Red tide may make swimming unpleasant, but is it really a health hazard? Only if you make your own Shore Dinner, say tide experts.
What we call red tide is actually a "bloom" of algae in our waters. Most red algae species are not hazardous to swimmers, but a few pose a threat to shellfish eaters. Shellfish, including clams, oysters, quahogs, mussels and scallops, filter the water around themselves in order to find food. In the process, they may ingest algae that is harmful to humans. The algae's toxin becomes concentrated in the shellfish. A single oyster can filter up to 7 gallons of water per hour. Non-filter feeders, such as lobsters, crabs and shrimp, are not affected by red tide blooms.
In New England, shellfishing waters are routinely screened for dangerous levels of the algae, and strict laws prohibit fishing in algae-prone areas. Digging for shellfish in illegal areas carries hefty fines and potential health risks. If the red tide is especially thick, beaches may be closed to protect swimmers.
The best advice is that if you are unsure of where a shellfish has come from, don't eat it. No amount of cooking will make it safe.
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