Ask a Shark Expert
Read shark researcher Mark Marks' responses on the following shark topics:
Disappearing sharks
Shark evolution
Shark deterrent?
Nonstop swimmers?
Shark posturing
Swimming with the sharks?
Shark diving
Shark education
Shark enemies
Shark reproduction
Great white disposition
Favorite shark
Shark eyes
Shark companions
Bite pressure
Bladderless sharks
Warmblooded killers
Hammerheads
Thresher sharks
Great whites in captivity
Shark protection
Q: On Shark Diving
I have been interested in diving with sharks for a long time, but have always been put off by the story that they throw blood all over you to attract the sharks. Is it true that they do this???
Diane Twiggs
Harare, Zimbabwe
Shark-diving operators typically attract sharks to their boats by laying a sent trail (chum slick), commonly using ground fish such as pilchards or sardines, or pure fish oil. Animal blood has been used in some operations but with varying success. Essentially what happens is that the attractant is either poured or ladled into the water, then the water current and wind carry the chum downstream, where it disperses and forms a scent trail for the sharks to follow upstream. Normally these operations use some form of protective shark cage, from which the diver views the approaching sharks. The attractant used is not applied to the actual divers, although a cage floating at the surface in a chum slick can sometimes leave a nasty taste in your mouth — not to mention an oily film on camera lens, etc. — depending on how oily the chum is. Other shark-diving operators who specialize in open-water dives with free-swimming sharks may use a frozen block of chum (a "chumsicle"). This method works like a time-released slick, spreading as the chum melts. Regardless, if you are interested in this type of activity, inquire about the methods used to attract the animals. Personally, I'm not in favor of businesses where exciting the sharks with bait facilitates shark viewing. Dive enough and you'll eventually be rewarded with a natural encounter; these are often the most memorable experiences in a diver's logbook!
