I am genuinely curious where you got your ideas about on perl usage?
Regardless of growth or decline in any of Perl, Python, and Ruby, my opinion is they're so equivalent it's barely worth discussing them separately. Pick the one that has the libraries and frameworks you need. It so happens that http://search.cpan.org is the easiest way to check up on libraries for any of the languages.
Perl6, if they ever pull off a fast and stable release, is another matter. It's likely to be a game changer. I actually quite dislike this perl5i thing and the declarex syntax changing modules in general because they needlessly fragment the language.