Regulators on Tuesday voted to cancel the 2014 shrimp season in the Gulf of Maine, the first such shutdown since 1978. Before the vote, the Atlantic States Marine Fisheries Commission’s Northern Shrimp Section cited research that shows stocks of shrimp are at historic lows, because of factors such as overfishing and warming waters. The fishery for northern shrimp, also called pink shrimp, was worth an estimated $1.2 million in its limited 2013 season; in 2011, according to regulators, it was worth more than $10 million.