Plastic litter is present in all Hong Kong coastal habitats,
potentially creating severe harm to marine ecosystems

The ground-breaking collaborative Coastal Watch project has been running since June 2014. Developed by WWF and six strategic partner organizations – Eco Marine, Ecovision’s Hong Kong Cleanup, Green Council, Eco-Education and Resources Centre, Ocean Park Conservation Foundation Hong Kong and Plastic Free Seas – the fundamental aim of Coastal Watch is to clean up Hong Kong’s coastlines and trace the sources of marine litter by performing litter and ecological surveys, ultimately helping the government formulate effective long-term solutions to our persistent marine litter problem. It is also hoped that the project will mobilize and educate the public through training “citizen scientist” volunteers, raising public concern about the marine environment and encouraging them to get involved in saving the marine ecology.

Never before in Hong Kong’s history have simultaneous, comprehensive surveys on both the marine ecology and marine litter been conducted across our various coastal habitats. With no such precedent, public understanding of the effects of marine litter on the marine ecology is extremely insufficient. Coastal Watch is the only conservation project in Hong Kong to concurrently conduct marine litter and ecological surveys on seashores, coastal waters and underwater. In the first year of Coastal Watch, a total of 1,125 volunteers conducted surveys in 27 coastal sites of unique ecological value, including mangroves, mudflats, sandy beaches, rocky shores and coral communities, logging 265 survey hours in total. Data from the surveys was collected between July 2014 and May 2015 and classified into five main types: ecological, land-based macro-debris and micro-debris, coastal floating litter and underwater litter.

Hong Kong’s marine habitats have a vast biodiversity

During the ecological surveys, Coastal Watch volunteers and partner organisations recorded species data across various natural coastal habitats. The average number of species recorded in each habitat type was 27 in mangrove environments, 26 in mudflats, 18 in rocky shores and 10 in sandy shores. The mean coral coverage at the underwater sites was 5.5 per cent. These results show that the natural habitats in Hong Kong waters generally contain a vast biodiversity, demonstrating their importance to the ecology.

Plastic content of marine litter exceeds 60% on shorelines

When conducting the marine litter surveys, suitable sampling areas (whether transect lines or belt transects) or a suitable sampling duration needed to be designed, so as to accurately quantify the amount of litter. These designs were dependent on the characteristics of the different habitats. During the land-based macro-debris survey, an average of 391 pieces of marine litter were collected in each five-metre belt transect. In total, plastic constituted 62.3 per cent of the litter from the land-based sites: mangrove, mudflat, sandy beach and rocky shore habitats. The major types of plastic litter collected were plastic fragments and single-use disposable items. During the land-based micro-debris surveys, an average of 131 pieces of marine litter were collected in every one square metre area; plastic constituted 67.4 per cent of this litter. Most of the plastic items found were polystyrene fragments – mainly broken pieces of polystyrene boxes and other packaging. The data also revealed that in both the dry and wet seasons, the marine litter problem at Island House in Tai Po, Little Palm Beach in Sai Kung and Chi Ma Wan on Lantau Island was more serious than at other sites.

First ever investigation of underwater debris in Hong Kong

The floating litter clean-up activities were carried out in collaboration with fishing communities in Hong Kong. During these activities, an average of 695 pieces of marine litter were collected every two hours, and the proportion of plastic was as high as 84.7 per cent. Because of its relatively low density and light weight, plastic litter tends to float on the sea surface. Disposable items such as packaging, bottles, cutlery and polystryrene boxes were the major types of plastic litter collected, with the main origins being domestic and recreational waste, as well as large containers from the city’s markets.

Litter in underwater environments has not been widely studied in Hong Kong. During the Coastal Watch underwater surveys, an average of 58 pieces of marine litter were found along each 100 metre transect. Plastic debris was again the most common material, comprising 60 per cent of all litter encountered. Although there was a relatively higher proportion of higher density and heavier debris such as ceramics and metals found on the sea bottom compared to land-based sites, plastic debris, especially disposable items and abandoned fishing gear, was still ever present.

Plastic debris threatens our marine ecosystem

To summarize the above results, the debris collected in both coastal and marine environments was dominated by plastic. This fact reveals a major problem: plastic litter is posing a serious threat to underwater environments, despite the fact that most members of the public seldom visit these places. There are many coastal sites of high ecological value in Hong Kong, but marine litter is seriously affecting the health of these marine ecosystems. This creates even more urgency – besides responding to public concerns about the hygiene and aesthetic problems of litter, society absolutely must address the marine litter problem from an ecological perspective.

