Dulse production (WP3)

The aim of work package 3 is to bring dulse production towards a stable production of commercial quantities.

Dulse production in Limfjorden. Photo: DTU Aqua
Dulse production in the Limfjorden. Photo: DTU Aqua.

Background and aim

Cultivation of dulse relies on reliable hatchery techniques as well as optimized grow out strategies – either in open water or on land. 

A primary key to dulse cultivation is spore accessibility, which traditionally relies on collection from wild beds within the natural fertility window. However, wild collection is expensive and not considered sustainable and thus, proper in-house seedstock control is essential to remove this reliance on wild harvest and at the end develop sustainable production methods. 

The bottlenecks identified to secure a reliable spore supply are: 1) reliable fertility induction and, 2) the establishment of a seed bank for all-year use. 

Additionally, innovative hatchery and seeding methods will be developed to maximise spore use and seeding quality. 

Grow out will be developed with new systems at sea and on land. 

Tasks

WP3 will bring dulse production towards a stable production of commercial quantities by the following five tasks:

  1. Out-of-season fertility induction. 
  2. Seed bank for year-round seed supply. 
  3. Innovative hatchery and seeding methods. 
  4. Cultivation systems at sea and on land. 
  5. Technology development. 

Partners

  • DTU Aqua (lead of WP3)
  • Ocean Rainforest
  • Pure Algae
  • Kerteminde Seafarm.

Learn more about the partners in LTA BOOST 

Production of dulse – from spore to harvest

Fertile tissue on the dulse plants is identified. The mature spore tissue appears as a darker, thickened pattern on the leaf.
Close-up of a fertile area of a dulse leaf. The red dots are the spores.
Spores released from the mature spore tissue at the bottom of a spore collection bucket. The filter in the bucket retains the spores.
After the release of the spores, they are blended before they can be used for seeding. This is necessary because the spores are released in clusters but must be separated for a homogeneous seeding.
Section of a line with seeded spores. Some spores have developed into small, elongated seedlings. The spores can be sown directly on lines or nets, or they can grow in cultures in land-based systems without adhering.
When the seedlings are large enough, they are deployed at sea for further growth. The deployment typically takes place in the autumn (September-October).
The dulse grows during the winter and can be harvested in spring.
Schematic production cycle of dulse
Schematic production cycle of dulse. Modified from FAO.