In a study released on Tuesday, the Swiss-based World Wildlife Fund blamed human threats to nature for the decline particularly in tropical regions like Latin America.
The group described the study it has carried out every two years since 1998 as a barometer of the state of the planet.
“There is no room for complacency,” said WWF International Director General Marco Lambertini, calling for a greater focus on sustainable solutions to the impacts that people are inflicting on nature, particularly through the release of greenhouse gases.
The latest “Living Planet” study analyzed data from about 10,000 populations of 3,038 vertebrate species from a database maintained by the Zoological Society of London.
It is meant to provide a representative sampling of the overall wildlife population in the world, said WWF’s Richard McLellan, editor-in-chief of the study.
It reflects populations since 1970, the first year the London-based society had comprehensive data. Each study is based on data from at least four years earlier.
In the new WWF study, hunting and fishing along with continued losses and deterioration of natural habitats are identified as the chief threats to wildlife populations around the world.
The same report two years ago put the decline at 28 percent between 1970 and 2008.
The worst decline was among populations of freshwater species, which fell by 76 percent over the four decades to 2010, while marine and terrestrial numbers both fell by 39 percent.