BBB pg 29. Fighters Vs ordinance markers: remove both the defending and attacking markers from play.
Torpedoes reguardless of size are always one marker (BBB pg 28. The higher the strength, the larger the salvo and the larger the marker placed to represent the salvo.)
so, in essence, torpedoes are completely worthless as soon as the enemy has a single carrier, since then he can kill 4 large salvoes each turn. sounds SLIGHTLY unbalanced to me... 
and that means ships with a single fighter on CAP are invulnerable to torps? serously, wtf?
we have played it always as one fighter removes one torp strength, that might be a bit low, yeah, but one lonely fighter removing a str9 salvo (or even higher with combined salvoes)? i mean, how?? 
First of all, we're not talking about a single fighter. A marker represents a whole group of them.
Second of all - if enemy has single fighter on CAP, first you fire a small torpedo salvo at him [single torpedo from Falchion or Defender comes to mind], he has to waste his fighter, than the huge salvo moves in. Remember - you decide order in which your torpedos move. If you use it wisely, you'll be able to make enemy use all his fighters on worthless 1-2 strong salvos.
In his turn, however.. yep, if you left those 9 torpedos flying in the enemy turn in range of his carriers, the salvo is lost. Due to your mistake, though.
It's not unbalanced, really, it just requires some forward planning. The trick is to have ships firing both large and small amounts of torps, to bait fighters away from the proper targets.
Also, these are some nice torpedo markers... I'll have to think about something similar...