With the human population recently increasing beyond 7 billion many resource analysts are concerned about meeting basic human needs, including access to freshwater. Fisheries provide one of the most water-efficient ways of supporting the human diet, but may be unsustainable due to overharvesting. Although the trajectory of global fisheries remains controversial, many regional fisheries are declining and the capacity for growth of fish harvests is limited. With the sustainability of water resources and capture fisheries among the top concerns for environmentalists and managers, it is important to consider how decreasing fish protein availability would impact water resources. The water footprint of a product is the amount of water required to produce a unit of (but is not necessarily contained within) a good. Here, the water footprint concept is used quantify the potential increase in national water footprints resulting from a collapse of capture fisheries based on current consumption rates of substitute protein sources and their associated water footprints. This approach illustrates tradeoffs between losses in fisheries catches and freshwater resources.
Results/Conclusions
The impact of a loss of fisheries on water resources is unevenly distributed throughout the world ranging from increases in water footprints of as little as 0.04 to as much as 50%. The largest percent increases in water footprints occur in Asia, Oceana, Scandinavia, and several coastal African nations. The most vulnerable countries are primarily island nations, which generally obtain a large percentage of their protein from fish and are more freshwater-limited. Many European, Asian, and coastal African countries would also experience a large increase in water footprints due to their high fish protein consumption levels. Many of these countries are not currently facing water scarcity, but an increase in terrestrial food production may not be possible due to arable land constraints. Countries which are less dependent on fish protein, but already experience water scarcity, such as Northern Africa and the Middle East, are also particularly vulnerable to fisheries declines because even small increases in freshwater demands cannot be met domestically. This unequal distribution of stress on water resources resulting from fisheries declines and the relative abilities of nations to replace lost fish protein should be integrated into future international fishing agreements to protect global food and water security.