1. Introduc­tion

Seaweed cultivation is a developing aquaculture in Europe, and is expected to grow considerably by 2030 (e.g., Vance et al. (2023).

Seaweed aquaculture has been suggested to facilitate a number of ecosystem services such as nutrient and carbon dioxide uptake, oxygen production, and stimulation of biodiversity (Duarte et al., 2017) and is in addition projected to advance across a range of the United Nations Sustainable Development Goals (Duarte, Bruhn and Krause-Jensen, 2022). To safeguard and guide the development of the seaweed aquaculture towards sustainable development some studies have been conducted on potential risks and negative effects of seaweed aquaculture (e.g., (Campbell et al., 2019; Hancke et al., 2021). With significant upscaling of seaweed aquaculture, small effects, both positive and negative, could have important implications. The United Nations Environment Programme (UNEP) acknowledges the potential of seaweed cultivation and has recently published a report that critically examines the potential to sustainably expand seaweed aquaculture with minimal environmental and social risks (United Nations Environment Programme, 2023).

The overall aim of this report is to provide an overview of the most relevant environmental effects and potential impacts related to seaweed cultivation and its activities in the Faroe Islands (Chapter 1.2). The current seaweed cultivation activities in the Faroe Islands are described (Chapter 1.1) for assessing the potential impacts on the marine environment (Chapter 3). Assessment of the environmental impacts related to seaweed aquaculture in the Faroe Islands, will be based on standard Environmental Impact Assessment (EIA) principles.

In the Faroe Islands, there is currently an area of 2.3 km² (230 ha), that is licenced to seaweed aquaculture. The cultivation areas are located in Kaldbaksfjørður, Funningsfjørður and Gøtuvík (á Norði et al., 2023) and are in sizes from 27 to 153 ha. There are licenses to produce three brown algal species; Alaria esculenta, Laminaria digitata and Saccharina latissima, and two red algal species; Palmaria palmata and Porphyra umbilicalis.

As in Europe, the seaweed aquaculture in the Faroe Islands has the potential to expand and the area demand for seaweed cultivation in the Faroe Islands thus will increase correspondingly.

Production practices are important for the potential environmental impact. At this early stage in the development of the Faroe Island seaweed aquaculture there are no proven methods (best practices) and the authorities have not yet specified methodical requirements.

Most commonly, the production cycle starts with fertile sporophytes also called mother plants (see Table 1). The fertile sporophytes can be picked from natural populations or from a sea farm production. Most producers harvest their farm’s biomass before the produced sporophytes become fertile, but the immature sporophytes of some of the species can be harvested and sporogenesis can be induced in the hatchery by a method where the transport of sporulation inhibitors is blocked (Pang and Lüning, 2004). The sporogenesis method has occasionally been used in the Faroese seaweed aquaculture.

Depending on the seeding method, the need for mother plants varies. Seeding with spores requires a higher number of mother plants than seeding with sporophyte culture. When seeding spores from A. esculenta or S. latissima onto twine or rope, the farmer would need approximately 5 to 10 kg fresh weight of mother plants to produce spores enough to seed 1000 m of rope. Only a few mother plant individuals would be enough when seeding with sporophyte cultures because the density of the dormant or hibernating cultures can be increased.

To minimise the potential genetic impact from the sea farm to the natural seaweed population in the area surrounding the sea farm, it is important to collect mother plants from local populations to produce spores for farming. This precaution is generally demanded by Norwegian authorities for cultivation in Norway (Fredriksen and Sjøtun, 2015; Hancke et al., 2021). Another important factor is to harvest the biomass on the sea farm before the seaweed individuals become fertile. 

Seeding with spores on twine or rope and providing the seeded material a hatchery period of ca. 6 weeks before deployment on the sea farm was found to give the best biomass yield and frond length results in S. latissima (Forbord et al., 2020). The poorest results were observed when the ropes were seeded directly with sporophyte culture and deployed without a hatchery period after seeding (Forbord et al., 2020). Direct seeding with deployment right after seeding can increase the genetic impact on the surrounding natural seaweed populations because the seeded sporophytes are not well attached to the rope and are easily washed off.  Developing the seeded twine or rope in the hatchery demands space and a pumping and cleaning system of seawater and a water treatment before discharge. Hatchery facilities are expensive to obtain and the hatchery is also energy demanding to run, however, a well-functioning hatchery is probably a good investment in the long run.

