Aug 11, 2016Climate change is responsible for a number of threats to the U.S. shellfish industry. In recent years, Washington State's $270 million shellfish industry has been scrambling to address productivity losses due to ocean acidification, caused by a significant increase in carbon dioxide emissions that began at the start of the industrial revolution. In highly acidic water, it is difficult for shellfish larvae to create shells from calcium carbonate because the water is too corrosive. In 2007 and 2008, Pacific Northwest shellfish larvae hatcheries saw their output plummet by up to 80 percent. By enacting strict water pH monitoring practices, these hatcheries have largely recovered, but the larger seafood industry is under threat as oceans continue to acidify, which threatens the health of wild shellfish as well as coral, which are vital parts of oceanic ecosystems.
Now, new research has illuminated another climate-related threat to the shellfish industry. The study, published this week in the Proceedings of the National Academy of Sciences, documents a link between warming seawater and an uptick in Vibrio bacteria. Humans who come into contact with these bacteria through various pathways, such as by consuming raw oysters that harbor the organisms or by swimming in water in which the bacteria live, can become very ill if the bacteria are present in high densities.
The study, entitled Climate Influence on Vibrio and Associated Human Diseases During the Past Half-Century in the Coastal North Atlantic provides empirical evidence that a change in water temperature is the cause of the growth of Vibrio, but the correlation has long been suggested by medical evidence. According to an Associated Press article about the new study, the Centers for Disease Control and Prevention reports that lab-confirmed Vibrio infections in the United States have increased from an annual average of about 390 in the late 1990s to 1,030 in recent years—and in those recent cases, an average of 100 infections per year prove fatal.
For a number of years, the U.S. Food and Drug Administration (FDA) has been considering requiring oyster producers to sterilize oysters pulled from the Gulf Coast, due to an increase in illnesses reported in that region, especially during the warmest months. In May, a consumer group filed a suit against the FDA, saying it is moving too slowly toward setting stricter regulations on oyster growers. But the East Coast Shellfish Growers Association (ECSGA) strongly resists any efforts to force growers to adopt sterilization techniques, even if only during part of the year and only along the Gulf Coast, on the grounds that this would diminish U.S. producers' competitive advantage.
On its website, the ECSGA posted the following: "As an industry our fear is that this is a slippery slope and the FDA really wants to mandate sterilization of all shellfish. This would open the door to cheap, sterilized shellfish from Asian nations where shellfish are grown in filth. Our only market advantage is that we can offer fresh live shellfish – once we lose that advantage our markets will evaporate."
Some shelfish growers are studying how they can mitigate their challenges through use of wireless sensors. Daniel Ward, an entrepreneur and researcher who operates a 10-acre aquaculture operation in Megansett Harbor, on Massachusetts' Cape Code, is experimenting with thermal cameras and temperature trackers, communicating over a cellular network provided by Verizon, to track the temperature of his oyster harvest—specifically to address the threat posed by Vibrio bacteria (see Massachusetts Oyster Farmer Putting IoT to Work).
Vibrio—particularly two types, Vibrio vulnificus and Vibrio parahaemolyticus—are not being introduced to Ward's farm due to climate change. They've always been present, though Ward told me that they proliferate when the water at his farm is warmest. But as long as the oysters are chilled to 45 degrees Fahrenheit (7.2 degrees Celsius) as soon as possible after harvest, and are then kept at that temperature until they reach the consumer, the danger is removed.
"When water temperature is increased and then there are shipping failures, people get sick every year," Ward said (referring not necessarily to oysters from his farm, but rather the consumption of raw oysters in general).
The technology that Ward is piloting might prove effective in keeping his customers' customers healthy, and his business growing. If it does, others in the industry might take the same or similar approaches to tracking the temperatures to which oysters are subjected.
"I'm looking for ways to make aquaculture more economically and environmentally viable," Ward said, "through better output and better tech."
If Ward and oyster growers can show that more precise monitoring, through the use of wireless sensors and other IoT technology, can insure that their products are safe for human consumption, perhaps they will be able to avoid sterilizing oysters and maintain their farm-fresh advantage.
