PORTLAND (AP) – The most toxic red tide to hit Maine coastal waters in decades continued to cause problems as state officials expanded their ban on shellfishing Monday to cover the entire coast.

As of Monday, shellfishing was banned from the Canadian border to the New Hampshire line because of the algae blooms known as red tide, the state Department of Marine Resources said. About two-thirds of the coast had been off-limits Sunday.

There have been no reports of sickness from consumption of tainted shellfish.

The toxins have made several types of clams, as well as mussels, oysters, quahogs, whelks and carnivorous snails, unsafe to eat.

Eating shellfish with high levels of the toxin can cause numbness, dizziness and nausea; in the most extreme cases, eating shellfish with high levels of the toxin can cause muscle paralysis and death.

State officials who announced closures last week are afraid that recreational harvesters unaware of the ban might eat the contaminated shellfish.

A marine patrol officer said enforcing the highly publicized ban over the weekend was not difficult, mostly because of poor weather conditions.

Rain and cool weather Saturday kept most recreational harvesters at home, said Ron Muir, a marine patrol officer assigned to the Mt. Desert Island area. The ban primarily affects commercial harvesters, who were already aware of the off-limit areas, he said.

Muir said he received only one phone call over the weekend from consumers worried about the food they had recently eaten. He said he had not heard any reports of individuals eating toxic shellfish and becoming sick.

“It’s not as big a deal as in the summer,” Muir said. “I mean, it’s a big deal because (toxin) counts are very high. But there’s not as much pressure” to enforce the ban because there isn’t as much recreational harvesting in October as in the summer, he said.

Because shellfish are filter feeders that consume algae, toxic algae blooms can make them unsafe to eat. The blooms produce a neurotoxin – meaning that when consumers eat the contaminated shellfish, the toxin goes straight to their nervous systems.

Red tide closures can last between several days to several weeks. The last significant closures occurred in 2000, when one-third of Maine’s coast was deemed off-limits to shellfishing.