Biofouling, especially of fast-growing diatoms can be very difficult to avoid. Some level of biofouling is acceptable in the tanks with developing sporophytes on twine or rope but in free floating gametophyte and sporophyte cultures, diatoms can be controlled at a low level with adding germanium dioxide (GeO₂) to the culture solution. Addition of nutrients is often required when developing a healthy sporophyte culture. In a hatchery with a flow through system of seawater and sporophytes developing on twine or ropes in tanks, additional nutrients are not required. 

The deployment period of seeded ropes in the Faroe Islands is usually from October to January, and harvest of food grade biomass is from May to June. In late June and through the summer, there is a significant increase in biofouling on the seaweed biomass (Koester, 2022) and therefore a decrease in quality. It is, however, possible to use an alternative harvesting method called partial harvest or multiple partial harvest (Bak, Mols-Mortensen and Gregersen, 2018). The method makes it possible to seed a rope once and harvest two or multiple times. The method has been found to work well for S. latissima in the Faroe Island, however, leading to different quality grades of biomass. Koester (2022) found that the re-growth in A. esculenta, cultivated in the Faroe Islands, was limited after the first partial harvest in June and that the quality of the crop was compromised by biofouling before the second harvest in August.

As such, the potential environmental impact from a sea-based seaweed farm depends on the farming practices. A farm that is deployed in October and harvested in June will likely have a different environmental impact compared to a farm that carries biomass year-round.

To improve environmental management and minimise the impact from cultivation of seaweeds and its related activities, an Environmental Impact Assessment (EIA) must be performed.

EIA principles are generally described as being a process to avoid, prevent or reduce adverse environmental consequences of human activities, in this case, seaweed cultivation and its associated activities. If adverse environmental impacts cannot be fully avoided, measures should be considered to reduce and control such impacts within established limits or criteria.

An EIA describes all activities with expected significant impacts, in this case, the seeding activities and on-grow in sea. Further, the EIA includes potential impacts and how they can be mitigated. In EIAs, this is typically followed up by a monitoring programme for assessing the efficiency of mitigation measures and being able to identify potential (unexpected) effects or changes to natural conditions and ecosystems, and adjust activities and mitigation measures accordingly (feedback monitoring). To be able to detect potential changes and impact on the environment, the natural status and background information of the environment must be measured and mapped. As such, sufficient knowledge about the environmental baseline (i.e., the biochemical and ecological status as well as ecosystem functioning prior to seaweed cultivation) needs to be established and presented in the EIA.

An initial site survey to establish an environmental baseline is needed to identify environmental impacts from an activity or construction (including buildings and other infrastructure). Site surveys should include data on biotic and abiotic conditions, i.e., biological, environmental, physical, and ambient conditions; and thus information, which are relevant to all types of impact from seaweed cultivation operations.

Hence, through a site survey, a baseline is established based on compiled information such as:

From baseline information, as mentioned above, collected through fieldwork and designed sampling, impacts from activities or infrastructure can be assessed and modelled, e.g., by measuring and modelling nutrient cycling from coastal hydrography, changes in oxygen levels and light attenuation, mapping of seabed communities and presence of sensitive species, their breeding and moulting seasons. In addition, focus on assessment of unintended dispersal of harmful diseases and gene pools is relevant.

The potential environmental impacts relevant to cultivation of seaweed species in the Faroe Island are listed in Table 1, based on the actual described cultivation activities (Chapter 1.1), compilation of the KELPPRO project’s results (Chapter 2) as well as potential impacts treated in the literature (Hancke et al., 2018; Campbell et al., 2019; Visch et al., 2020; Armoskaite et al., 2021; Norderhaug et al., 2021).

Please note, that due to presently relatively small-scale activities, and no factories as such are (yet) established, the EIA components only include cultivation activities, that is from hatchery seeding activities to harvest including potential loss of biomass during harvest, but do not include downstream activity components. This means that in the present EIA scoping, no downstream activities such as, e.g., emissions and discharges from factories (e.g., drying and packing processes), and waste management (e.g., lines and waste biomass on lines are included). Further, no visual or social impacts are included in the present scope of EIA.

