Get more Mail & Guardian
Subscribe or Login

Oysters disappearing worldwide

A survey of oyster habitats around the world released on Thursday found that the succulent mollusks are disappearing fast and 85% of their reefs have been lost due to disease and over-harvesting.

Most of the remaining wild oysters in the world, or about 75%, can be found in five locations in North America, said the study published in BioScience, the journal of the American Institute of Biological Sciences.

An international team of researchers led by Michael Beck of the Nature Conservancy and the University of California, Santa Cruz, examined the condition of native oyster reefs in 40 ecoregions, including 144 bays.

“Oyster reefs are at less than 10% of their prior abundance in most bays [70%] and ecoregions [63%],” said the study.

“They are functionally extinct — in that they lack any significant ecosystem role and remain at less than 1% of prior abundances in many bays [37%] and ecoregions [28%] — particularly in North America, Australia and Europe.”

By averaging the loss among all regions, the researchers came up with an estimate that 85% of oyster reef ecosystems have been lost, but said that figure was likely low because some areas lacked historical records for comparison.

The study also did not include oyster reefs in parts of South Africa, China, Japan, and North and South Korea.

Reefs have declined in abundance
Other studies and observations in those areas “suggest that wild oyster abundance was much higher in the past and that reefs have declined greatly in abundance or have disappeared altogether”, the authors said.

The one bright spot in the oyster world was in the Gulf of Mexico, where native oyster catches are “the highest in the world despite significant declines in abundance and reefs,” according to the study.

Five regions where oyster catches were globally the highest were located in eastern North America, from the Virginia coast southward and also in the Gulf of Mexico.

Oysters are important to ecosystems because they filter impurities from water and provide food and employment for people living in coastal communities.

The decline in oyster population often begins when trawling or dredging destroys the structure of parts of the reef, leaving surviving oysters vulnerable to stresses in the environment.

In some cases, non-native species of oysters are introduced after a population decline, and they bring with them diseases that further kill off the native oysters.

The authors recommended that any reefs with less than 10% of their former abundance be closed to further harvesting until the oysters can build up their numbers again. — Sapa-AFP

Subscribe for R500/year

Thanks for enjoying the Mail & Guardian, we’re proud of our 36 year history, throughout which we have delivered to readers the most important, unbiased stories in South Africa. Good journalism costs, though, and right from our very first edition we’ve relied on reader subscriptions to protect our independence.

Digital subscribers get access to all of our award-winning journalism, including premium features, as well as exclusive events, newsletters, webinars and the cryptic crossword. Click here to find out how to join them and get a 57% discount in your first year.

Related stories

WELCOME TO YOUR M&G

If you’re reading this, you clearly have great taste

If you haven’t already, you can subscribe to the Mail & Guardian for less than the cost of a cup of coffee a week, and get more great reads.

Already a subscriber? Sign in here

Advertising

Subscribers only

Careers the Zondo state capture inquiry has ended (or not)

From Vincent Smith to Gwede Mantashe, those named and shamed have met with differing fates

The Democratic Alliance and illiberal liberalism’s glass ceiling

The DA appears to have abandoned its ambitions of 2016 and is set to lose further ground in the upcoming elections

More top stories

Careers the Zondo state capture inquiry has ended (or not)

From Vincent Smith to Gwede Mantashe, those named and shamed have met with differing fates

The Democratic Alliance and illiberal liberalism’s glass ceiling

The DA appears to have abandoned its ambitions of 2016 and is set to lose further ground in the upcoming elections

ANC Durban election candidate shot dead while on door-to-door campaign

One other man was shot dead and two others were rushed to hospital with gunshot wounds

Rule of law drops globally, including in South Africa

Security and corruption prevents the country from ranking higher on the World Justice Project Rule of Law Index for 2021
Advertising

press releases

Loading latest Press Releases…
×