With the summer heat unfortunately come the red tide outbreaks along the Maine coast. Although the toxic algae are reason for concern — and cause economic losses — visitors and residents alike should be reassured that Maine’s monitoring program ensures only “clean” shellfish make it to stores and restaurants.
Red tide algae occur naturally in the waters off the East Coast. But during large blooms, shellfish can accumulate potentially toxic levels of red tide while filter feeding. Two factors determine whether an unusual outbreak will occur. If there are lots of nutrients in this area, the bloom is likely to be large. Second, strong currents are needed to carry the algae, which are toxic to humans, closer to shore where they are ingested by shellfish such as clams and mussels.
The resulting sickness, known as paralytic shellfish poisoning, can cause serious illness or death in humans who consume shellfish with toxic levels of red tide.
Consumers should not be concerned about shellfish sold in stores and restaurants. All Maine shellfish destined for commercial markets are tested before they can be sold.
Those harvesting clams, mussels and other shellfish on their own should visit the Department of Marine Resources website to see where it is safe to collect them. Go to www.maine.gov/dmr and click “Red Tide Shellfish Closures.”
Much of the Maine coast is currently closed to mussel harvesting because of red tide, and more closures are expected as summer progresses.
Last year, the Department of Marine Resources closed nearly the entire coast to harvesting for weeks.
A study by Kevin Athearn, associate professor of natural resource economics at the University of Maine at Machias, concluded in 2005 that a statewide, one-week August closure for soft-shell clams, mahogany quahogs and mussels would result in an estimated loss of $1.2 million in harvester sales and a total economic loss of $2.9 million for Maine’s economy.
The losses for last summer were estimated by the Department of Marine Resources to be $10 million.
Red tide is a serious problem for the state’s commercial shellfish harvesters who can lose thousands of dollars when areas are put off-limits. But, those who enjoy a plate of fried clams at the local restaurant have nothing to worry about, and casual harvesters can protect themselves by avoiding all closed areas.