The expansion and impact of world fishing fleets in a) 1950 and b) 2006. The maps show the geographical expansion of world fishing fleets from 1950 to 2006 (the latest available data). Since 1950, the area fished by global fishing fleets has increased ten-fold. By 2006 100 million km2, around 1/3 of the ocean surface, was already heavily impacted by fishing. worldwildlife.org

The expansion and impact of world fishing fleets in a) 1950 and b) 2006. The maps show the geographical expansion of world fishing fleets from 1950 to 2006 (the latest available data). Since 1950, the area fished by global fishing fleets has increased ten-fold. By 2006 100 million km2, around 1/3 of the ocean surface, was already heavily impacted by fishing.

Primary production rate (PPR) is a value that describes the total amount of food a fish needs to grow within a certain region. Blue: At least 10% PPR extraction; orange: At least 30% PPR extraction; red: At least 20% PPR extraction.  worldwildlife.org

The consequences of increased fishing intensity have been dramatic for the marine environment. Between 1950 and 2005, “industrial” fisheries expanded from the coastal waters of the North Atlantic and Northwest Pacific southward into the high seas and the Southern Hemisphere.

Improved fishing technology allowed deep-sea trawling, purse seining and long-lining in waters several kilometres deep, reaching populations that are long lived, late maturing and very sensitive to overfishing. One-third of the world’s oceans and two thirds of continental shelves are now exploited by fisheries, with only inaccessible waters in the Arctic and Antarctic remaining
relatively unexploited.

A nearly five-fold increase in global catch, from 19 million tonnes in 1950 to 87 million tonnes in 2005 (Swartz et al., 2010), has left many fisheries overexploited (FAO, 2010b). In some areas fish stocks have collapsed, such as the cod fisheries of the Grand Banks of Newfoundland (FAO, 2010b). Catch rates of some species of large predatory fishes – such as marlin, tuna and billfish – have dramatically declined over the last 50 years, particularly in coastal areas of the North Atlantic and the North Pacific (Tremblay-Boyer et al., 2011). This continuing trend also applies to sharks and other marine species.

Targeted fishing of top predators has changed whole ecological communities, with increasing abundance of smaller marine animals at lower trophic levels as a consequence of the larger species being removed. This in turn has an impact on the growth of algae and coral health.

2012 Living Planet Report [pdf]

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