I know this can be done in one line with a regex and someone will probably blow my solution out of the water)but

my $x=">gb|AE004895>gb|TTGGT>gb|";
my @gene= split(/>gb\|/,$x);
foreach my $tmp (@gene)
 {
   if($tmp =~ m/\w+/)
    {
     print "Length"."=".length($tmp)."\n";
   }
}
[download]

use split on the ">gb|" delimeter ."|" is a special char so escape and use length
HTH