Hello Claudia,
My name is Niek van het Kaar, although I was born and raised in Eindhoven, Noord Brabant I am living and working in the US for about 20 years now, yikes, time flies when you have fun. Anyway, according to what my dad told me the name "Kaar" is the basket to keep the fish alive after catching it, sounds familiar, and that the name originates from Noord Holland. Somewhere in my parent's home there is a Kaar family tree which my father started, next time when I am in the Netherlands I'll see if I can find it and scan it into a file. Daag.