Marine foods sourced from farther as their use of global ocean primary production increases

Abstract

The growing human population must be fed, but historic land-based systems struggle to meet expanding demand. Marine production supports some of the world's poorest people but increasingly provides for the needs of the affluent, either directly by fishing or via fodder-based feeds for marine and terrestrial farming. Here we show the expanding footprint of humans to utilize global ocean productivity to feed themselves. Our results illustrate how incrementally each year, marine foods are sourced farther from where they are consumed and moreover, require an increasing proportion of the ocean's primary productivity that underpins all marine life. Though mariculture supports increased consumption of seafood, it continues to require feeds based on fully exploited wild stocks. Here we examine the ocean's ability to meet our future demands to 2100 and find that even with mariculture supplementing near-static wild catches our growing needs are unlikely to be met without significant changes.

Figure 1. Historical and projected use of global oceans.

(a) The median minimum distance 1950–2011 that seafood is sourced from where it is consumed (bootstrap methods supply 95% confidence limits indicated by blue shading) combines wild capture and mariculture using the mapped position of origin directly to the nearest port where consumed. (b) The area of ocean used to supply seafood for 1950–2011 using the % of annual primary productivity required (PPR) of the available primary productivity (PP) for three exploitation levels (>10% (green), >20% (yellow) and >30% (red)) assuming fixed trophic transfer efficiencies for the associated mapped landings. (c) Percentage of ocean PPR to PP used from currently accessible ocean areas (depth <1,000 m) assuming fixed trophic transfer efficiencies for the associated mapped landings for 1950–2011. Monte Carlo methods provided the 95% confidence shading in blue. (d) Global consumption of seafood 1950–2011 and projected to 2100 based on the UN's high, low and median levels of population estimates. Solid diamonds are FAO/UN's future consumption estimates. Horizontal lines represent the estimated limits to global seafood production (wild and farmed combined) assuming limits to the fishmeal (marine-sourced) input to mariculture feeds restricted to 10% (lowest line), 7 and 5%, respectively (highest line).

Figure 2. Where global seafood was historically produced and consumed.

(a) Production in 1950s: the % of primary productivity required (PPR) of average primary productivity (PP) available to support seafood catches within country's exclusive economic zone (EEZ). (b) National consumption estimated for circa 1961 in kg per capita. (c) Production in 2000s: the % of primary productivity required (PPR) of average primary productivity (PP) available to support seafood catches within country's EEZ claims. (d) National consumption for 2009 in kg per capita.