Captain Jo was an Indigenous person who lived with about 160 other Indigenous people along the Mousam River in what is now Kennebunk.

"The whole number who lived in this town was about one hundred and sixty. They were not of the same tribe. The king of one part of them lived on Great Hill. His name was Tom Wawa. The chief personage of the others, of what rank I do not know, was Captain Jo, who lived in one of the wigwams on Mousam river. These wigwams were not their constant places of abode. It is well known that during the colder part of the season, the Indians retired to the interior of the country. A portion of them spent the winter at Pigwacket [aka Pequawket, near the headwaters of the Saco River/Fryeburg], some of them at Norridgewock [in central Maine, on the Kennebec River], others went as far as Canada. Those who have survived until within a few years could recount the names of all of the Indians who lived within their neighborhood, with as much familiarity and certainty as those of their own kinsmen and friends." - Bourne, pp. 47-48

Bibliography:

Ancient History of Kennebunk, Written in 1831 - Edward E. Bourne