C1: Clean seas: marine litter
Short Description
This indicator of clean seas shows changes in the amount of litter in the marine environment, including litter on beaches, on the seafloor and floating litter. Beach litter surveys are completed annually or quarterly and cover a representative number of beaches. Data from benthic trawl surveys, typically carried out for fish stock assessments, are used to monitor the amount of litter on the seafloor. After each tow, all litter items are emptied from the net and counted and classified. Beached fulmars or individuals accidentally killed are collected as part of a monitoring programme in the Greater North Sea to assess the plastics found in their stomachs. Fulmars forage exclusively at sea, generally at the surface of the water. The amount of plastic they ingest can be used as a proxy for the abundance of floating litter in their environment and how this is changing. Indicators for seafloor litter, beach litter and plastic found in fulmar stomachs have been developed and expert groups are working to improve the data. Additional monitoring programmes are being developed to record the amount of microplastics in sediment and in biota.
Readiness and links to data
This indicator shows three aspects of litter in the marine environment: a) beach litter b) plastic in fulmar stomachs and c) seafloor litter.
The beach litter component of this interim indicator is drawn from an assessment of beach litter, developed by the Marine Conservation Society for Defra (project code ME5438) to support reporting under the Convention for the Protection of the Marine Environment of the North-East Atlantic (OSPAR) and UK Marine Strategy. This replaces an assessment previously presented here, reported under the UK Marine Strategy in 2019. The newer assessment is considered to be more statistically robust, as it is based on quarterly surveys of the same subset of beaches, as opposed to annual surveys of often differing beaches.
Data on the litter content of fulmar stomachs are published in the latest research report from Wageningen University to Defra (project code ME5227).
Assessments of marine litter were conducted as part of the OSPAR Quality Status Report 2023. The revised assessment of seafloor litter was incorporated into this indicator as part of the 2023 update.
The Centre for Environment, Fisheries and Aquaculture Science (Cefas) are currently developing indicator methods for microplastics in marine sediment and biota, which will be incorporated in a future update to the Outcome Indicator Framework.
Indicator components
Figure C1a: Items of litter per 100m of beach, England, 2017 to 2022
Table C1a: Items of litter per 100m of beach, England, 2017 to 2022
| Date | Location code | Lower ci values | Observed values | Smoothed values | Upper ci values |
|---|---|---|---|---|---|
| 2016-12-03 | UK049 | 539.01 | 36.00 | 1,256.66 | 1,974.32 |
| 2016-12-18 | UK043 | 581.58 | 1,031.00 | 1,261.39 | 1,941.20 |
| 2017-01-14 | UK050 | 652.97 | 3,903.00 | 1,268.87 | 1,884.76 |
| 2017-01-15 | UK020 | 655.48 | 1,375.00 | 1,269.12 | 1,882.75 |
| 2017-01-20 | UK048 | 667.88 | 51.00 | 1,270.34 | 1,872.79 |
| 2017-04-02 | UK043 | 816.51 | 1,826.00 | 1,281.64 | 1,746.77 |
| 2017-04-03 | UK048 | 818.15 | 211.00 | 1,281.71 | 1,745.27 |
| 2017-04-08 | UK050 | 826.17 | 2,614.00 | 1,282.00 | 1,737.83 |
| 2017-04-09 | UK020 | 827.74 | 1,854.00 | 1,282.05 | 1,736.36 |
| 2017-06-10 | UK049 | 900.02 | 105.00 | 1,279.51 | 1,659.00 |
| 2017-06-12 | UK048 | 901.52 | 35.00 | 1,279.23 | 1,656.93 |
| 2017-06-18 | UK043 | 905.71 | 874.00 | 1,278.31 | 1,650.91 |
| 2017-07-08 | UK050 | 916.42 | 2,500.00 | 1,274.44 | 1,632.47 |
| 2017-07-09 | UK020 | 916.83 | 737.00 | 1,274.22 | 1,631.61 |
