End-of-life fishing and aquaculture gear: An assessment of the potential recycling capacity in Scotland

Appendix B: SEPA data search method and limitations

Background

In May 2025, Resource Futures (working on behalf of the Marine Directorate, Scottish Government) requested an extract of the waste site returns data to facilitate work they were doing to map infrastructure that might accept EOL fishing and aquaculture gear in Scotland. We (SEPA) were asked to provide data to help identify sites that, according to their waste returns, handle EOL fishing and aquaculture gear. Resource Futures provided a number of key word search terms to facilitate the request. We (SEPA) used these keywords to prepare an extract of the waste inputs data (Table B from the waste site returns), being deemed most appropriate for the purpose. This extract was shared with Resource Futures under the terms of a data sharing agreement.

In September 2025, as follow up, Resource Futures requested a summary of fishing gear waste types managed in Scotland from the waste site returns. This was for the same research commissioned by the Marine Directorate of Scotland on the reprocessing capacity of EOL fishing and aquaculture gear in Scotland.

We (SEPA) conducted a desk-based analysis of the Table B data already provided, to estimate the types and quantities of EOL fishing gear accepted by sites in Scotland for management between 2022 and 2024. We used the same search terms provided by Resource Futures initially. Below is a description of the methodology for the analysis.

Overview

Operators of waste management sites in Scotland authorised by SEPA provide quarterly or annual reports to SEPA on the types and quantities of waste they accept and manage. Operators provide the data in a standard template known as the ‘site return form’. Waste inputs to the site are reported in Table B of the site return form along with an intended management method for each waste type. The data in the site return form are validated and verified by SEPA on a quarterly and annual basis.

For the initial request in May, Table B (inputs) data from the site returns from 2022 to 2024 were used to estimate the types and quantities of potential EOL fishing and aquaculture gear managed in Scotland. This included the number of waste management sites that accepted the wastes and the methods of how the waste was intended to be managed by the site (i.e. treated on-site, sent off-site, or landfilled on-site).

The analysis for the data request in September was also based on Table B data to align with the earlier analysis. As the second analysis was summarising tonnages, a further limited analysis was carried out, focusing on selected sites in the primary analysis, to review Table C4 (waste landfilled after treatment on-site) and Table D (waste outputs) to try and track flows of relevant wastes through the sites. This limited study can only provide indicative results. A fuller analysis of the site returns would be required, along with operator interviews, to provide more definitive results. This was beyond the scope of the request.

The 2022 and 2023 data were fully verified. The 2024 data had been validated but not fully verified at the time of the analyses. In all years, the free-text written descriptions provided by operators and used for keyword searches were unchecked and unverified.

Operators are asked to report waste in the waste site returns using European Waste Catalogue (EWC) codes. A limitation of the analyses was that EWC 02 01 04, for waste plastics (except packaging) can be used for EOL fishing and aquaculture gear plastic^[97] as well as for agricultural waste plastic. In addition, analysis of the data showed that operators had used other EWC codes to report EOL fishing and aquaculture gear. For example, EWC 17 02 13 (for waste plastics), 16 01 22 (for components otherwise not specified), and 02 01 99 (wastes not otherwise specified).^[98] For this reason, we used the operators’ written waste descriptions as well as the EWC codes to search the data with the key words provided by Resource Futures.

Method

All 2022-2024 data with EWC 02 01 04 were extracted and data cleansed by SEPA by reviewing the operator’s written waste descriptions. For all other EWC codes, an in-depth search was carried out by SEPA, using various key terms provided by Resource Futures (Table A). A range in granularity of search terms was provided to cover different levels of detail. These terms were used to search the written waste descriptions provided by operators in Table B of the site returns. Duplicate search results were removed. The search terms are outlined below.

Tier 1 – High level words

Search term

• Harbour
• Net
• Port
• Rope

Tier 2 – Industries and common gear types

Search term

• Aquaculture
• Circle pen
• Crab pot
• Creel
• Fishing
• Fishing pot
• Gill net
• Lobster pot
• Nephrops
• Square pen
• Trawl

Tier 3 – Long list of gear and components

Search term

• Beam trawl
• Buoys
• Demersal trawl
• Dredges
• Fish trap
• Feed pipe
• Floats
• Float line
• Footrope
• Freshwater cage
• Freshwater hatchery
• Freshwater tank
• Headline
• Liner
• Longline
• Mooring netting
• Mooring rope
• Netter
• Otter board
• Oyster bag
• Oyster hanging basket
• Oyster trestle
• Pelagic trawl
• Pen
• Seawater cage
• Seawater hatchery
• Seawater long line
• Seawater raft
• Seawater tank
• Seawater trays
• Seawater trestle
• Seine net
• Sweeps
• Warps

Search results for EWC 02 01 04 - records

The search results for EWC 02 01 04 between 2022 and 2024 produced 65 records across 10 sites. Of these, 48 records were removed during data cleaning as the waste descriptions indicated they were related to agricultural waste. The remaining 17 records were not specified in the descriptions as fishing or aquaculture waste, just being described generally as plastic waste, except for packaging. While these wastes were included in the analysis results, they may not be related to EOL fishing or aquaculture gear. After data cleaning, none of the relevant EWC 02 01 04 records specified ‘marine’, ‘fishing’ or ‘aquaculture’ in the operator waste descriptions (data not shown).

Results for keyword searches of all other EWC codes - records

The keyword search of all other EWC codes between 2022 and 2024 produced 123 records across 13 sites. Of these, 77 records were not relevant and were removed during data cleaning.^[99] This included deleting results where materials were out of scope (e.g. liquids, metals, asbestos or chemicals) or the EWC code indicated it was not relevant (e.g. referred to packaging, liquids, explosives, chemicals and outputs of waste treatment). Seven of the 46 relevant records specified ‘marine’, ‘fishing’ or ‘aquaculture’ in the operator waste descriptions (data not shown).

Search results – all records

The total number of records deemed not relevant after data cleaning highlights the limitation of using EWC codes alone to track EOL fishing and aquaculture gear. Of the 63 relevant records after data cleaning, 8 were associated with treatment onsite (data not shown). Of the 23 sites with relevant records after data cleaning, 6 reported treatments onsite (data not shown).

Limitations

This analysis considered the types and qualities of waste entering waste management sites in Scotland as reported by operators in Table B of the waste site returns. It is hard to comprehensively track the flow of wastes within and between sites using this method due to changing waste codes and descriptions, but an initial (wider) review of the site returns suggested that no relevant wastes were landfilled after treatment onsite (as reported in Table C4 of the site return). It also showed that of the relevant wastes treated onsite or sent offsite, 64 per cent were identifiable as outputs (as reported in Table D of the site return) and almost all of these (98 per cent) stayed in Scotland (data not shown). There could therefore be some double counting, and we may be missing data for relevant wastes that have already passed through a site and changed code or description after treatment (for example if they have been mixed in with other wastes). All findings in this report are heavily caveated without a more in-depth analysis of the site returns, ideally followed up with operator interviews.

After data cleaning there was a limited number of records with ‘marine’, ‘fishing’ or ‘aquaculture’ in the operator waste descriptions. There is therefore a risk that some of the search results are related to non-fishing or aquaculture gear waste. Conversely, the analysis may be missing relevant data due to inconsistent waste descriptions in the general site returns population of data.