backPAN modules still appear in CPAN search results?

Hi,

I'm one of the core developers for the BioPerl project.

We've had a persistent problem with users grabbing outdated versions of 
our distributions from CPAN. For example, the distribution 
bioperl-1.4.tar.gz is deprecated and is on backpan, as seen here:

     http://backpan.perl.org/authors/id/B/BI/BIRNEY/

and yet in a search for bioperl through the cpan command-line interface, 
bioperl-1.4.tar.gz turns up almost at the top of the list:

cpan[2]> i /bioperl/
Bundle    Bundle::BioPerl        (CRAFFI/Bundle-BioPerl-2.1.8.tar.gz)
Distribution    BIRNEY/bioperl-1.4.tar.gz
Distribution    BIRNEY/bioperl-db-0.1.tar.gz
[..snip..]
16 items found


Is there a way to prevent our old distributions from appearing in CPAN 
search results?

It would be fine, for example, if they were removed from CPAN and 
BackPAN completely (we have them archived elsewhere).


Thanks for any guidance,
Dave