The Borgata sent a letter to workers Friday afternoon outlining the cuts.
Casino president Melonie Johnson said the cuts were in response to limits that took effect Thursday night under which indoor dining must halt from 10 p.m. to 5 a.m.
The casino is laying off 73 workers and reducing the hours of 349 others.
Bob McDevitt, president of the main Atlantic City casino workers' union, said he did not know of any other casino that had done layoffs since the limits were announced on Monday.
"Regrettably, due to the adjusted operations and overall impact of the pandemic on business, we've been forced to modify our staffing levels," Johnson wrote in her letter to workers.
"We are hopeful to return employees to work and increase hours when the executive order is lifted, operations expand and business demand returns," she wrote. "The governor has not yet announced when the order will be lifted so, unfortunately, we don't know how long this may last and cannot fully assess any lasting impacts on our business levels."
Murphy's order came as the coronavirus rate of infection and number of cases climbs higher in New Jersey and across the country. He said Monday that Health Department officials say indoor settings make it easier for the virus to spread compared with outdoors.
To comply with the order, the casino is closing its restaurants each night at 10 p.m. It also must stop serving beverages on the casino floor, which will remain open around the clock.
In-room dining will be offered all day Saturday and Sunday, and from 4 p.m. to midnight on weekdays.
Laid-off workers will remain on the casino's health insurance plan through Dec. 31.
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