Yes, there were bowling alleys onboard the Norwegain Pearl. They were in the "Bliss" bar/lounge on deck 8. There were 4 lanes paired in two on one side and two on the other.
I did not do any bowling. I think the price was around $5 to $6 per person/ per game. I am not sure if this price included the shoe rental. The alleys looked dark, but the lane and pins glowed purple under the black lights. Some of the other passengers I talked to said the bowling was fun.
No, I did not see any long wait for anyone who wanted to bowl. There were allot of times I saw no one bowling. But I am not sure if that was unusual or not. I did not see any indication of a sign-up, advance reservations, or time limit for the bowling, but I am not sure. They might do those things if there was a long wait to bowl (which I did not see).