Silence from recruiters means that there is no recruitment going on.

Recruiters are paid on a commission - if there's a vacancy they will do all they can to fill it. If they aren't recruiting in certain sectors, it's because there is no demand.

I hope you don't think you'll be able to come to Doha, visit prospective employers and give them your cv. It doesn't work like that here...

You'll understand when you arrive.