US – Researchers in the US have, for the first time, quantified the amount of freshwater that would be needed to replace marine protein in our diets with protein produced on land. Jessica Gephart and her colleagues from the University of Virginia, US, believe that quantifying water footprints in this way is an important tool for evaluating food and water security.
“Marine fish production requires little or no freshwater, whereas generating terrestrial protein such as meat, eggs or crops requires large amounts of water,” Ms Gephart told environmentalresearchweb. “So consuming marine protein instead of terrestrial protein represents a freshwater saving and contributes to a low water footprint diet.”
Calculating the water footprints of different food groups also helps to identify countries that may struggle to produce adequate supplies of protein should populations of marine fish decline.
Gephart and her colleagues found that, globally, replacing marine protein with terrestrial protein would require an additional 350 cubic km of water per year. As an estimated 7600 cubic km of water per year is used for human food production, marine protein currently provides water savings of 4.6 per cent.
While this global figure is relatively small, the researchers found that in some countries the saving can be as high as 50 per cent.
“We found the highest water saving from marine protein in the Maldives,” said Ms Gephart. “This figure shows that the Maldives are very dependent on marine protein and as the amount of land available for capturing freshwater and producing terrestrial protein is small, the Maldives may struggle to generate enough terrestrial protein domestically should fish stocks decline.”
As well as the Maldives, the team rated the Republic of Korea and Barbados as receiving the greatest water benefit from marine protein, and consequently as most vulnerable to the loss of this protein. Only four countries have sufficient renewable water resources but insufficient land: Japan, Brunei Darussalam, Trinidad and Tobago, and Bangladesh.
“These countries may be able to increase terrestrial food production if yield can be increased on available agricultural land,” said Ms Gephart. “But they may be more likely to import terrestrial protein.”
The researchers also identified countries that have sufficient land, but insufficient water. These include much of the Middle East and North Africa, and parts of Sub-Saharan Africa.
Ms Gephart hopes the study, which has been published in Environmental Research Letters (ERL), will highlight the fact that water resources and food security are often linked, directly or indirectly.