A new report reveals numerous knowledge gaps concerning possible effects of seaweed harvesting on seabirds and shorebirds in Norway. Stakeholders call for stricter regulations.
The common eider finds food on the sea floor in relatively shallow areas along the coast. Harvesting of knotted wrack takes place in the same areas. Photo credit: Nina Nehnhard/NINA.
There is high commercial interest in harvest of wild brown seaweed internationally and in Norway, being indispensable raw materials in a number of industries, from food production and animal feed to pharmaceuticals and bioenergy.
Despite the increasingly mechanized harvest being practiced since the 1970s, relatively little is known about the effects of harvesting on the ecosystem and especially on seabirds and shorebirds that use these habitats.
Possible disturbance in the breeding season
In Norway, harvest of wild seaweed almost exclusively targets two species, namely tangle (Laminaria hyperborea), growing in the subtidal zone, and knotted wrack (Ascophyllum nodosum), found in the intertidal zone.
Between 2016 and 2023, on average 149 506 tons of kelp and 17 954 tons of knotted wrack were harvested annually. The peak of harvesting for both types of seaweed occurred in the period April-October, which coincides with the migration period and the breeding season of birds.
- We see that the time of harvesting coincides with important periods for seabirds. Kelp trawling can thus disrupt birdlife during the most vulnerable period of the year for seabirds and, in the worst case, affect the supply of food, especially in areas with a large overlap between harvesting areas and bird colonies, says Nina Dehnhard, senior researcher at NINA.
Stakeholders call for stricter regulations
Following a survey of relevant stakeholders, the results revealed skepticism about seaweed and kelp harvesting among various interest groups, including commercial fishermen, industry, NGOs and public administration.
- We were a little surprised by how clear the results from the survey were, says Dehnhard. The majority of respondents, regardless of interest group, were against seaweed and kelp trawling. They expressed a desire for a ban on harvesting in protected areas, and stricter regulation in periods and areas that are important for seabirds and waders.
Need for ecosystem-based management
The report points to several gaps in knowledge about the effects of kelp harvesting on seabirds and waders in Norway. With so little available knowledge, however, it is difficult to provide concrete recommendations as to what sustainable harvesting entails.
- Coastal birds are struggling all over the world. With the nature crisis we are now facing, it is important to manage coastal areas in a way that takes into account both ecosystems and human activity such as seaweed and kelp harvesting, says Dehnhard.
Read the report here (English): Dehnhard, N., Mattisson, J., Christensen-Dalsgaard, S., Junker-Köhler, B., Bargmann, T., Kvalnes, T. 2024. Effects of brown seaweed harvesting on sea- and shorebirds in Norway. Assessment of existing knowledge, spatial overlap and attitudes of interest groups. NINA Report 2502. Norwegian Institute for Nature Research.
Learn more about NINAs seabird research here
Contact: Nina Dehnhard