Macroalgae are essential components of marine ecosystems. They offer a wide array of essential ecosystem services – significant contributions to global primary production and the efficient absorption of dissolved nutrients from their surroundings. Macroalgae (or seaweeds) play a vital role in coastal protection against erosive forces of wave action and contribute to carbon sequestration. Seaweeds also serve as keystone species that shape habitats in coastal ecosystems. Currently in Europe the utilization of algae is increasing in various commercial sectors. Majority of global macroalgal biomass is derived from cultivation, with an annual production of around 31 million metric tonnes (wet weight). Wild harvesting contributes approximately 1.2 million metric tonnes. In Europe the wild harvesting is providing approx. 0.25 million metric tonnes, accounting for approximately 98% of biomass production.
Macroalgal harvesting presents significant sustainability challenges, particularly as the demand for these resources grows in various industries. While the EU legal instruments emphasize the need for all human activities to be sustainable, there remains a notable gap in knowledge and regulation concerning the sustainable practices of macroalgal harvesting. The report seeks to address this gap by offering recommendations for harmonized monitoring and management approaches, ensuring that macroalgal harvesting (including beach cast collection) aligns with the EU’s sustainability goals and contributes positively to the broader environmental objectives outlined in the Green Deal and related policies.
Several factors are relevant to ensure sustainability of seaweed wild harvesting, in all marine areas, when planning the harvest time and size: geographical distribution of species, various life histories of macroalgae species, recovery potential of each species, scale of created ecological impacts due to seaweed removal, as the level of impact correlates with intensity and frequency of harvesting. Collection of beach cast in most cases should also follow the principles of sustainability, as beach cast serves as part of coastal food webs, except for eutrophic or polluted areas where complete removal could be advised due to leakage of nutrients and pollutants.
Sustainability aspects of seaweed harvesting are included in national regulations of the countries where seaweed is regarded as a valuable resource, mostly on the Atlantic coast (France, UK, Norway). In the Baltic Sea area Estonia is the only country where wild harvesting of industrial size is allowed. Harvesting management systems are founded on a licensing process and involve collaboration between national authorities and fisher organizations, research institutions, and the industry.
Accurate estimates of the seaweed standing stock are prior to any monitoring of wild harvesting and evaluating its sustainability. Monitoring parameters applicable in most cases include characteristics of algae community and basic environmental indices. In the case of beach cast monitoring, concentrations of pollutants are recommended to follow, if the beach cast is intended for use as agricultural fertilizer. Screening for pathogenic microorganisms is suggested in beach cast accumulation areas during the active recreational season.
National policy support could include establishing a link between wild harvesting sites and national MSPs, share a governance of local seaweed resources and try new forms of cooperation for monitoring of harvesting. Joint projects and cost sharing can also reduce the costs of monitoring.
The EU Member States are invited to fill the knowledge gaps on impacts of seaweed wild harvesting and on estimates of beach cast amounts. However, in the future macroalgal cultivation seems more feasible and promising than wild harvesting due to vulnerable habitats of wild seaweed, experiencing stress under projected climate change. Therefore, further investigations focusing on long-term sustainability aspects of large-scale cultivation are of utmost importance.
