UW News

September 25, 2019

Fish micronutrients ‘slipping through the hands’ of malnourished people

man selling fish

A fish market.Tane Sinclair-Taylor

Millions of people are suffering from malnutrition despite some of the most nutritious fish species in the world being caught near their homes, according to new research published Sept. 25 in Nature.

Children in many tropical coastal areas are particularly vulnerable and could see significant health improvements if just a fraction of the fish caught nearby was diverted into their diets.

As well as omega-3 fatty acids, fish are also a source of important micronutrients such as iron, zinc and calcium. Yet more than 2 billion people worldwide suffer from micronutrient deficiencies, which are linked to maternal mortality and stunted growth, among other conditions.

This new research, led by an international team including the University of Washington, suggests enough nutrients are already being fished out of the oceans to substantially reduce malnutrition and, at a time when the world is being asked to think more carefully about where and how we produce our food, fishing more may not be the answer.

“Nearly half the global population lives within 100 kilometers (62 miles) of the coast. Half of those countries have moderate to severe deficiency risks; yet, our research shows that the nutrients currently fished out of their waters exceeds the dietary requirements for all under age 5 within their coastal band. If these catches were more accessible locally they could have a huge impact on global food security and combat malnutrition-related disease in millions of people,” said lead author and professor Christina Hicks of Lancaster University’s Environment Centre.

The research team collected data on the concentration of seven nutrients in more than 350 species of marine fish and developed a statistical model for predicting how much nutrition any given species of fish contains, based on their diet, sea water temperature and energy expenditure.

This modelling allowed researchers to accurately predict the likely nutrient composition of thousands of fish species that have never been nutritionally analyzed before.

fishing boat on water

A fishing vessel.Tane Sinclair-Taylor

Using current fish landings data, they quantified the global distribution of nutrients available from existing marine fisheries. This information was then compared with the prevalence of nutrient deficiencies around the world.

Their results showed important nutrients were readily available in the fish already being caught, but they were not reaching many local populations that were often most in need.

For example, the amount of fish currently caught off the West African coast — where people suffer from high levels of zinc, iron and vitamin A deficiencies — was sufficient to meet the nutritional needs of the people living within 100 kilometers (62 miles) of the sea.

Parts of Asia, the Pacific and the Caribbean were some of the other coastal regions showing a similar pattern of high malnutrition, despite sufficient fish nutrients in the local catch.

Researchers say that a complex picture of fisheries policies, global-local market interactions and international and illegal fishing — along with varied cultural preferences or aversions to seafood — are standing between malnourished people and the more-than-adequate fish nutrients caught on their doorstep.

“Our food systems are a mosaic of local and global products, and fish are among the most internationally traded foods,” said co-author Eddie Allison, professor in the UW School of Marine and Environmental Affairs. “There are two ways in which seafood slips out of the hands of the poor. One is that lower-cost, often highly nutritious small, oily fish are the basis for the world’s aquaculture, animal feeds and pet food trades. These markets can pay as much or more than low-income consumers for their fish. The second is that the demand for high-quality imported seafood in wealthy countries means that our fishery management systems and markets tend to funnel fish toward those who can pay the most for it. Fisheries management has to be orientated more toward contributing to human nutrition if we want to close this nutrition gap.”

Other co-authors are Philippa Cohen, Coralie D’Lima, David Mills, Matthew Roscher and Shakuntala Thilsted of WorldFish; Nicholas Graham of Lancaster University; Kirsty Nash of the Institute for Marine and Antarctic Studies at the University of Tasmania; Andrew Thorne-Lyman of Johns Hopkins Bloomberg School of Public Health; and Aaron MacNeil of Dalhousie University.

The research was funded by the European Research Council, Lancaster University, the ARC Centre of Excellence for Coral Reef Studies, the Royal Society University Research Fellowship, the Canada Research Chairs program, the Australian Centre for International Agricultural Research and the U.S. Agency for International Development.

For more information, contact Allison at eha1@uw.edu or Hicks at christina.hicks@lancaster.ac.uk.

This was adapted from a Lancaster University news release.