There were so many booths at the Merrie Monarch Festival Craft Fairs selling pearls of various colors: pink, green, white and black. It made me think of eating oysters.
These filter feeding bi-valve shellfish are one of the most environmentally friendly by filtering 50 gallons of water a day. They keep the water quality in check and keep it clean. In addition, oysters are able to sort out what they choose to consume, while mussels do not have that ability.
The gills pump sea water all day long and filter out the algae so this affects the taste as well as the salinity of the water. They not only improve the quality of the ocean water but also help their organisms in the ecosystem survive and thrive.
However, with global warming and the warming of the oceans, there are several things that affect the production of oysters. According to Sanctuary Oysters, “The water in the ocean absorbs the carbon dioxide (CO2) we produce, and it turns into carbonic acid (H2CO3) in a phenomenon called ocean acidification. As climate change worsens, the ocean becomes increasingly more acidic. As humans disrupt the fragile water chemistry that oysters and other shelled seafood species are used to, it’ll become more difficult for them to survive because they will struggle to develop and maintain their shells.” The shells of the oysters are calcium carbonate. To do this oysters bind calcium, carbon and oxygen from the sea.
We were always told to eat raw oysters in months that end with “r” which would be the fall months of September, October, November and December. These are generally cooler months, but with what is happening to our environment, even our autumn and winter months have experienced warmer temperatures.
With the warmer temperatures in the ocean, a bacteria called vibrio can flourish in the oyster and cause gastrointestinal illness in humans who eat them. Vibrio are naturally occurring bacteria that are in the ocean. With global warming, this bacteria increases. Even if oysters are discriminating in filtering and eating only algae, their filter can also trap vibrio. Symptoms appear 24 hours after eating and can include diarrhea, abdominal cramps, nausea, vomiting and headaches. Symptoms can last up to seven days.
Farmed oysters are safe to eat, even in the summer months, because the water temperature is controlled. The water is also checked for the bacteria Vibrio vulnificus and Vibrio parahaemolyticus. Farm-raised oysters are fed plankton and account for 95 percent of oysters and mussels eaten worldwide.
Warmer waters and a hurricane last September contributed to the proliferation of vibrio along the coast.The Central for Disease Control says that vibrio infections have increased eightfold over the past 50 years, with three people in New York and five in Tampa Florida dying from this bacteria.
The bad thing is it is impossible to tell if an oyster has the bacteria but eating them from Prince Edward Island in Canada where the waters are cooler lowers the risk of the bacteria.
Oyster farming is a clean aquaculture, unlike farmed salmon which have to be fed. This often pollutes the area and causes algae blooms.
According my marine biologist friend Daren Garriques, “Taking wild oysters reduces the natural reefs and lowers the resilience to climate change of coastal areas.” He also said there is usually a state lab that can test the waters and samples of the oysters to certify that they are ok to eat. Farm raised oysters are grown individually and therefore are bigger with more meat and usually a uniform shape.
There are three methods for cultivating oysters:
1. Placing the oysters at the bottom of the bay, which usually gives the oyster a deeper, richer flavor.
2. Floating trays, which gives a lighter flavor.
3. Tumbling when the trays are kept in motion which gives the oysters more muscle and produces a sweeter taste.
One oyster farmer, Hog Island Oyster Company, started their farm with a five-acre shellfish lease in Tomales Bay, California and started with the Pacific oyster (Crassostrea gigas), which is called sweetwater.
Today, they have 250 acres in Tomales and Humbolt Bays, where they raise five oyster varieties and Manila clams. They produce 5 million oysters yearly for the market, have five restaurants featuring their oysters. Six raw oysters sell for $24; 24 sell for $88.
They start from scratch in their hatchery and nursery in Humboldt Bay with the cool, clean water rich in plankton. The oyster grows plump and sweet, and the flavor of the bay is in every bite of each oyster. This is called merroir. This is similar to terroir, which is the taste and flavor of a wine because of its environment in which it is produced.
Oysters are a great source of vitamin A and D, thiamine, riboflavin, niacin and ascorbic acid. Additionally, oysters contain iron, copper, iodine, magnesium and phosphorous.
FYI, oysters for human consumption are in the family Ostreidae while pearl oysters are from the family Pteriidae and are found deep in the ocean.
Email Audrey Wilson at audreywilson808@gmail.com.
