Shellfish Problems Are Another Sign of a Warming Sound

Oyster boats tied up in Norwalk.

The recall and the closure are directly linked to warmer water temperatures.

The recall of Long Island Sound shellfish, and the closure of shellfish beds off Norwalk and Westport, received a fair amount of attention this week, but one overlooked aspect is that the problem is probably yet another sign that the Sound is growing warmer.

The recall affected shellfish harvested from late June through July off Westport and Norwalk, prime oyster territory in the Sound, after health officials discovered the dangerous Vibrio parahaemolyticus bacteria in the water.

The closure affects shellfish beds that are in 20 feet of water or less. Those beds will stay closed until September.

Although there was a Vibrio outbreak several years ago in Rhode Island, and one last summer on the north shore of Long Island, this was the first outbreak in Connecticut. Here is the Connecticut Agriculture Department’s news release about this year’s recall, and you can read news accounts here and here.

Vibrio is not related to sewage spills or contaminated stormwater. It is a naturally-occurring, warm-water pathogen, common, for example, in the Gulf of Mexico. Widespread outbreaks were previously unknown here because Long Island Sound has always been too cold for it to flourish.

No longer. But no one observing natural events in the Sound should be surprised.

Lobsters, a cold-water species, no longer flourish in the Sound. Last summer, the Millstone nuclear power plant in Waterford had to shut down because the cooling water it draws from the Sound was too warm to do the job. And also last summer, two Connecticut scientists published a paper demonstrating that warm-water fish were slowly but surely replacing cold water fish in the Sound.

Now Vibrio is here. What it means for the future of the Sound’s shellfishing industry in summer remains to be seen.

Posted by Tom Andersen, New York programs and communications coordinator, and Laura McMillan, director of communications, for Save the Sound