squid will catch most species of fish,a tip i learned from a local at anst'er many years ago was to leave the squid out for at least 3 days to smell even more before using as let's face it most bottom feeders would only be eating squid that's been dead for some time.
i went up to scrabbie years back for a weeks holiday shark fishing booked a cottage at dunnet head(aga cookers peat heating)put my squid in the freezer on saturday blew a gale till wednesday then i opened freezer to get the squid out almost puked ,it was faulty, never on! fermenting away for days!, anyway had to get out ,charters wouldn't go out but local potman(english guy!) offered to take me out in his 16ft open boat just out into the bay for 2-3hrs he reckoned his 3 hook ripper set up would well outfish my mankie squid, i didn't take much squid up it was only to catch enough shark bait so i cut it up into small 1" strips fished on a single hook long trace skipper caught 8 cod i caught 23! even in defeat he refused my offer to pay for the fuel,nice people up there! pity about the weather but the fishing makes up for it!
i also used double squid on pennels to catch double figure cod! it's also a bait that refreezes well(as if the fish gives a toss!) so it's very economical,tough enough for casting and resisting crabs so use it!