From the World Wildlife Fund:
Global populations of vertebrates — mammals, birds, reptiles, amphibians, and fish — have declined by 58 percent between 1970 and 2012, states a new report from World Wildlife Fund (WWF). Animals living in the world’s lakes, rivers, and freshwater systems have experienced the most dramatic population declines, at 81 percent. Because of human activity, the report states that without immediate intervention global wildlife populations could drop two-thirds by 2020.
Living Planet Report 2016: Risk and resilience in a new era is the eleventh edition of WWF’s biennial flagship publication. The report tracks over 14,000 vertebrate populations of over 3,700 species from 1970 to 2012 and includes research from the Global Footprint Network and the Zoological Society of London.
Direct to Full Text Report (74 pages; PDF)