Diminishing returns on labour in the global marine food system

Abstract

Technological advances over the past century have greatly reduced the proportion of human labour required to produce the world’s food. On land, these advances have continually increased yields, feeding a growing human population even as the number of farmers has fallen. It has long been recognized that technological advances do not necessarily increase fishery yields in the same way; since the natural productivity of wild fish stocks puts a strong limit on capture fisheries, high labour inputs can lead to overfishing. However, the global evolution of labour in marine fisheries has not been assessed, leaving the overall interactions among technology, fishers and catches unknown. Here we reconstruct the global number of marine fishers from 1950 to 2015 and show that the total number of fishers grew with no sign of reversal despite mechanization, as large increases in lower- and middle-income countries overwhelmed an ~60% decrease in higher-income countries. As a result, the wild fish catch per fisher has declined since the 1990s despite major technological advances—a stark contrast to the 70% increase of the production per farmer over the same period. Our results show that, globally averaged, fisheries displayed diminishing—or even negative—returns on labour over 1950–2015, which has been detrimental for food production efficiency, marine ecosystems and fishing communities.