In February, Working Group 43 of the UN Scientific Expert Committee (GESAMP) presented the second sub-report on marine litter from sea-based sources.

The working group has documented that marine litter from sea-based sources is a significant source of the total volume of plastic in the sea, with serious environmental consequences; with the special additional challenge of ALDFG (Abandoned, lost or otherwise discarded fishing gear) on fauna both on land and in the sea.

The sub-report is from ongoing work and is not the final report from GESAMP.

Partially good regional data – a need for better global data

The ambition of the working group is to adopt a global perspective, although the work has revealed significant geographical variations and insufficient data for several of the identified sources. Robust and credible data are important as a basis for the prioritisation of measures and a unified understanding of reality. The working group notes that both the much used distribution between land-based and sea-based sources of 80% versus 20%, and the statement “640,000 tonnes of fisheries equipment becomes marine litter every year”, cannot be attributed to any source of scientific or grey literature. Thus, the working group will continue to focus on providing a better data basis (quantity, type of waste and ALDFG hotspots) and a global estimate. The working group is also clear that a lack of global estimates should not prevent action on a local and regional level.

There is a lack of fisheries data on marine litter from recreational fishing

The report summarises waste from the global fisheries industry from both small and large entities and has also looked at recreational fishing. The report contains an overview of plastic components used in different types of gear also describing operational characteristics. The focus of the report is on how different factors interact and how they can affect the likelihood of loss and the propensity for abandon/intentially discard fishing gear in the sea. Not only does this apply to physical factors or types of gear. The report also describes how the fisherman’s knowledge and overall fishing experience can prevent loss.

The first effort to statistically to quantify a global estimate was recently completed (Richardson et al. 2019a), the authors estimated that 5.7% of all fishing nets, 8.6% of all pots and 29% of all fishing lines are lost to the sea annually. Data are missing from Africa, Antarctica, Asia and South America regarding the loss of fisheries equipment.

Estimates from recreational fishing are not available, and this is problematic when this source of ALDFG has also been identified by relevant authorities in many parts of the world.

Aquaculture – critical lack of data in a global growth industry

Aquaculture has become an industry in over 200 countries and close to 50% of seafood today is derived from aquaculture. Marine litter is the result wear and tear of plastic gear, loss in connection with incidents and extreme weather, as well as inadequate waste management. The report refers to both the lack of global estimates and non-existent reports of abandoned, lost or dumped plastic from farming in the majority of the countries involved. In light of the strong growth in the industry, the expert group regards it as crucial to address this issue in further research and in its work.

Shipping and other boat traffic – beach cleaning shows an increased volume of waste from commercial shipping

Growth has been witnessed in both the merchant and cruise fleets. The report also describes different types of waste, sources and causes. Some types of waste are easy to link to a source, while other types of waste can be difficult to distinguish from land-based waste. This can be partially remedied by seeing the relationship between several findings in the same area, while also including the location, activity and wear and tear in the analysis. Also in this area, the report shows that there is minimal direct data to enable optimal quantity calculations, and theoretical models engender considerable uncertainty. Improvements have been registered for waste delivered in European ports as a result of the Ship Waste Directive ((EU) 2019/883) from 2019, but there is still a gap between the expected amount of waste and the amount of waste that is delivered. The report also states that it would be useful to have better modelling tools for evaluating when, how and why litter occurs from different categories of vessels. This will also contribute to better quantity estimates and highlight areas exposed to accumulation of waste from shipping. Microplastics from ship-bottom paint and tank cleaning are also included in the report.

Other sources

Fisheries, aquaculture and shipping are the most well-known and described sources of marine litter from sea-based sources. The report also reviews the dumping of waste, both regulated and illegal. In terms of volume and mass, dredging sediments are the largest source. The greatest challenge is that many countries, some of them highly industrialised, are not linked to the London Convention. Thus, they are not included in the global reporting system and the extent of dumping is therefore unknown.

The report calls for quantification of and greater insight into marine litter from offshore activity. There are some data from the North Sea, but these are not necessarily transferable to other geographical areas due to differences in production material and the use of chemicals.

The way forward for the work

Thus far, the work has resulted in a source-based overview with a cause and consequence description. The sub-report describes 24 data and knowledge gaps. Approval has been granted to continue the work on the report:

  • The working group continues to explore and improve itsfindings. The purpose is to arrive at a scientifically based estimate of the relative contribution of sea-based sources to marine litter
  • Analyse in more detail the quantity and plastic material produced and used by the fishing and shipping industry
  • Identify ALDFG hotspots
  • Continue the work to further quantify the environmental, social and economic impact of ALDFG
  • Review and compare options to reduce the problem of sea-based sources of marine litter.