Must one use the © symbol on a book's copyright page when using a CC license?
Is it necessary to say copyright on the "copyright" page when using a Creative Commons (CC) license?


It's not "necessary" but it is a good idea. This communicates the information that there is a copyright holder for the work and the copyright holder is licensing the copyright under the terms of the CC license. Using the CC license does not negate the existence of a copyright on the work; in fact, it is only by virtue of having a copyright on a work in the first place that you can license it to others under the CC license if you so wish.

In most jurisdictions (Berne convention), copyright is "automatic" and it is not required to claim a copyright in any particular form. However, people who might otherwise use your work as permitted by the CC license may be put off if your legalese is missing or unconventional.