my %data = (
    foo1 => [
        '1 - 201 - 229',
        '2 - 201 - 229',
        '3 - 201 - 229',
    ],

    foo2 => [
        '1 - 201 - 218',
        '2 - 201 - 218',
        '3 - 201 - 218',
        '4 - 201 - 218',
        '5 - 201 - 218',
        '6 - 201 - 218',
        '7 - 201 - 218',
   ],

# . . . 
);

##</code><code>##

my @act_bsites = @{$data{$dataset}};

##</code><code>##

# file: /path/to/foosites
{
    foo1 => [
        '1 - 201 - 229',
        '2 - 201 - 229',
        '3 - 201 - 229',
    ],

    foo2 => [
        '1 - 201 - 218',
        '2 - 201 - 218',
        '3 - 201 - 218',
        '4 - 201 - 218',
        '5 - 201 - 218',
        '6 - 201 - 218',
        '7 - 201 - 218',
   ],

# . . . 
};

##</code><code>##

my @act_bsites = @{(do '/path/to/foosites')->{$dataset}};