| 2017-09-16 | UK020 | 918.60 | 1,150.00 | 1,252.18 | 1,585.75 |
| 2017-09-16 | UK049 | 918.60 | 72.00 | 1,252.18 | 1,585.75 |
| 2017-09-16 | UK050 | 918.60 | 734.00 | 1,252.18 | 1,585.75 |
| 2017-09-17 | UK043 | 918.29 | 2,619.00 | 1,251.77 | 1,585.25 |
| 2017-10-13 | UK048 | 907.60 | 9.00 | 1,240.49 | 1,573.39 |
| 2017-12-16 | UK050 | 864.96 | 2,112.00 | 1,207.55 | 1,550.15 |
| 2017-12-17 | UK043 | 864.16 | 1,129.00 | 1,206.99 | 1,549.82 |
| 2018-01-14 | UK020 | 841.05 | 6,867.00 | 1,190.77 | 1,540.48 |
| 2018-01-15 | UK048 | 840.20 | 23.00 | 1,190.17 | 1,540.14 |
| 2018-02-24 | UK049 | 804.06 | 218.00 | 1,163.29 | 1,522.52 |
| 2018-04-13 | UK048 | 757.11 | 0.00 | 1,125.08 | 1,493.04 |
| 2018-04-14 | UK050 | 756.11 | 999.00 | 1,124.23 | 1,492.36 |
| 2018-04-15 | UK020 | 755.11 | 1,518.00 | 1,123.39 | 1,491.67 |
| 2018-04-21 | UK049 | 749.09 | 150.00 | 1,118.29 | 1,487.49 |
| 2018-04-22 | UK043 | 748.09 | 3,387.00 | 1,117.43 | 1,486.78 |
| 2018-06-03 | UK049 | 706.26 | 287.00 | 1,080.81 | 1,455.36 |
| 2018-06-17 | UK043 | 692.80 | 1,916.00 | 1,068.51 | 1,444.22 |
| 2018-06-22 | UK048 | 688.10 | 73.00 | 1,064.13 | 1,440.17 |
| 2018-06-26 | UK020 | 684.38 | 336.00 | 1,060.64 | 1,436.91 |
| 2018-06-30 | UK050 | 680.69 | 580.00 | 1,057.10 | 1,433.52 |
| 2018-09-15 | UK020 | 606.38 | 630.00 | 972.45 | 1,338.51 |
| 2018-09-15 | UK043 | 606.38 | 1,408.00 | 972.45 | 1,338.51 |
| 2018-09-15 | UK049 | 606.38 | 654.00 | 972.45 | 1,338.51 |
| 2018-09-15 | UK050 | 606.38 | 1,894.00 | 972.45 | 1,338.51 |
| 2018-12-16 | UK043 | 486.57 | 1,930.00 | 848.70 | 1,210.83 |
| 2019-01-13 | UK020 | 443.44 | 286.00 | 810.76 | 1,178.07 |
| 2019-01-26 | UK049 | 423.37 | 369.00 | 793.59 | 1,163.81 |
| 2019-02-15 | UK048 | 393.34 | 14.00 | 768.01 | 1,142.68 |
| 2019-04-07 | UK020 | 328.77 | 538.00 | 709.48 | 1,090.18 |
| 2019-04-13 | UK049 | 322.59 | 115.00 | 703.18 | 1,083.76 |
| 2019-04-15 | UK048 | 320.49 | 14.00 | 701.02 | 1,081.55 |
| 2019-04-20 | UK050 | 315.13 | 292.00 | 695.52 | 1,075.90 |
| 2019-06-22 | UK049 | 233.46 | 1,281.00 | 617.53 | 1,001.59 |
| 2019-07-06 | UK050 | 212.03 | 292.00 | 599.59 | 987.16 |
| 2019-07-07 | UK043 | 210.47 | 1,310.00 | 598.32 | 986.18 |
| 2019-07-14 | UK020 | 199.52 | 410.00 | 589.51 | 979.50 |
| 2019-09-18 | UK048 | 108.01 | 1,376.00 | 518.61 | 929.20 |
| 2019-09-20 | UK043 | 106.10 | 1,279.00 | 516.98 | 927.87 |
| 2019-09-21 | UK020 | 105.17 | 981.00 | 516.19 | 927.20 |
| 2019-09-21 | UK049 | 105.17 | 322.00 | 516.19 | 927.20 |
| 2019-09-21 | UK050 | 105.17 | 620.00 | 516.19 | 927.20 |
| 2019-12-14 | UK049 | 44.13 | 414.00 | 460.99 | 877.86 |
| 2019-12-15 | UK043 | 43.58 | 374.00 | 460.46 | 877.35 |
| 2020-01-05 | UK020 | 32.63 | 330.00 | 449.97 | 867.30 |
| 2020-01-25 | UK050 | 23.38 | 288.00 | 441.05 | 858.72 |
| 2020-02-25 | UK048 | 10.86 | 53.00 | 429.17 | 847.48 |
| 2020-09-19 | UK020 | -50.64 | 471.00 | 395.12 | 840.88 |
| 2020-09-20 | UK043 | -50.90 | 306.00 | 395.09 | 841.07 |
| 2020-09-20 | UK050 | -50.90 | 155.00 | 395.09 | 841.07 |
| 2020-12-11 | UK049 | -69.18 | 53.00 | 394.24 | 857.67 |
| 2021-06-28 | UK049 | -59.18 | 536.00 | 388.80 | 836.79 |
| 2021-07-11 | UK020 | -55.08 | 249.00 | 387.48 | 830.04 |
| 2021-09-18 | UK020 | -32.21 | 1,004.00 | 382.46 | 797.14 |
| 2021-09-18 | UK050 | -32.21 | 660.00 | 382.46 | 797.14 |
| 2021-09-21 | UK048 | -31.23 | 734.50 | 382.31 | 795.86 |
| 2021-09-23 | UK049 | -30.59 | 124.00 | 382.22 | 795.02 |
| 2021-12-12 | UK043 | -10.04 | 901.00 | 379.79 | 769.61 |
| 2022-01-07 | UK049 | -7.42 | 137.00 | 379.47 | 766.35 |
| 2022-01-09 | UK020 | -7.34 | 371.00 | 379.45 | 766.24 |
| 2022-04-02 | UK050 | -26.04 | 781.00 | 379.09 | 784.21 |
| 2022-04-03 | UK043 | -26.58 | 318.00 | 379.08 | 784.75 |
| 2022-04-03 | UK048 | -26.58 | 59.00 | 379.08 | 784.75 |
| 2022-04-06 | UK049 | -28.25 | 134.00 | 379.07 | 786.40 |
