In 2003, the Irish seaweed industry employed nearly 500 people (full-time and part-time), exported 85-90% of its produce, and had a turnover of over €12 million. This somewhat unusual industry had a very high employment: export ratio, activity was mostly concentrated on the western seaboard, and most collection took place in areas that are - by European Union standards at least - severely disadvantaged.

The size of the Irish industry should be considered in relation to the international seaweed industry. About 7 million t of seaweeds (wet weight) were produced world-wide in 1993 of which some 65% was food-grade (Anon. 1997). Brown algae accounted for 4.9 million t, of which Chinese production alone of the food kelp Saccharina japonica was 4 million t alone. Japan produced an additional 300,000 t of this kelp making a total in 1995 of about 4.3 million t, which probably makes Saccharina japonica the largest single-species crop produced by aquaculture in the world. Some 250-300,000 t of this material is used in China to make about 7,000 t of alginates, viscous polysaccharides used in a wide variety of industrial applications, particularly in the food industry. In addition, Japan and Korea in 1993-4 produced about 21,000 million sheets of nori (about 550,000 wet t). Nori is a red alga (mainly Porphyra yezoensis), and this crop is worth about US$1.5 billion, the most valuable single-species crop produced by aquaculture in the world. The third most valuable food species is wakame (Undaria pinnatifida) of which 750,000 t were produced in Japan, Korea and China in 1995. In 1995, by contrast, the only European production of seaweed by aquaculture was 8 wet t of wakame in Brittany, and even this small amount was more than adequate to satisfy demand.

Most of the remaining seaweed harvesting and aquaculture goes to fuel the production of the three families of seaweed polysaccharides known as seaweed gums: alginates from brown algae, and carrageenans and agars from red algae. The wholesale value of these gums is about US$950 million. The total worth of the international seaweed business exceeds US$6 billion, of which Ireland had only a very small percentage.