Global Marine Populations Have Halved Since 1970

2422 Global Marine Populations Have Halved Since 1970
Blue fin tuna have been especially hard hit, declining by 74%. Brian Skerry/WWF

The oceans are in a dire state. A new report released today by the WWF and the Zoological Society of London (ZSL) has concluded that many marine species, including those critical to human food security, are in “potentially catastrophic decline” unless dramatic action is taken to stop overfishing and other major threats.   

“In the space of a single generation, human activity has severely damaged the ocean by catching fish faster than they can reproduce while also destroying their nurseries. Profound changes are needed to ensure abundant ocean life for future generations," said Marco Lambertini, director general of WWF International. "Overfishing, destruction of marine habitats and climate change have dire consequences for the entire human population, with the poorest communities that rely on the sea getting hit fastest and hardest.”


Global catches of sharks, such as this porbeagle shark, have increased by 300%. Perrine/WWF

The report tracked over 1,200 species of marine mammals, birds, reptiles and fish, and calculated their population trends over the last 45 years. The results are not good. The general trend is an overall decline in marine populations by 49%, but some species relied upon for food are faring even worse than that. Tuna and mackerel populations, for example, have dropped by a staggering 74%, while sea cucumber numbers have crashed by 98% around the Galapagos Islands and 94% in the Red Sea.

The reasons are numerous and varied. Overfishing takes a major portion of the blame, with an estimated 61% of global fish stocks being fully exploited and 29% overexploited, driven by a doubling in global fish consumption per capita since the 1960s. Pollution and habitat degradation in the form of the destruction of mangroves, seagrass meadows and coral reefs are further causes for concern. If all that wasn’t enough, the oceans are also being hammered by global warming, driving change more rapidly than at any other point in millions of years.

If things carry on as usual, half of all coral reefs will be bleached by 2050. Juergen Freund/WWF


“The ocean works hard in the background to keep us alive, generating half of the world’s oxygen and absorbing almost a third of the carbon dioxide produced from burning fossil fuels,” says Professor Ken Norris, director of science at ZSL. “It also feeds billions of people around the globe, some of whom rely solely on the oceans to survive. These devastating figures reveal how quickly human beings are changing the wildlife in our oceans and are a stark warning of the problems we might face as a result.”

There are actions that can be taken, but the decisions have to be made quickly. Governments need to bring overfishing under control and curb its unsustainability. Networks of well-managed marine parks, a proven way of allowing wildlife and habitats to recover, can also be created and protected. Finally, and probably most importantly, countries need to take strong concerted action on climate change.


  • tag
  • climate change,

  • coral reef,

  • oceans,

  • overfishing,

  • fish stocks