| 2022-04-10 | UK020 | -30.61 | 541.00 | 379.06 | 788.73 |
| 2022-06-19 | UK048 | -95.80 | 40.00 | 378.86 | 853.51 |
| 2022-07-08 | UK049 | -121.28 | 198.00 | 378.90 | 879.07 |
| 2022-07-10 | UK020 | -124.15 | 441.00 | 378.91 | 881.96 |
| 2022-09-17 | UK020 | -242.77 | 690.00 | 379.88 | 1,002.53 |
| 2022-09-18 | UK043 | -244.74 | 554.00 | 379.91 | 1,004.56 |
| 2022-09-18 | UK048 | -244.74 | 335.00 | 379.91 | 1,004.56 |
| 2022-09-24 | UK050 | -256.74 | 203.50 | 380.07 | 1,016.89 |
| 2022-10-06 | UK049 | -281.43 | 132.00 | 380.45 | 1,042.33 |
Trend description for C1a
The individual survey results show that the number of litter items per 100 metres of beach in England varies considerably, from a maximum of 6,900 items in January 2018 to a minimum of zero items in April 2018. Therefore, a LOESS smoother has been applied to view trends in the data. The smoothed values peak in April 2017 at 1,280 items per 100 metres. The trend shows an overall decline between this date and September 2021 to 380 items per 100 metres, where it remains until the end of the series, October 2022.
Assessment of change
The assessment presented here is taken from the source publication for this indicator component. A Theil-Sen slope estimation was used, as this method is robust to outliers, which are common in beach litter data. It was not considered appropriate to assign a percentage change using this methodology. A statistically significant decrease (or improvement) of 103.6 litter items per 100 metres per year was observed over the short-term time period (2017 to 2022). This assessment does not consider whether any improvement is on a sufficient scale for meeting targets.
Change since 2018 has not been assessed, however this will be considered for future updates to this indicator.
The assessment results reported here may not be directly comparable with other analyses published elsewhere that use different methodologies to explore these indicators or are based on alternative datasets.
Further information on the standard assessment used in the Outcome Indicator Framework, along with details on the methodology, is provided in the Assessment background page. Summaries by 25 Year Environment Plan goal and information on indicator links are presented in the Assessment results.
Table C1a: Assessment of change
| Component | Subcomponent | Period | Date range | Percentage change | Smoothing function | Assessment of change |
|---|---|---|---|---|---|---|
| C1a | Observed values | Short term | 2017 to 2022 | N/A | Theil-Sen slope estimation | Improvement |
| C1a | Observed values | Medium term | N/A | N/A | N/A | Not assessed |
| C1a | Observed values | Long term | N/A | N/A | N/A | Not assessed |
Figure C1b: Percentage of sampled fulmars having more than 0.1 g of plastic in their stomach, Greater North Sea, 2004-2008 to 2019-2023
Table C1b: Percentage of sampled fulmars having more than 0.1 g of plastic in their stomach, Greater North Sea, 2004-2008 to 2019-2023
| Time period | Percentage |
|---|---|
| 2004-2008 | 62 |
| 2005-2009 | 65 |
| 2006-2010 | 64 |
| 2007-2011 | 64 |
| 2008-2012 | 64 |
| 2009-2013 | 61 |
| 2010-2014 | 62 |
| 2011-2015 | 66 |
| 2012-2016 | 57 |
| 2013-2017 | 53 |
| 2014-2018 | 48 |
| 2015-2019 | 47 |
| 2016-2020 | 44 |
| 2017-2021 | 44 |
| 2018-2022 | 43 |
| 2019-2023 | 37 |
Trend description for C1b
The percentage of surveyed (beached) fulmars in the Greater North Sea region which were found to have more than 0.1 g of plastic in their stomachs decreased from a peak of 66% in the 2011-2015 survey period to 37% in the 2019-2023 survey period. This measure reflects the abundance of floating litter in their environment, with 0.1 g being the threshold level used in the OSPAR target definition.
