Til innholdet




Prosjektnummer: 901820
Status: Pågår
Startdato: 01.02.2023
Sluttdato: 31.03.2025

Surveying microplastic release from aquaculture nets and ropes using different technologies for emission reduction (SMARTER)

Microplastic (MP; <5 mm) is a ubiquitous marine pollutant, being found in all environmental compartments from the tropics to the poles. Available data suggest MPs and the chemicals associated with them may cause a range of toxicological effects in marine organisms and humans. A significant proportion of MP derives from direct emissions related to anthropogenic activity in the marine space. Plastic used within the aquaculture industry may be an important source of MP pollution, as well as a source of product contamination. With a significant proportion of the produce from aquaculture consumed by humans, it is important to look at ways of minimizing MP emissions.
Among the possible sources of MP release from aquaculture, nets are thought to one of the most significant. Nets make up approximately 75% of all submerged surfaces at a farm site. Traditionally, they are made of nylon multi-filaments, although recent developments have led to diversification where HDPE and Dyneema have been used as the main polymer. The nets are often coated to protect from UV degradation, facilitate in-situ cleaning, and reduce abrasion. However, these coatings have a finite lifespan and gradually erode over time, exposing the underlying net material to UV and mechanical/abrasive degradation mechanisms that lead to MP emissions. Other sources of MP emissions from aquaculture include feeding pipes, ropes, and polyethylene pipes found in pen structures such as floating collars and sinker tubes.
Biofouling of aquaculture nets is typically mitigated by regular (i.e. up to weekly) in-situ pressure washing. During this operation, coatings are often damaged and abraded from the net, while the net material itself undergoes wear and tear. As cleaning may be one of the main factors driving the release of MPs from nets, it is important to understand the quantity of emissions at the local and national scales.
New generation washing technologies such as cavitation-based pressure washing and brush-based grooming, which are less abrasive, may to have the potential to reduce the MP release from nets and coatings compared to conventional pressure washing. Further options to reduce MP release include the use of alternative net materials. Abrasion resistance may be increased by applying thicker fibres (for instance HDPE nets), or stronger materials (for instance UHMWPE/Dyneema). In addition, more durable material formulations may provide better resistance to abrasion during washing operations.
Main objective
To assess and model microplastics release from aquaculture structures and to quantify the reduction of MP emissions by introducing feasible measures under relevant environmental conditions.
• To assess the impacts of different net cleaning methods, polymer compositions and coating formulations on the release of MP from aquaculture nets.
• To assess the emission of MPs from ropes and investigate the coating of ropes as a mitigation measure to reduce MP emissions.
• To develop a material flow analysis model for quantifying the scope of MP emissions and identifying the most effective intervention points and mitigation actions.
​Expected project impact
The results and outcomes from SMARTER will allow the aquaculture industry to identify beneficial combinations of net materials, net coatings and net cleaning technologies as well as rope materials and rope coatings that facilitate reduction of MP emissions. By combining the new knowledge generated in SMARTER with existing knowledge from previous and ongoing projects, SMARTER will create a model for MP release that includes the primary plastic-based structures utilized in fish farms (nets, ropes, feeding pipes, moorings, cage collars and sinker tubes). This will ensure that the emission models are as accurate as possible and offer a holistic picture to the aquaculture industry at the end of the project. The inclusion of large national suppliers in SMARTER supports direct dissemination to potential clients, thus exceeding traditional scientific promotion channels.

By providing producers data about their own emissions, mitigation actions can be implemented and provide a strong platform for improved public perception of the aquaculture industry in relation to the issue of MP emissions. As the products and materials tested in SMARTER are commercially available, they can immediately be implemented during routine investment and replacement processes at individual aquaculture farms. The outcomes of SMARTER will therefore enable an immediate reduction of MP emissions from the aquaculture industry.

SMARTER provides the participating companies key market opportunities depending on the outcomes of the project:
• A positive comparison to traditional net and rope materials, coatings, and cleaning approaches that will allow the technologies to be accurately marketed for minimising MP emissions. This could provide a competitive advantage and have a positive impact for the innovative technology companies within the Norwegian and international markets. 
• The project data will provide the companies with a baseline and an secondary opportunity for further product development to reduce MP emissions.
• As MP emissions may directly correlate to the lifetime of materials (i.e. inferior materials leading to higher MP emissions and lower lifetime), MP release data can identify those products with potential for a longer lifetime. This has value to the industry as a whole, as well as reducing environmental contamination and impacts.

In the longer term, it is expected that the emission models to help identify which components of an aquaculture farm are the highest priority for development and implementation of mitigation measures. Moreover, the results from SMARTER will help to serve as an ‘industry baseline’ or benchmark for current MP emissions. This will be an important starting point for assessing the efficacy of future mitigation actions and technologies, as well as for ensuring new materials and technologies entering the market do not lead inadvertently to higher MP emissions.

