Using the sea for food production

A recent study from the Friedman School of Nutrition Science and Policy at Tufts University has suggested that farmers could shift from land to sea to help solve hunger and malnutrition. The study was published in Global Food Security.

According to Patrick Webb, the Alexander McFarlane Professor of Nutrition at the Friedman School and senior author of the study, farmers in low- and middle-income countries (LMICs) could have their incomes boosted by producing and selling seaweed, particularly in coastal regions of Africa and South-East Asia. Other authors include Natalie Somers and Shakuntala Thilsted, who works for the Consultative Group on International Agriculture Research and won a 2021 World Food Prize for research and innovation in aquaculture and food systems. The team reviewed research papers, existing databases, United Nations and World Bank Group reports and more.

Seaweed cultivation can provide a more sustainable alternative to raising livestock as it requires no land, fresh water or chemical fertilisers. The study found that it could also become particularly profitable as demand for nutrient-rich seaweed products grows around the world.

According to Webb, the unaffordability of healthy diets is one of the biggest problems of food insecurity in the LMICs. He said there are about 3.5 billion people who can’t afford a healthy diet, something which cultivating and selling seaweed may help to resolve.

According to the study, seaweed has been grown in parts of Asia for centuries using fairly simple techniques and is a friendly crop for both farmers and the environment.

To start, farmers attach long lines of rope to the roots of the algae, which nourish the plant by absorbing nutrients from the water. Six to eight weeks later, they gather the seaweed by hand and dry it in the sun.

Seaweed also has a small carbon footprint and may even help lower the ocean’s carbon levels. Little is known about how much CO₂ seaweed releases during harvest, but research has found that perennial brown algae farms absorb up to ten tonnes of CO₂ per hectare of sea surface per year. When added to livestock feed, seaweed could also help reduce methane gas emissions.

“Unless we get significant warming of the oceans, cultivating seaweed offers a way that is not just climate friendly, but climate-proof,” Webb said. “We don’t know how soon the industry will start to experience the negative effects of climate change, but the potential looks good. By farming seaweed, it’s not going to accelerate those negative effects. Whereas cutting down trees and adding more livestock certainly would.”

While seaweed farming helps the environment, climate change may present barriers to growing more of it. According to the authors, ocean water is becoming increasingly acidic, which is not ideal for growing healthy, edible seaweed.

The study also found that seaweed’s primary value as an export would be for its extracts as ingredients, rather than as a sea vegetable to be eaten whole. Additionally, most LMICs do not already have the infrastructure needed to process, test and regulate seaweed.

According to Webb, there is limited research and little data on bottlenecks and the patterns of end users, so governments and entrepreneurs in many LMICs have had few resources or incentives to invest in aquatic plant farming.

Webb said there needs to be a focus on the steps taken between the farm and the fork, by working with governments and the private sector to figure out where the bottlenecks are and how to overcome them.

The authors believe that the opportunities of seaweed aquaculture are boundless if these obstacles can be addressed. In Indonesia, this industry has flourished due to steadily available seasonal labour. The country is now a key exporter of two seaweed species from which carrageenan, a thickener found in nut milks and meats, is extracted.

“There are many different types of seaweed, and they all require somewhat of a different environment in which to grow. The vast coasts of Africa and Asia; not all of it will be prime real estate,” Webb said. "But much of it will be.”

To expand seaweed farming in these places, governments must take it seriously and create food safety regulations and an overall environment where it can happen. Local and international investment interest will also be key, according to Webb.

Image credit: iStock.com/Wiyada Arunwaikit