Aquaculture for all
The Fish Site presents: The Vienna Sessions - Conversations about aquaculture. 9 video interviews with aquaculture thought leaders. Watch here.

Restoring Oysters Could Restore a Health Threat

US - Asian oysters may be able to repopulate and help clean up the Chesapeake Bay, but many peopl are worried about the health dangers that come with this proposal.

According to the Baltimore Sun, there are questions about whether the fast-growing imports would be more likely than the now-depleted native oysters to pick up and pass along along human disease pathogens or viruses.

Researchers at Johns Hopkins' Bloomberg School of Public Health have found that Crassostrea ariakensis, aka the Asian or Suminoe oyster, collected and retained viruses that cause gastro-intestinal illness in humans, such as norovirus and hepatitis A. Their findings were published in last month's Applied and Environmental Microbiology, reports the Baltimore Sun. The Johns Hopkins student newspaper, the News-Letter, featured the study last week, after I reported on the findings of a draft Environmental Impact Statement studying Asian oysters as a possible remedy to the decimation of the bay's native oysters.

A couple years ago, the same researchers found that Asian oysters were more likely to pick up and accumulate spores of Cryptosporidium, a water-borne microorganism that also can cause gastro-intestinal illness in humans. That study was published in 2006 in Applied and Environmental Microbiology.

The Baltimore Sun reports that, the oysters tested by researchers had been chemically sterilized, so they grew faster than reproducing oysters. Such sterile, or triploid, oysters are being considered for use by private aquaculture operations in Virginia and Maryland because they can reach market size in a year or less, compared with three years for wild-growing native oysters.

Oysters of all types have long been recognized as a health threat when eaten raw because of their tendency to collect pathogens from contaminated water. It's believed that the Asian oyster may pick up more pathogens than the bay's native Eastern oyster, Crassostrea virginica, perhaps because it filters more water to feed its faster growth.

Further Reading

- You can view the full report by clicking here.