Finally, emission baseline numbers, as well as the emission models, can provide regulatory bodies and governmental entities with the information platform needed for integration of MP emission limits from aquaculture into laws and regulations.
Project design and implementation
The SMARTER project comprises 3 research-based work packages (WPs). A summary of the general methodologies, the main activities and the milestones associated with each WP are provided here:

WP 1: Assessment of microplastic emission from nets and coatings Responsible: Andy Booth (SINTEF Ocean) Participants: All partners
Quantification and characterization of MP emissions from traditional nets cleaned with traditional pressure washers in comparison to novel net materials, coatings, and cleaning technologies.

T1.1 Lab experiments  Identification of MP emissions from different net materials and coatings
Abrasion testing will be used to quantify and compare abrasion properties, including MP release, of different netting materials and coating types. Tests will be conducted using an abrasion machine designed specifically for nets and ropes (MILA 200 WET, Buraschi Italia).

The test will combine the following factors in a crossed design:
(i) Material: traditional nylon nets will be compared to available alternatives such as different qualities of polyethylene (HDPE, LDPE and Dyneema).
(ii) Coating: uncoated nets will be compared to nets treated with Brynsløkken standard or premium coating.
(iii) Age: the tests will include both new and used nets. Used nets will be taken from fish farms (via existing partner network) and from the field experiments conducted in SMARTER).

Emitted MP will be analysed using a Nile red staining method combined with microscopy and automated particle imaging. A weight comparison of the material will be conducted before and after abrasion testing Results from T1.1 will be used to select two coatings (standard versus premium) for use in the field assessment (T1.2).

T1.2 Net washing experiments T1.1 Lab experiments  Accelerated washing test  
A pen net constructed of individual test panels of different net materials with and without different coatings will be installed in a circular pen at ScaleAQ's test site at Frøya. The pen net design will allow testing of 3 different net types and 2 different coatings (6 different combinations) with each cleaning method (traditional pressure washer, cavitation cleaner and brush-based grooming ROV). The cleaning frequency will reflect expected use for a season at sea and ≥500 L of seawater will be sampled adjacent to the pen during each cleaning process. MP sinking-behaviour will be evaluated using sediment traps deployed for the duration of the cleaning procedure. MP levels, size, shape and polymeric composition will be compared for MP background levels at a selected reference site not affected by aquaculture activities.

T1.3 In-situ sampling       
To assess MP emissions under standard conditions at a farm site, samples will be taken at initial cleaning of nets, as well as at the end of the net's season using traditional pressure washers on different nets. The net type, net area, cleaning conditions and cleaning duration will be documented to allow direct comparison to data from T1.2. This task will provide key data to WP3 for the development of the MP emission model.
T1.4 Service site sampling
T1.4.1 Interviews with the crew of the net service plant will help to map areas of the nets that typically undergo strong abrasion. Samples of used nets will be taken to microscopically assess and document the abrasion, as well as for use in T1.1. Data will be collected from the service station on weight differences of a range of nets after use at sea and abundance of coating needed for re-coating. Existing data from the RobustNet project will be combined with the data from T1.4 and fed into WP3.

T1.4.2 Nets are cleaned in large drum washers at the end of each season, a process that likely generates MPs. There currently exists no knowledge on MPs generated during this process or if they are collected by the filter prior to release. After the washing of pen nets with relevant coatings, water samples from the washer drum will be taken before and after passing the filters. In addition, a sample of a new net with fresh coating will be included in a washing cycle with a regular net. An assessment of the loss of weight of the sample panel will assist in estimating the abrasiveness of the washing process relative to MP emissions during use.

T1.4.3 To assess total material loss over time, nets with an identification tag will be weighed before going to sea, as well as upon return before and after undergoing land-based cleaning. In combination with assessment of abrasion caused by land-based washing, this will provide information on total material lost from a net. The assessment will be linked to the number of net cleaning operations conducted, type of cleaner used etc. 

M4: Net pen comprising the different panels (T1.2) completed and ready for deployment (M5)
M5: Net pen deployed and first sampling under different cleaning conditions completed (M7)
M6: Laboratory studies completed (M12)
M7: In situ sampling completed and data transferred to WP3 (M20)

WP 2: Assessment of microplastic release from ropes
Responsible: Alessio Gomiero (NORCE), Participants: All

Quantification and characterization of MP emissions from (different types of) ropes and assessment of coatings for mitigation. 

T2.1 Lab experiment with ropes of different materials T1.1 Lab experiments  Identification of rope wearing patterns and optimal choice of materials
Abrasion and strain testing will be used to quantify the abrasion properties and the release of MP from ropes. Continuous stretching under photochemical (UV), physical (thermal) stress is expected to induce a significant release of plastic fragments compromising the structure of the ropes and causing a reduction in their performance and reliability over time. As a baseline standard for the industry, PP/polyolefin ropes of 24 mm (3 stranded) and 30 mm (8-braided) will used as the primary comparison point for the other rope materials included in the test. Tests will be conducted using an industry standard abrasion machine designed specifically for nets and roped (MILA 200 WET, produced by Buraschi Italia).

