An incredibly big and serious decline of 49% has taken place in the numbers of marine animals between 1970 and 2012. This is one of the main results of an updated study of marine mammals, birds, reptiles and fish published in September 2015. WWF Living Blue Planet report is based on research results summarised by the Zoological Society of London. Overall, 5,829 populations of 1,234 species were studied.
Not only numbers of marine vertebrate species have plummeted, also the increasing decline of marine habitats is alarming. The deforestation rate of mangroves, which offer many on-site and off-site ecological and economic benefits, has been 70% between 1970 and 2010. Equally important wetland areas, the world’s seagrass habitats have lost about 30% of their total area the since 1879. Seagrasses store double the amount of carbon stored by on-land forests.
As regards coral reefs, where 25% of all marine species can be encountered, their live coral cover has decreased by more than 50% during the past 30 years. In addition, there has been a 34% decline in reef fish populations between 1979 and 2010. The report says that due to climate change (ocean warming and acidification), the live cover of coral reefs could practically be lost across the globe by 2050 – at least as regards the main reef component the stony corals, which are the main reef builders.
Regarding fish stocks (930 species and 1463 populations studied) there has been a 50% reduction in population numbers around the globe between 1970 and 2010. 29% of commercial fish stock are considered as overexploited. 61% of the stocks are classed as fully exploited.
As to such important food fish as mackerels, tuna, bonitos and their Scombridae relatives, there has been a 74% decline between 1970 and 2010. Also sharks, rays and skates are facing survival threats: global catches have increased dramatically and 25% of the populations are threatened by local extinction.
Bottom trawling is in difficulties as well: There has been a 72% decrease in catches during the last 40 years. As to deep sea trawling specifically, this practice can be considered mostly unsustainable.
Of the four marine turtle species facing survival threats, the leatherback is having the biggest problems with 4 of the 7 sub-populations critically endangered.
Living Blue Planet Report indicates that also seabird and shorebird populations commonly face threats. The same is true for pinnipeds (seals, sea lions, sea elephants and walruses). Other marine mammal populations (whales & dolphins) and sirenians (manatees & dugongs) were not assessed in detail in this study – the information of their population development is considered data deficient. Also most marine invertebrates belong to the same “data deficient” category and detailed information regarding their conservation status is not available.
One of the press releases presenting the report summarises the findings of Living Blue Planet in the following words:
“As well as being disastrous for ecosystems, these findings spell trouble for all nations, especially people in the developing world who depend heavily on the ocean resources.”
“While over-exploitation is identified as the major threat to ocean biodiversity, the study finds that climate change is causing the ocean to change more rapidly than at any other point in millions of years. Rising temperatures and increasing acidity levels caused by carbon dioxide are further weakening a system that is already severely degraded through overfishing, habitat degradation and pollution.”
“By over-exploiting fisheries, degrading coastal habitats and not addressing global warming, we are sowing the seeds of ecological and economic catastrophe.”
“But there are clear steps that all governments can take to restore our oceans. Creating networks of well-managed marine protected areas is a proven way to enable wildlife and habitats to recover. Pushing for a strong global deal on climate change would help the seas sustain life far into the future.”
Living Blue Planet Report 2015 can be downloaded from these two web sites: