Seaweed harvesting

The two main types of seaweed that are harvested in Scotland are the egg wrack Ascophyllum nodosum and kelp, usually Laminaria hyperborea.

Calming the storms

Both types of seaweed play important roles in supporting biodiversity and wider marine ecosystems. Seaweeds are a valuable source of food for all sorts of animals, both directly for those that graze on the seaweeds themselves, and indirectly for those that feed on the large amounts of organic matter released by seaweeds into coastal waters. Seaweeds also provide different habitats for other marine plants and animals. There is some evidence to show that kelp forests provide nursery grounds for fisheries (both finfish and shellfish) as well as providing food resources for seabirds. In addition, large Laminaria hyperborea forests, for example to the west of the Western Isles, play an important role in storm protection by reducing wave energy reaching the coast. The importance of seaweed is also recognised through its inclusion within a number of designated sites.

A tangled story

Seaweed is an important resource which may be harvested sustainably, however sustainable management is not straightforward. Seaweeds have complicated life histories. Failure to take account of this in the management of harvesting operations can have knock-on effects. Damage to growing areas of individual plants can affect regeneration. Sea urchins may also choose to feed on young plants and opportunistic seaweeds may outcompete those which are the subject of harvesting. .

Bringing the harvest in

Commercial operations are currently undertaken in the Northern and Western Isles. The main interest is in alginates which are used in foods, textiles and pharmaceuticals. There is also some commercial use of seaweeds as organic fertilisers. More recently there has been interest in evaluating large-scale harvesting of seaweeds in Scotland for use as biofuels. The most common method of harvesting is by hand cutters.