Jonathan Winthrop lives in Boston, MA, with his wife Sydney and their two teenage daughters. He has long been dedicated to land conservation and currently manages Joinstock Holdings LLC and Arbella Farms LLC. He is also the past chairman of Groton Land Company, Inc.

An avid salmon angler, Jonathan has been a member of the Moisie Salmon Club for over twenty years and has fished there since the mid-1970s. Recently, he expanded his salmon conservation efforts by acquiring an equity position in waters on the Miramichi River. He has been a Director of the Atlantic Salmon Federation since 1995.