It is not clear what the origins of oyster stew are. There are as many stories about the beginnings of this savory dish as there are cultures that claim to use oyster stew for holiday celebrations or special meals.
Early history of the use of oysters goes back to ancient Greek and Roman times. Many thought of oysters as an aphrodisiac and cooked and ate them in many ways and in many dishes.
From the Irish?
Some believe that oyster stew was brought to North America when the Irish came to escape the potato famine in Ireland. The coordinator of the Irish Studies Program at the University of Wisconsin-Milwaukee mentions in his writings that they were accustomed to making stew with ling fish, according to an article in the Milwaukee Journal Sentinel. However, upon arrival in America ling fish were not available and oysters seemed to be the closest they could come to a likeness in taste, so they substituted.
According to Diane Morgan in her book "The New Thanksgiving Table" (Chronicle Books, 2009), Native Americans harvested shellfish--including oysters--and most often dried them to store for winter. Historians believe that the Native Americans taught the English colonists and early settlers how to cook them into a stew.
Because it is a "warming dish," many people today use oyster stew for a winter holiday dish. Many use it at Christmas while others use it at New Year's.
There are places from which oyster stew most likely did not originate. For instance, according to Jerry Apps, a professor emeritus at University of Wisconsin, some have speculated that it came over with the Germans because they cook oyster stew for Christmas celebrations. An article in the Milwaukee Journal Sentinel states that this is probably not the case as the waters off Germany are much too cold to grow and harvest oysters.