Yep, those are scale insects.
There were quite a few on our young fruit trees a few years ago, though not as intensive as you seem to have. This stationary phase is the mother, settling into one place to hatch out a batch of young. I used to go around with a small stick and scrape them off the branches I could reach in May. They had a yucky squishy snot blob inside. By June here, they had dried up and would just crumble off, so I think I have to do it in May to have any effect; I think in June the young have hatched out and left already. I asked a friend who has a diverse organic farm from his ancestors. He said he'd never seen such a thing. We looked up and noticed they were on the twigs above us. He gets large harvests every year of apples and apricots and other fruits, so I guess the scale insects don't harm the trees
enough to worry about unless they seem to be getting out of hand.
They supposedly weaken the tree but do not do anything specifically to the fruit, so I figure I'll scrape off the ones I can reach if I happen to have time in May, but otherwise, I'll let the ecosystem keep them under control.