is a shared pointer to std::thread a bad practice?

Does it make sense to use std::shared_ptr < std::thread> ? The logic is simple: if thread is not needed, delete it, if new is required - realocate it. is there any way to compare this concept with pooled threads?

I do know the exact ammount of threads in my system(I develop Image processing algorithm, and I wanted to give each child of "algorithm" class an individual thread (maybe to make it private, then no shared_ptr is required), where this algorithm will be running, and idle this private thread if no image was provided. Is it a bad concept?