This question was posted some time ago but I thought I would go ahead and respond. My maiden name is Jelsma and I have done a lot of research on the Jelsma name and family lines. From my research I have found the origin of the Jelsma name is from the location of Jelsum in Friesland. When Napoleon declared that all families in the Netherlands must declare a family name (surname) many of the names were chosen from places or were chosen as a derivative of another name such as Pietersma was a derivative of Pieters so another train of thought is that Jelsma is derived by combining the name Jelle with -sma to become Jelsma. Either way, when a Dutch surname ends with 'sma' it indicates the origin of the family was in the province of Friesland.