A small percentage were indeed left behind mainly to tend the animals and work the farm but the message could have got a bit tortuous going into the minutia of the Occupation. A few Channel islanders actually ended up in the camps.
Lager Sylt was the main concentration camp that was used by Organisation Todt for Russian and Jewish forced labourers, when they became too ill to work these labourers were 'disposed of' by the SS.
In many, although not all instances, it was a case of collaborate or die - this was true of all the Channel Isalnds, not just Alderney