The test will combine the following factors in a crossed design:
(i) Material: widely used PP ropes will be compared to available alternatives, including different qualities of polyethylene and polypropylene (a full selection of ropes will be defined at the start of the project).
(ii) UV exposure: some samples will be exposed to UV light prior to testing.
(iii) Age: the tests will include both new ropes and older ropes collected from fish farms and service stations. 

Sample assessment will consist of (a) quantitative and qualitative characteriation of the MP released into the water and (b) measurement and documentation of the loss of the rope material after abrasion and environmental weathering (UV degradation) by measuring the weight loss. Data from T2.1 feeds into the emission modelling in WP3 as a potential mitigation action. 

T2.2 Lab experiment assessing the reduction of MP using coated ropes
Using knowledge generated in T2.1, a small selection of the highest and lowest MP emitting rope materials will be sent to Brynsløkken for coating in both the standard and premium coatings. These will then be subjected to the abrasion testing as described in T2.1 to identify of the application of the coatings, and which coating might offer a reduction in MP emissions. Data from this T2.2 will also feed into the emission modelling in WP3 as a potential mitigation action.
T2.3 Service site sampling
Interviews with the crew of the net service plant will help to map areas that typically show strong abrasion on used ropes and pen structures. Based on this information, similarly to the nets, samples of used ropes will be taken to microscopically assess and document the abrasion.
M8: A full matrix of ropes selected for abrasion testing identified and sourced (M4)
M9: Coated ropes prepared and sent for testing (M10)

WP 3: Modelling of microplastic emissions
Responsible: Andrea Viken Strand (SINTEF Ocean), Participants: All partners

Set the knowledge gained from testing and interviews into a system context at both the individual farm scale and the national level. Quantifying scope of emissions, most effective points of intervention, and  potential trade-offs of mitigation actions e.g. increased macro plastic waste or increased energy use.
T3.1 Define and visualize relevant system maps
T3.1.1 System mapping must integrate available information with stakeholder understanding of the meaning of the system so that maps can be both accurate and useful. This will involve open communication between all WPs in the project, as well as interviews with workers and management in the partner aquaculture companies. System maps will show system boundaries, processes, and connections at the scale of a single aquaculture farm as well as at the scale of the national sea-based aquaculture industry.

T3.1.2 Based on data and results from WP1 and WP2 as well as literature review, the flows of plastic through the aquaculture sector will be quantified and input to the system maps showing what amounts of MPs are emitted at different points of the production process and where they are lost to.

T3.1.3 Several other projects have generated data on MP emissions from feed pipes and ropes, such as the project ‘Reduction of Microplastic Emission through System Optimisation of Feed Pellet Conveying Pipelines (MICRORED)’ (FHF-901658) and the new project(s) that will be funded by FHF in 2023 that focus on assessment of net cleaning technologies. These findings will be integrated in SMARTER's emission model, so that MP emissions from different sources can be easily compared. 

T3.2 Build dynamic scenario-based model
T3.2.1 A pair of dynamic models of plastics use and losses in aquaculture will be based on the systems that were defined  in T3.1.1. At the single-pen level, the lifetime of a single net or rope will be modelled to show the sensitivity of MP emissions to different system interventions over time. Sensitivities will be calculated statistically showing which current practices and potential mitigation measures have the largest effects. At the national scale, total MP emissions from the coastal Norwegian aquaculture industry will be extrapolated from the quantifications of T3.1.2 modelled over coming decades according to the growth of the industry and the operating practices of the actors.

T3.2.2 Scenarios will model the effects of different MP mitigation technologies and behaviours. Scenarios will be developed based on literature as well as interviews and discussions with actors in the aquaculture industry.
T3.3 Validation of model results
A workshop with interested and knowledgeable stakeholders will be hosted to assess results from the emission model and discuss mitigation options. Knowledge gained in this workshop will be used to update and improve the model as well as results presentation to improve relevance and accessibility of results.
M10:  System definitions and model developed (M6)
M11:  Scenarios Developed and quantified (M12)
M12:  Validation workshop with stakeholders (M18)
M13:  Report on system definitions and model scenario results (M24)
Dissemination of project results
Dissemination and communication of the results and main findings of SMARTER are a key component of the project activities. In addition to the strong track record of the research partners in communicating their science to a broad range of stakeholders and end users, SMARTER also has the NCE Aquatech Cluster formally involved as a 3rd party contractor to support the dissemination activities and create media resources.

A set of media resources will be developed in the early stages of the project, which will comprise a project factsheet, a powerpoint summary slide and an info graphic. The primary mechanism for making information about the project publicly available will be a dedicated project webpage hosted on the SINTEF or NCE Aquatech website. The project will also be profiled on the FHF and NCE Aquatech Cluster webpages, with links to the main project homepage. A webinar will be arranged by NCE Aquatech where the main results and findings will be presented to attendees from NCE Aquatech's extensive network of industry actors and R&D organizations. The in-house journalist from NCE Aquatech will identify stories and interesting results that can be developed into feature articles in trade magazines and towards the national media.