In numerical terms, they should probably stop now. However, far be it from me to point out errors in unscientific, non-evidence-based policies, but we can't actually call this revenge, because the sharks being executed are not the ones which have chomped on human flesh. Actually, we can't even call this collective punishment because, as pointed out by WA Today
Despite the large number of tiger sharks being caught, there has never been a fatal tiger shark attack in WA watersso they aren't even killing the correct species.
The timing of the cull seems odd, as The Guardian notes that
Western Australia’s shark cull has been condemned as futile by international experts as it emerged that attacks in Australia have fallen to their lowest level in five years.As well as tiger sharks mako sharks have been culled, or caught and released in injured states. Wikipedia says:
Most modern attacks involving mako sharks are considered to have been provoked due to harassment or the shark being caught on a fishing line.So I'd recommend not swimming near any beaches where this cull is being performed. According to ABC News swimmers are being given similar warnings when angry injured large sharks are being released near to heavily populated swimming beaches.
Note: Shark attack figures provided by Australian Shark Attack File, Taronga Zoo