The killing seas
Autor: Fermin Koop
|Half of the world’s marine population has been killed off over the last four decades due to pollution, industrial fishing and climate change, according to a report by the World Wildlife Fund (WWF) released this week.
The Living Blue Planet Report indicates that marine species critical to human food security may be suffering the greatest declines. Underscoring the severe drop in commercial fish stocks, the report details the loss of 74 percent of the family of popular food fish that includes tunas, mackerels and bonitos.
The findings are based on the Living Planet Index, a database maintained and analyzed by researchers at the Zoological Society of London. The analysis tracked 5,829 populations of 1,234 marine species, making the data sets almost twice as large as past studies.
"The sea offers many more environmental services than we actually know. It’s not valuable just for the fish, it helps to control the weather and reduce carbon emissions," Guillermo Cañete, biologist and head of the Marine Programme of the Vida Silvestre Foundation, told the Herald. "But pressure on the sea is growing as there’s more people on the planet who need to be fed."
Adding to the falling fish populations crisis, the report shows steep declines in coral reefs, mangroves and seagrasses that support fish species and provide valuable services to people.
Over 30 percent of fish tracked by the report rely on coral reefs, and these species show a dangerous decline of 34 percent between 1979 and 2010.
According to the report, coral reefs could be lost across the globe by 2050 as a result of climate change. With over 25 percent of all marine species living in coral reefs and about 850 million people directly benefiting from their economic, social and cultural services, the loss of coral reefs would be a catastrophic extinction with dramatic consequences on communities.
While over-exploitation is identified as the major threat to ocean biodiversity, the report 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 aggravate the negative impact of overfishing and other major threats including habitat degradation and pollution.
Beyond the obvious harm to nature, threats to the ocean risk annual economic output of at least US$2.5 trillion and an overall asset base of at least US$24 trillion, as found by a previous study.
Cañete highlighted that Argentina has the "privilege" of having a highly-productive sea in better shape than those in the rest of the world. The country has one of the largest continental shelves in the world, with more than one million square kilometres in which a large variety of ecosystems live. More than 600 vertebrate species live in the Argentine sea, as well as thousands of invertebrates.
"We don’t have a sea as polluted and damaged as in the rest of the world. Only a few large cities in Argentina are affecting the sea. There are negative effects because of oil exploitation in the San Jorge bay, where we can find penguins covered in oil, and in Tierra del Fuego," Cañete said. "But that doesn’t mean we should keep still and do nothing."
The WWF stressed that marine life can be restored if the human population starts to live within sustainable limits. The report said the protected global ocean area — currently about 3.4 percent — should be tripled by 2020. It also called on consumers and fish retailers to seek supply from companies that follow certified "best practice" standards.