according to 4 periods from 1992 to 2014, 1992 to 1996 (pink), 1997 to 2002 (purple), 2003 to 2008 (orange), 2009 to 2014 (green). Modelled trends in annual pup production are shown for the period from start of the time-series (baseline year) to 2014 (dash line) and 2009 to 2014 (dotted and dashed line). The 80% confidence interval around each trend is shown as a greyed area on the plot.
Integration of grey seal pup production assessment across the assessment units for each Marine Strategy Framework Directive subregion. indicated that the target had been met for both the Celtic Seas and the Greater North Sea (Tables 5 and 6).
Table 5. Integration of assessment unit trends for the Greater North Sea.
|
Assessment unit |
Assessment summary |
Integration score |
Pup production estimate for 2014 |
|
5. North Coast and Orkney |
Long-term and short-term increases |
3 |
23,758 |
|
6. Shetland |
Inconclusive long and short-term declines |
-1.5 |
3,875 |
|
7. Moray Firth |
Long-term increase |
2 |
|
|
8. East Scotland |
Long-term and short-term increases |
3 |
|
|
9. Northeast England |
Long-term and short-term increases |
3 |
1,600 |
|
10. Southeast England |
Long-term and short-term increases |
3 |
5,027 |
|
Average across Greater North Sea |
2.1 |
|
|
Table 6. Integration of assessment unit trends for the Celtic Sea.
|
Assessment unit |
Assessment summary |
Integration score |
Pup production estimate for 2014 |
|
11. South England |
Indicator not applicable |
- |
|
|
12. South-west England |
Insufficient data |
0 |
250 |
|
13. Wales |
Long-term increase |
2 |
1,650 |
|
14. North-west England |
Indicator not applicable |
- |
|
|
1. Northern Ireland |
Insufficient data |
0 |
100 |
|
2. South-west Scotland |
Indicator not applicable |
- |
|
|
3. West Scotland |
Long-term and short-term increases |
3 |
4,054 |
|
4. Western Isles |
Long-term and short-term increases |
3 |
14,316 |
|
Average across Celtic Seas |
1.6 |
|
|
The assessment is undertaken using data with a spatial coverage and temporal extent that are mostly sufficient for the area assessed but gaps are apparent in certain areas. As such, confidence in data availability is moderate.
Conclusions
These results for pup production, which show that the associated UK target has been met, should be considered alongside those for the indicator on grey seal abundance and distribution. Both indicators show an improvement in the condition of the grey seal population in the North East Atlantic. It is likely that this population is recovering from a time when it was significantly depleted by human activities.
Knowledge gaps
- This indicator is intended to assess population condition, but it only covers part of the annual life-cycle of grey seals. Assessments of pup production in combination with other demographics such as adult survival and the post-weaning survival of pups along with measures of body condition (blubber thickness, for example) would give a more comprehensive indication of the health of grey seal populations.
- There is a lack of information on human impacts on pup production, how adult grey seals move between assessment units, including how this impacts populations.
Further information
- Pup production, when used on its own, is not a meaningful indicator of population condition. An ideal measure of population condition would include information on female fecundity and pup survival. Such demographic parameters are only available where long-term and detailed monitoring of colonies exists such as in the Isle of May in Scotland. Another good indicator of population condition would be changes in body condition that include blubber thickness, or condition indices.
- From the present data, it is not possible to exclude human influence on pup production. Even without pressure from human activities, it is clear that pup production cannot increase indefinitely. Further demographic studies could help predict the natural carrying capacity for the number of grey seals in the North East Atlantic and provide an indication of likely future trends in pup production, with and without impacts from humans.
- A demographic link between assessment units is possible, but the extent of movement of adults between colonies and how this has an influence on local pup production remains poorly understood. Further international studies on the movements of individual seals could help better understand this and even prevent unintended disturbance of these inter-colony exchanges.
- It was not possible to make a quantitative assessment in all of the assessment units for a number of reasons. One is that grey seals may not breed in sufficient numbers in some assessment units to warrant regular monitoring. In such cases, the assessment area was considered ‘not applicable’ to this assessment. The remaining assessment gaps were due to a lack of sufficient annual data points to perform a quantitative assessment of the time-series. Infrequent monitoring may be because there are relatively few animals breeding there and/or be related to the difficulty in assessing breeding sites during the autumn and winter. Continued support for the long-term seal monitoring programmes in place will ensure that adequate data are collected to provide quantitative assessments of grey seal pup production for those areas. The aggregation of data across national programmes in the North East Atlantic provides a possibility for meta-analyses that place regional/national population trends into the wider regional context.
