With the onset, or at least the promise, of warmer weather, clam diggers and other shellfish harvesters will have to be aware of the possible presence of red tide in Maine waters. FILE PHOTO

Summer nears with a tint of red

ELLSWORTH — It may still be a bit chilly on the water to be thinking about summer, but at least two signs of its approach have arrived along shore.

Visit any boat yard and hoards of black flies will likely descend within moments of opening the car door.

Look seaward and, according to the Department of Marine Resources, red tide is already abundant in Maine waters.

Last week, DMR announced that the biotoxin season was “well underway” in Maine’s coastal waters. Regional mussel harvesting closures went into effect on May 1 and testing disclosed toxicity in mussels at several locations at that time.

Eastern Maine is showing initial signs of red tide and paralytic shellfish poisoning (PSP), but no closures are in effect beyond the usual regional mussel closures. There is a very active bloom of small cell Pseudo-nitzschia, the microscopic phytoplankton that causes amnesic shellfish poisoning (ASP), in the Blue Hill Bay and Frenchman Bay area. However, testing indicates no toxin is being formed at this time.

In western Maine, DMR has closed several areas to the harvest of all species of shellfish around Harpswell because of the presence of the red tide organism that can cause paralytic shellfish poisoning (PSP). This follows the “normal bloom pattern” for the red tide microorganism.

There is also a clam closure in the Cape Elizabeth-Scarborough area.

Somewhat unusually, this season toxicity has been observed in American oysters. Last Friday afternoon, DMR closed several areas to oyster harvesting including the waters around Bristol and South Bristol as well as the region from Phippsburg to Cape Elizabeth.

The closures affect both wild harvest and farmed oysters, but aquaculturists with leases from the state may file a memorandum of understanding (MOU) with DMR that provides for site specific testing for biotoxins. If the test results are clear, the farmers might be able to continue to harvest their oysters.

The procedure applies only to holders of standard aquaculture leases. Limited Purpose Aquaculture permit holders are not allowed to submit MOUs for site-specific testing.

Recreational shellfish harvesters are reminded to keep track of potential closures because of either pollution or the presence of biotoxins.

The latest information on closures is available through DMR’s biotoxin and shellfish sanitation hotline — (800) 232-4733 or 624-7727 — or by calling the Maine Marine Patrol in Lamoine at 664-2392.

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