Vertebrate populations have declined by 69% in less than fifty years – Le Monde

A dugong feeding on sea grass, with golden trevallies, in Thornbury, Australia, in October 2013. KELVIN AITKEN-V&W /AP Every two years, the World Wide Fund for Nature (WWF) assesses the abundance of populations of wild vertebrates, through its “Living Planet Index” (LPI). And, every two years, this indicator describes a decline that increases, inexorably. According to the latest edition of the report, published Thursday, October 13, the populations of birds, fish, mammals, amphibians and reptiles have declined by an average of 69% between 1970 and 2018. In 2020, the same indicator reported from a drop of 68%. “A drop of 1% in two years is colossal, and we have lost 10 points in ten years, underlines Arnaud Gauffier, the program director of the WWF. On very low populations, this can be dramatic and lead to extinctions. The mere fact that this indicator is not improving is catastrophic. “Vertebrates represent less than 5% of known animal species, but are the most followed. Great Disparities In just fifty years, according to LPI, lowland gorilla populations have declined by 80%; those of African forest elephants, classified as critically endangered, by 86%. The populations of oceanic sharks and rays have also collapsed (–71%). Other populations – about half of those studied – are stable or increasing. Developed by the Zoological Society of London, the Living Planet Index calculates an average evolutionary trend for tens of thousands of populations of terrestrial, marine and freshwater vertebrates. This year, 31,821 populations representing 5,230 species were taken into account, representing 838 new species and 11,011 more populations compared to 2020 – a considerable increase. The number of species of fish (+29%) and birds (+95%) in particular, as well as data from previously underrepresented regions, such as Latin America and the Caribbean, have been greatly expanded. African Elephant, Masai Mara National Reserve, Kenya. ANUP SHAH/WWF Sea Eagle (Aetobatus narinari), Galapagos Islands. DANIEL VERSTEEG / WWF At the end of 2020, researchers had judged, in an article published in Science, that this indicator gave a “catastrophic” view of the erosion of biodiversity, estimating that the extreme decrease in certain populations affected “disproportionately » the overall average. For this new edition, the LPI has been recalculated by excluding certain species or populations. “This confirmed that the index was not driven by extreme declines or increases,” the report authors write. Read also Article reserved for our subscribers The delicate calculation of the decline of vertebrates The loss of biodiversity is particularly complicated to summarize in a figure or a measure that would achieve consensus, the phenomenon being multidimensional. “The LPI allows useful comparisons to be made from year to year and to give an order of magnitude of the loss of biodiversity, explains Michel Loreau, research director at the CNRS. But I prefer other more specialized and homogeneous studies on the decline of birds or insects, which are just as alarming. You have 61.64% of this article left to read. The following is for subscribers only.