References
European Commission (1992) ‘Council Directive 92/43/EEC of 21 May 1992 on the conservation of natural habitats and of wild fauna and flora’ (viewed on 23 November 2018)
HM Government (2012) ‘Marine Strategy Part One: UK Initial Assessment and Good Environmental Status’ (viewed on 5 July 2018)
HM Government (2015) ‘Marine Strategy Part Three: UK Programme of Measures’ (viewed on 5 July 2018)
ICES (2014) ‘Report of the working group on Marine Mammal Ecology (WGMME). 10-13 March 2014, Woods Hole, Massachusetts, USA’. ICES CM 2014/ACOM: 27 (viewed on 23 November 2018)
OSPAR Commission (2010) ’The OSPAR system of Ecological Quality Objectives for the North Sea, a contribution to OSPAR’s Quality Status Report 2010’ (viewed on 23 November 2018)
OSPAR Commission (2012) ’MSFD Advice Manual and Background Document on Biodiversity. Version 3.2. OSPAR Biodiversity Series’ (viewed on 23 November 2018)
OSPAR Commission (2017) ‘Intermediate Assessment 2017’ (viewed on 21 September 2018)
Pomeroy PP, Twiss SD and Redman P (2000) ‘Philopatry, site fidelity, and local kin associations within grey seal breeding colonies’. Ethology: 899–919 (viewed on 23 November 2018)
Special Committee on Seals (2014) ‘Scientific advice on matters related to the management of seal populations, 2014’ Special Committee on Seals (SCOS), Sea Mammal Research Unit (viewed on 11 November 2018)
Stringell T, Millar C, Sanderson W, Westcott S and McMath M (2014) ‘When aerial surveys will not do: grey seal pup production in cryptic habitats of Wales’ Journal of the Marine Biological Association of the United Kingdom 94: 1155-1159 (viewed on 23 November 2018)
Assessment metadata
| Assessment Type | UK MSFD Indicator Assessment |
|---|---|
D1/D4/D6 Biodiversity and Food Webs, Seals | |
| Point of contact email | marinestrategy@defra.gov.uk |
| Title | Grey Seal Pup Production |
| Resource abstract | Common indicator assessment of grey seal pup production. Applicable to the Greater North Sea and Celtic Seas (OSPAR Regions II & III) |
| Linkage | |
| Conditions applying to access and use | http://www.ospar.org/site/assets/files/1215/ospar_data_conditions_of_use.pdf |
| Assessment Lineage | |
| Indicator assessment results | |
| Dataset metadata | |
| Links to datasets identifiers | https://odims.ospar.org/en/submissions/ospar_grey_seal_pup_prod_2017_01/ https://odims.ospar.org/en/submissions/ospar_grey_seal_pup_prod_2017_02/ |
| Dataset DOI | Please, see metadata details and links above |
The Metadata are “data about the content, quality, condition, and other characteristics of data” (FGDC Content Standard for Digital Geospatial Metadata Workbook, Ver 2.0, May 1, 2000).
Metadata definitions
Assessment Lineage - description of data sets and method used to obtain the results of the assessment
Dataset – The datasets included in the assessment should be accessible, and reflect the exact copies or versions of the data used in the assessment. This means that if extracts from existing data were modified, filtered, or otherwise altered, then the modified data should be separately accessible, and described by metadata (acknowledging the originators of the raw data).
Dataset metadata – information on the data sources and characteristics of data sets used in the assessment (MEDIN and INSPIRE compliance).
Digital Object Identifier (DOI) – a persistent identifier to provide a link to a dataset (or other resource) on digital networks. Please note that persistent identifiers can be created/minted, even if a dataset is not directly available online.
Indicator assessment metadata – data and information about the content, quality, condition, and other characteristics of an indicator assessment.
MEDIN discovery metadata - a list of standardized information that accompanies a marine dataset and allows other people to find out what the dataset contains, where it was collected and how they can get hold of it.
Recommended reference for this indicator assessment
Ian Mitchell1, Nora Hanson2, Eunice Pinn1, Debbie Russell2, John Weinberg1 and Jane Hawkridge1 2018. Grey Seal Pup production. UK Marine Online Assessment Tool, available at: /biodiversity-food-webs-and-marine-protected-areas/seals/grey-seal-pup-production/
* Adapted from OSPAR Intermediate Assessment 2017 on Grey Sea Pup Production
1Joint Nature Conservation Committee
2Sea Mammal Research Unit UK