I spent a morning bumbling around Port Cygnet last week for similar result: trolling pulled any amount of cocky salmon - all too small to bother keeping - and bottom fishing several spots there were plenty of flathead, but not one keeper. Water was beautifully clear: see bottom easily in 4metres. Water temp around 15deg C. Haven't tried for squid anywhere for a while, so no idea what's the go with them at present.