Puppy barking problem!

I am just wondering if anyone can offer advice for a young malamute puppy barking excessively? He is a good little puppy otherwise but the barking is very very excessive and it is grating on everyones nerves...we're a little uncertain how to handle it, as in, we were doing really well (it's my partners pup) and when my partner is at work and pup is left with his family...they tend to encourage bad behaviour, so he has seemingly learnt it now...how can we work around this??
I am aware malamutes by nature are a vocal breed, however almost constant barking is really not acceptable and I'm worried he will continue with this into adulthood

Have you taught him to bark on command yet? If so teach him the quiet command and praise him loads and feed a treat when he stops barking.

Not yet... that's been the last thing on our mind since he barks constantly Right now we can't afford to reward him anymore since it's rewarding him that's gotten us into this mess....ah I don't know :S If he settles he gets something to chew on which will keep him quiet for a while. But we're not able to just give him treats all the time or pay attention to him 100% of the time. He gets lots of attention as a puppy should but obviously there are some times we want him to settle and he's just not content to be doing nothing. I keep thinking he is barking because he needs something, like the toilet, but even when he has been and he doesn't need anything he still barks and he barks when he is tired, so even when he wants to go to sleep he has to bark about it for ages first. Even when we first brought him home, from the moment we got into the car with him he started barking and didn't stop for the first hour until I had him in the back seat with me. I'm just baffled!

Have you tried crating?

Yes he has had a crate from the beginning, he sleeps in there quite happily at night, but during the day if we need a break, and he isn't tired he stands in there and barks and barks (or screams). He has had everything positive associated with the crate, had food, water, treats, toys in there, yet during the day if he is put in there when the people need a break, he acts up, or starts pawing at the bars. He doesn't take himself off to it to sleep either which I thought he would. He is getting walked twice a day and Andy does training with him so it's not like he hasn't had mental stimulation. He is clever - already learnt sit, down and paw, he is just over 3 months I don't know whether this is a boredom/hyperactivity issue or maybe his barking is like kennel barking - mindless and he just does it to pass time or trying to get attention? Thing is when family are baby talking him and telling him in baby voices to settle down and stop barking, it sends the wrong message...but what can you do about other people if they won't listen to what you say??