Foreign fishing fleets are worsening food and nutrition insecurity in some of the world’s most vulnerable coastal countries, according to a new study which found that keeping locally-caught fish in local markets could improve nutrition for up to 10.6 million people across 35 countries.

The research, led by scientists at the ocean conservation group Oceana and published in the journal npj Ocean Sustainability, found that foreign trawlers catch more than six million metric tonnes of fish a year in the waters of countries that rely most heavily on the ocean for food – many of them in West Africa. Much of this catch is then shipped abroad rather than sold domestically.

Many of the foreign vessels use bottom trawling, a fishing method that drags heavy nets across the seafloor and is widely regarded as one of the most destructive forms of commercial fishing.

The study found that this pattern is creating a global nutrient imbalance, moving nutrient-rich wild fish out of countries with high levels of malnutrition and into wealthier, more nutritionally secure markets.

“Behind these numbers are real communities. In many coastal countries, especially in West Africa, fish is one of the most accessible sources of essential nutrients for people’s health and well-being,” said Dr David Costalago, the study’s lead author and a senior marine scientist at Oceana.

Researchers found that Guinea-Bissau, Guinea, The Gambia, Sierra Leone and Côte d’Ivoire stood to see some of the largest nutritional gains if more of the catch were retained locally. In Guinea-Bissau, where 99.9% of the population is deficient in calcium, researchers found that eating the retained catch could bring most people up to an adequate intake of the nutrient.

“Aquatic foods are among the richest natural sources of nutrients that many people around the world lack, including vitamin B12, iron, zinc, calcium, and omega-3 fatty acids,” said Dr Chris Golden, a co-author of the study, Oceana science advisor and associate professor at Harvard T.H. Chan School of Public Health. 

He said the findings showed that how fisheries are managed and how seafood moves through global markets can have significant consequences for human nutrition, particularly where deficiencies are already widespread.

The researchers said governments could address the imbalance by building food and nutrition security into fisheries management and foreign access agreements, improving transparency around foreign fishing activity, and prioritising policies that ensure coastal communities benefit from fish caught in their own waters.

“Policymakers should ensure that fisheries access agreements and management decisions explicitly consider food and nutrition security alongside economic and environmental objectives,” said Costalago. “Doing so could help make ocean resources work better for the people who need them most.”

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