Mariculture: Farming Seaweed for Carrageenan

Erick Ask, FMC Biopolymers, USA

FMC’s biopolymers division produces carrageenan from seaweed the company purchases in Norway, Estonia, Canada, the U .S ., Chile, Peru, the Philippines, Indonesia, Fiji, Vietnam, Tanzania, Madagascar, Morocco and Mozambique . Used as a thickener in food and other products like toothpaste, carrageenan demand has pushed the worldwide commerce in seaweed to $2 .9 billion annually . Once harvested from wild populations, seaweed used commercially is now primarily produced by families who farm the shallow sea according to practices developed by FMC in the 1960’s .

The species Cottoni spinosum is most commonly cultivated by seaweed farmers whose underwater fields resemble rice paddies when viewed from an airplane . About 70,000 families around the world farm seaweed . In 2003, 150,000 tons of seaweed were grown . Three systems are used to grow seaweed – suspending it from a system of rafts, using stakes in the sea bottom for structure and extending long nylon lines that are kept submerged . Recently, Philippine farmers have developed a low-labor system where seaweed rests inside pens on the sea bottom .

In prime conditions, the biomass of Cottoni spinosum increases ten-fold in 6 weeks . As with farming on land, management is critical to high yields . Pests include rabbit fish, which eat seaweed and red algae which infect it when salinity drops too low . When seawater is too warm, seaweed suffers from warm water die-off . Heavy wave action from storms raises havoc by tearing seaweed from its moorings and tangling rope lines from which it grows .

Once harvested, seaweed is placed on drying tables in shady locations where it takes about 3 days to it reach 30 percent moisture, the point at which it is a stable, marketable product . When seaweed is brought to drying tables, healthy sections – or propagules – are collected and returned to the water for reseeding .

Seaweed farming generates direct environmental benefits by creating habitat that supports fish where previously only sandy bottoms existed . By offering communities a sustainable way to make a living, it reduces environmentally harmful activities such as harvesting coral and killing endangered sea turtles . Most seaweed operations are small businesses, many of which are owned by women, since tending the plots can be organized around child care and other household duties . In Tanzania, 85 percent of seaweed farms are owned by women . The best way to support this sustainable way of life for thousands of families is to buy products with carrageenan in them .

Biographical Sketch

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