A strike by 31,000 retail Stop & Shop supermarket workers is clearly hurting the chain’s short-term financial health, and how the strike is resolved will be critical to the chain’s long-term success.

Workers represented by the United Food and Commercial Workers walked off the job April 11, forcing Stop & Shop to close or curb hours at 240 supermarkets in Connecticut, Massachusetts, and Rhode Island. The two sides had been negotiating since January, and workers had been without a contract since it expired in February.

Historically, the week before Easter has been the third-most-important week of the year for supermarket...