Table 1. Overview of potential environmental impacts from cultivation of seaweed and related activities, as described in Chapter 1.2.1, and references. The list is developed with Campbell et al., (2019, fig. 2) as basis, and amended according to KELPPRO (Chapter 2), relevant literature, and input from the project workshop (á Norði et al., 2023). As an addition, the list includes emission and discharges.

*DOM = Dissolved Organic Matter, POM = Particulate Organic Matter.

The potential impacts listed and described in Table 1 will be assessed in detail for relevance and significance for seaweed cultivation in the Faroe Islands for scoping the EIA in Chapter 3. From this basis a baseline programme (Chapter 1) and a proposed implementation plan (Chapter 1) is outlined. A monitoring plan is only touched upon and is expected to be developed as a phase 2 of the present project (Chapter 1).

Mitigation measures are initiatives that seek to reduce the environmental impacts of an activity, e.g., mooring methodology, timing of on-grow in sea, seawater management, etc. Mitigation measures should be identified for all significant impacts of seaweed cultivation flow scheme, and should be included in the EIA. Thus, mitigation measures can be behavioural adjustments (timing, speed), technical solutions (biodegradable mooring devices), design solutions (cultivation line spacing) or resource management (e.g., energy, water). To assess the applicability and efficiency of potential mitigation measures, knowledge about new environmentally friendly technologies, available standards and best practices must be continuously updated to have state-of-the-art mitigating measures in place. In general, the best available techniques (BAT) and best environmental practice, e.g., according to OSPAR (OSlo-PARis Conventions), should be followed and applied.

As part of the EIA and identified mitigation measures, a plan for monitoring impacts is developed to assess that the activities do not have any unexpected effects as well as to evaluate if the mitigation measures have the desired effect and environmental aims and targets are being met. Hence, an environmental impact monitoring plan describes which parameters are to be monitored and how, in accordance with the established baseline. This can include monitoring of, e.g., period of time for activities at sea, use of seawater, seawater nutrient levels, and loss of seaweed material to the seabed.

The current legislative framework on aquaculture for the Faroe Islands was adopted in 2003 and has been focused on salmon aquaculture with the objective to promote a profitability and competitiveness in aquaculture within a sustainable framework. The Aquaculture act (2009) is the general and coordinating law and stipulates the concept of one farming licence per management area, typically on the scale of fjords. This concept was changed to allow farming licences issued for low trophic species assuming that low trophic aquaculture pose no risk to the fish farming activity in the management area. This was done in the Aquaculture Licensing Regulation (2019) which allowed for multiple species in six management areas (Kaldbaksfjørð, Eystan fyri Nólsoynna, Gøtuvík, Skálafjørð, Funningsfjørð, and Fámjin) (ICES, 2023; á Norði et al., 2023). As mentioned in Chapter 1.1 the first seaweed cultivation licences were issued in 2020. Even though the Aquaculture Act refers to the Environmental Protection Act (1988), based on which an environmental permit is required (issued by the Faroese Environment Agency, FAE) to have a farming licence issued (by the Faroese Food and Veterinary Agency, FFVA), the newly issued seaweed cultivation licences do not have an environmental permit. This is due to the fact that currently there is no specific regulatory regime comprising seaweed cultivation with regards to environmental management and thus it is regulated by general rules in the Aquaculture Act (2009) and the Marine Environmental Protection Act (2005) including requirements of EIAs (á Norði et al., 2023).

In May of this year the new Nature Protection Act (2024) was passed and will be enacted on January 1st 2024. The objective with the act is to protect biodiversity and the ecological processes in nature, both for nature itself and for nature as the foundation for sustainable activities, resources, culture, health, and well-being of the Faroese people now and in the future. The Nature Protection Act is a framework law and still has to be implemented through regulations, and as such will take some time to be realised.

Present work thus comes at an opportune time, while still at the beginning phases of a seaweed cultivation industry in the Faroe Islands, to both guide necessary changes in the current Environmental Protection Act and to prioritise development of necessary regulation in the new Nature Protection Act to accommodate a sustainable seaweed cultivation industry.