Chum

Effective chumming exploits the extraordinary olfactory sensitivity of fish — sharks can detect blood at concentrations of one part per billion. Chum slicks extend downwind and downcurrent, creating an olfactory highway leading to the boat. Frozen chum blocks (bunker, mackerel, or squid) release scent as they thaw. Ladle-fed ground chum particles create visual and chemical attractants simultaneously. Live chum (throwing alive baitfish overboard) excites predator feeding responses better than dead chum. Shark diving chum slicks have raised conservation concerns by potentially conditioning sharks to associate human activity with food — a debate that continues to generate controversy in shark research and management.