Assessment of change
A decrease (or improvement) in the percentage of sampled fulmars which have more than 0.1 g of plastic in their stomach was observed over the short-, medium-, and long-term time periods. This assessment does not consider whether any improvement is on a sufficient scale for meeting targets.
Change since 2018 has also been assessed. A decrease (improvement) in the fulmar indicator was observed since 2018.
The assessment results reported here are not directly comparable with other analyses published elsewhere that use different methodologies to explore these indicators or are based on alternative datasets.
Further information on this assessment, along with details on the methodology, is provided in the Assessment background. Summaries by 25 Year Environment Plan goal and information on indicator links are presented in the Assessment results.
Table C1b: Assessment of change
| Component | Period | Date range | Percentage change | Smoothing function | Assessment of change |
|---|---|---|---|---|---|
| C1b | Short term | 2014-2018 to 2019-2023 | -22.92 | Rolling average | Improvement |
| C1b | Medium term | 2009-2013 to 2019-2023 | -39.34 | Rolling average | Improvement |
| C1b | Long term | 2004-2008 to 2019-2023 | -40.32 | Rolling average | Improvement |
Percentage change refers to the difference seen from the first to last 5-year moving average in the specified date range.
Figure C1c: Mean probability that benthic trawl surveys contain a litter item, expressed as a percentage, Greater North Sea and Celtic Seas, 2012 to 2019
Table C1c: Mean probability that benthic trawl surveys contain a litter item, expressed as a percentage, Greater North Sea and Celtic Seas, 2012 to 2019
| Year | Celtic Seas | Greater North Sea |
|---|---|---|
| 2012 | 47.00 | 57.00 |
| 2013 | 49.00 | 67.00 |
| 2014 | 53.00 | 69.00 |
| 2015 | 43.00 | 59.00 |
| 2016 | 38.00 | 69.00 |
| 2017 | 40.00 | 76.00 |
| 2018 | 45.00 | 73.00 |
| 2019 | 43.00 | 75.00 |
Trend description for C1c
In the Greater North Sea, there has been a gradual increase in the mean probability of a benthic survey containing litter, from 57% in 2012 to 75% in 2019. In the Celtic Seas, the mean probability of a survey containing litter has fluctuated around 45%, with a peak of 53% in 2014.
Assessment of change
The time series for C1c, mean probability that benthic trawl surveys contain a litter item, is from 2012 to 2019 which is not yet long enough to produce an assessment for the medium- and long-term time periods.
An increase (or deterioration) was observed in the Greater North Sea region, but a decrease (or improvement) was observed in the Celtic Seas region over the most recent 5 years for which trends can be assessed (2014 to 2019). However, it is important to note that assessment results reported here are based on smoothed data, and are not directly comparable with other analyses published elsewhere that use different methodologies to explore these indicators or are based on alternative datasets.
Further information on this assessment, along with details on the methodology, is provided in the Assessment background. Summaries by 25 Year Environment Plan goal and information on indicator links are presented in the Assessment results.
Table C1c: Assessment of change
| Component | Subcomponent | Period | Date range | Percentage change | Smoothing function | Assessment of change |
|---|---|---|---|---|---|---|
| C1c | Celtic Seas | Short term | 2014 to 2019 | -12.64 | Loess | Improvement |
| C1c | Celtic Seas | Medium term | N/A | N/A | N/A | Not assessed |
| C1c | Celtic Seas | Long term | N/A | N/A | N/A | Not assessed |
| C1c | Greater North Sea | Short term | 2014 to 2019 | 11.93 | Loess | Deterioration |
| C1c | Greater North Sea | Medium term | N/A | N/A | N/A | Not assessed |
| C1c | Greater North Sea | Long term | N/A | N/A | N/A | Not assessed |
Assessment categories for indicator C1c were assigned based on smoothed data, so percent change figures in Table C1c may differ from unsmoothed values quoted elsewhere. Percentage change refers to the difference seen from the first to last year.