PORTLAND, Maine — The New England shellfish industry faces the threat of widespread red tide outbreaks this spring and summer that could force hundreds of miles of clam flats to be closed and lead to clam shortages.
A survey of the ocean bottom off New England last fall provides evidence there will be a significant bloom of the toxic algae that causes red tide, federal and state officials said Wednesday. This year’s bloom could be similar to those of 2005 and 2008 that shut down shellfish beds from Maine to Cape Cod for months.
Red tide has become more frequent and severe in recent years, resulting in tens of millions of dollars in economic losses. With more red tide being forecast, the outlook is bleak for clam diggers who have had to contend with major outbreaks in three of the past five years.
“It’s going to be devastating,” said Butch Taylor, owner of C&S Seafood in Cushing, which buys clams from more than 100 clammers in the midcoast Maine region.
Red tide is caused by naturally occurring algae that produce a toxin that shellfish absorb as they feed. Red tide taints clams and mussels, making them unsafe for people to eat, but poses no risk to people who eat fish, lobster, scallops and shrimp. Officials stress that clams and mussels on the market are safe, given the regulatory safeguards in place.
Red tide outbreaks have occurred periodically for decades, but some of the worst have occurred in the past five years.
Major blooms in 2005 and 2008 shut down hundreds of miles of shellfish beds in Maine, New Hampshire and Massachusetts. Last summer, nearly the entire Maine coast was shut down at one point.
Scientists each fall survey the ocean bottom to determine the abundance of microscopic cysts that are dropped by algal blooms and act like seeds for future red tide outbreaks.
Last fall’s survey turned up a large number of cysts — 60 percent more than were observed before the huge red tide bloom of 2005 — indicating a large bloom is likely this spring.
The cyst abundance also appears to have expanded to the south, meaning any outbreak could affect areas such as Massachusetts Bay earlier in the season than in past years, scientists said.
The National Oceanic and Atmospheric Administration issued a warning Wednesday about the red tide outlook to give harvesters and aquaculture businesses time to prepare, and restaurants time to make contingency plans for seafood supplies during the summer.
When red tide strikes, clam prices usually go up and retailers and restaurants turn to new suppliers to get product or simply hang out an “Out of Clams” sign, Taylor said. Restaurants serving fried clam rolls typically buy those clams in the spring and freeze them.
Although the conditions point to widespread red tide, researchers say ocean currents and wind patterns ultimately will determine where it shows up and how long it sticks around.
Onshore winds will drive the red tide toward shore and force clam flats to be closed. But when offshore winds are predominant, the algae tend to stay offshore, far away from harvesting areas.
It’s clear that once red tide settles into an area, it tends to stick around for years. But it’s not clear why red tide settles into an area in the first place.
“I think that’s the $64 million question,” said Darcie Couture, who is in charge of monitoring red tide for the Maine Department of Marine Resources.
AP PHOTO BY PAT WELLENBACH
A clammer rakes for quahogs in the New Meadows Lake in Brunswick on Tuesday. Scientists are sounding a warning that the New England shellfish industry faces a potential threat of widespread red tide outbreaks this spring and summer. Researchers say indicators are in place suggesting a significant regional bloom of the toxic algae that causes red tide.