In its most general form, overfishing means that humans take out more fish and other organisms from the oceans (and freshwaters) than the affected ecosystems can regenerate. As a result, the more one fishes, the less can be harvested. Persistent overfishing may lead to the disappearance (entirely or at least commercially) of a formerly abundant resource.

  • When we catch lots of baby fish and don't let them grow to the size, where they would normally reproduce and sustain a fishery, we call that recruitment overfishing. We then not only catch much less than would otherwise be possible on a sustainable basis, but jeopardise the existence of this productive resource. When poor people catch whatever they can for lack of alternatives and ruin their own livelihoods in the process, we call that Malthusian overfishing.

  • We also distinguish an economic form of overfishing, when we the fisheries uses more production means than makes economic sense and does not generate a net benefit to society (e.g. when governments pay bad subsidies to the fishing fleet, which has already over-harvested a resource). You then have the many paying for unsustainable practices of the few.

Some facts

  • Several major fisheries have already spectacularly collapsed as a result of overfishing: among them the once-famously rich cod fisheries off Newfoundland in Canada, which collapsed in 1993 and have not bounced back. The misery brought about by the collapse of sardine fishery off Monterrey, California, came to sad notoriety thanks to the novel 'Cannery Row' by John Steinbeck, published in 1945.

  • 80% of global fisheries are fully exploited or overfished. FAO states that only 20% are not yet fully exploited and no big new fisheries are opened up. 90% of the biomass of big fishes (e.g. tuna, marlins, sharks, cod and halibut) have already disappeared.

  • In the North Atlantic (between Europe and North America) the abundance of such big fish has shrunk by 2/3 between 1950 and 2000 and by a factor of nine over the last century 1).
  • If current exploitation trends continue, the fisheries we know today and the species they rely on for today's catch will be gone by around 2050 2). See this video about overfishing on YouTube.
  • Industrialised countries which have greatly reduced the productivity of the marine ecosystems at home through overfishing 'export' the overcapacity of their fleets and now fish further south and further down in the oceans.

  • The weaker government capabilities to legislate and police their waters are, the more unwise and even illegal fishing is attracted. West Africa is one of the regions where overfishing has been aggravated according to the FAO.

  • Overfishing leads to the reduction of the productive base of marine ecosystems. It's been a process that has gone on for a long time, but has accelerate with the growth of human populations, motorisation of fleets and massive deployment of other technologies. This is why global catches from wild stocks are declining since the late 1980s. Marine ecologists think that overfishing is the single most important disaster for marine ecosystems around the globe, even though recent management measures have attenuated the situation in some areas.

  • In 1970, some 600,000 decked fishing vessels (mostly with an inboard engine) were registered. In 1980, their number had grown to 800,000 and in 1990 to 1.2 million. The total number of fishing vessels in the world in 2014 is estimated at about 4.6 million. Open fishing vessels without a deck, with or without engine followed a similar trend.

  • Between 1980 and 1995 the Chinese fleet expanded massively and now accounts for about 1/3 of global fishing capacity. FAO estimated some 3.5 million fishing vessels in 2014 in Asia, almost 75% of the global fleet.

  • Globally, 64 percent of reported fishing vessels were engine-powered in 2014, of which 80 percent were in Asia, with all other regions under 10 percent each. 
  • In 2014, about 85 percent of the world’s motorized fishing vessels were less than 12 m in length overall (LOA), and these small vessels dominated in all regions.

  • The estimated number of fishing vessels of 24 m and longer operating in marine waters in 2014 was about 64 000, the same as in 2012.

  • Already in 1990 FAO demanded that the fishing fleets of the world should shed 1/3 of their capacity to avoid further overfishing of resources and uneconomical investment.

  • In reality, not only has the tonnage of the global fleet expanded massively in the last decades, but technological innovation such as echo sounders, radar, satellite navigation, high performance gear, particularly trawling, are enabling fishing in areas, which used to be inaccessible and natural refuges for marine life.

  • Destructive and wasteful trawling and other high impact gears have no future. Rather we should set ourselves the objective of re-developing well-managed small-scale coastal fisheries, which are selective and in tune with nature and society.

  • Hear the interview with Rainer Froese on Deutsche Welle (in English) about how to get out of overfishing, restore the oceans natural wealth and produce more fish sustainably as well.

1) Christensen, V. et al., 2003. Hundred-year decline of North Atlantic predatory fish. Fish and Fisheries, 4:1-24.

2) Worm, B. et al., 2006. Impact of biodiversity loss on ocean ecosystem services. Science, 314(5800):787-790.

For a more extensive definition of biological overfishing, see Pauly, D. 1979. Biological overfishing of tropical stocks. ICLARM Newsletter 2(3): 3-4.

The Sea Around Us Project makes the most up-to-date reconstruction of extractions of marine fisheries in each country and major territory or island publicly available compared to the to official records.