“We have discovered that the natural coasts in Hong Kong all have definitive ecological value, but at the same time these ecosystems all face an enormous threat from plastic litter. During all of the surveys, we observed various organisms entangled in debris which caused injury or death, like “ghost nets” (fishing nets which have been cast adrift). We also found fish bite marks on pieces of plastic litter. The pollutants absorbed by marine animals will potentially bioaccumulate along the food chain, which will eventually damage the marine ecosystem, affect fishery resources and human health. It is imperative that we tackle the marine litter problem at its source immediately.” said Mr Patrick Yeung, Coastal Watch Project Manager.

The Coastal Watch team firmly believes that a joint effort by the government, business and the public is essential to improving the marine litter problem. The government’s Inter-departmental Working Group on Clean Shorelines should extend their focus to cover underwater litter and start to investigate its distribution. This will allow the Working Group to formulate an optimal solution to the marine refuse problem in cooperation with society. Additionally, both consumers and producers should consider the long-term impacts of the use of disposable plastic products on our environment, and should begin to take responsibility for conserving our marine ecosystem. The public should reduce waste at source by using less disposable items, such as polystryrene food containers, disposable utensils, bottled drinks and so on. People should ensure that their rubbish is disposed of properly and responsibly, and actively participate in recycling programmes whenever possible. This will prevent litter from entering the marine environment and harming the marine ecology.

To obtain an even more accurate picture of the marine litter problem around Hong Kong, the second year of the Coastal Watch has expanded the number of project sites to 34. The new sites are Tai O, Shui Hau, Sai Kung Pak Sha Chau, Kuk Po, Siu Lam, Pak Kok and Sham Wan on Lamma Island, and as before, each site has its own unique features. Coastal Watch experts and volunteers will continue conducting ecological and marine litter surveys in all sites, and a comprehensive report on the results of the entire two-year project will be released at the end of 2016.



Coastal Watch 2014 – 2015 Ecological and Marine Litter Survey Result

Survey period:
Jul 2014 – May 2015

Data collected was classified into five main types:

  • Ecological survey
  • Land-based macro-debris survey (sandy beaches, mudflats, mangroves & rocky shores)
  • Land-based micro-debris (sandy beaches, mudflats, mangroves & rocky shores)
  • Coastal floating litter survey
  • Underwater litter survey
  1. Ecological Survey
  •  Average number of species recorded in land-based habitats:

rocky shores:18
sandy beaches:10

  • Coral coverage at the underwater sites: 5.5%
  1.  Marine Litter Survey
  1. Average number of pieces of litter
  Land-based macro-debris(in each five-metre belt transect) Land-based micro-debris(in every one sq. metre belt transect) Coastal floating litter
(collected every two hours)
Underwater litter(along each 100 metre transect)
Average number of pieces 391.4 131.4 694.5 57.9


  1. Composition of Marine Litter
  Land-based macro-debris(in each five-metre belt transect) Land-based micro-debris(in every one sq. metre belt transect) Coastal floating litter(collected every two hours) Underwater litter
(along each 100 metre transect)
Plastics 62.3% 67.4% 84.7% 60.1%
Glasses 20.8% 19.9% 0.5% 8.1%
Metal 3% 0.4% 4.9% 12.6%
Wood 1.5% 3.3% 2.4%
Rubber 0.9% 1.2% 2.1%
Paper 0.6% 1.4% 2.3% 0.2%
Cloth 0.6% 0.3% 0.7%
Others 10.3% 10.9% 2.7% 13.9%
  1. Top Ten Categories of Litter – Land-based macro-debris
Land-based macro-debris  (in each five-metre belt transect)
Rank Categories
1 Glass fragments
2 Polystyrene – fragments
3 Plastic fragments -hard
4 Plastic packaging (wrappers) and film  – fragments
5 Drink bottle caps
6 Thin rope, string, ribbon pieces
7 Cutlery, whole and pieces
8 Plastic packaging (wrappers) and film
9 Other bottle caps, pump and spray lids
10 Plastic fibres – unidentifiable
  1. Top Ten Categories of Litter – Coastal floating litter
Coastal floating litter (collected every two hours)
Rank Categories
1 Plastic packaging (wrappers) and film – fragments
2 Plastic packaging (wrappers) and film
3 Thin rope, string, ribbon pieces
4 Polystyrene – fragments
5 Polystyrene boxes (whole & identifiable pieces)
6 Plastic shopping bags
7 Polystyrene – food boxes & cups (whole & identifiable pieces)
8 Drink bottle caps
9 Drink bottles 1L and less
10 Fast food containers, lids & cups, whole & pieces


  1. Top Ten Categories of Litter – Underwater litter
Underwater litter (along each 100 metre transect)
Rank Categories
1 Ceramics pieces
2 Plastic fragments -hard
3 Plastic packaging (wrappers) and film
4 Drink bottle
5 Metal – other
6 Clear water cups, small, whole & pieces
7 Fishing items (floats, lures, buoys, fishing line)
8 Fishing net pieces
9 Drink bottles 1L and less
10 Glass fragments
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