Startling numbers from a new study reveal there are half as many fish in the oceans as there were in 1970. Citing overfishing as the main cause, the report shows the Scombridae family of fish, which includes tunas and mackerels, has lost up to 75 percent of its population in that time frame. Other sharp declines include leatherback turtles and porbeagle sharks, indicating other factors have also contributed to this devastating decline in marine biodiversity.

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The World Wildlife Fund and The Zoological Society of London commissioned the study, which has yet to be peer reviewed, highlighting significant changes in the oceans’ biodiversity. Overfishing is considered a primary source of this depletion, which not only affects the specific population of fish being caught but countless other species of aquatic wildlife and their habitats. Fishing practices were once thought to be relatively harmless in the early 1900s, as it was believed that populations could compensate for the losses, yet the high demand and innovative technology advances in fishing equipment has made a far greater impact than expected.

Related: Interactive global fishing watch map to monitor activity on the open seas

Climate change is also suspected to play a starring role in this drastic shift, according to Mashable. Ocean environments are changing too quickly for life to adapt, and waters are becoming warmer and more acidic due to carbon dioxide effects. “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,” Ken Norris, the Director of Science at ZSL reported.

The WWF recommends several, simultaneous actions to combat this rising problem, including creating Marine Protected Areas (which the U.S. and U.K. have established in the last year), international governmental agencies becoming more serious and action-oriented about climate change, and finding sustainable food alternatives for human populations whom rely on the sea for sustenance.

Via Jstor Daily, Mashable

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