TranspacBlogII-10: Ok this really is the last shark blog.

Sharks really are amazing creatures. I give a shark lecture in my zoology class. It is a pretty popular lecture. Rob Rebstock's experience is one of the substories (see II-8), but there is another cool shark story that I tell my students. I heard this story from a young professor of vertebrate biology, Jim Ha, whose father was a famous shark expert from Hawaii. Now I'm not sure who was studying what, but the Navy had this problem of how to keep downed jet pilots alive in a tropical sea. This problem came to a head when helicopter rescue pilots reported again and again the following scenario. After many hours, even days of searching, a rescue helicopter would finally sight and fly over the downed pilot, who was usually actively waving at them. Shockingly, by the time they had circled around to pull the pilot up to the helicopter, they often pulled up only half a body, the rest of it was apparently in some sharks. This all seemed too bizarre until they consulted Jim's father, or perhaps one of his associates. Recent research on sharks had explored how their lateral line system worked. Now the lateral line of sharks and other fish is how these animals detect vibrations in the water.

http://science.howstuffworks.com/shark2.htm

It is essentially a trough that runs down each side, filled with exquisitely sensitive hairs that are tuned to important vibrations. One of these is the sound of a wounded fish. I don't know how many of you have ever spear-fished, but even if you haven't, you can imagine how an severely injured fish swims away. Say "thup-thup-thup-thup" as fast as your mouth will let you, and that is about how fast an injured fish swims away. So it shouldn't be surprising to find out the lateral line of sharks is highly tuned to that particular sound. Furthermore, a shark that hears that sound will be readying itself to eat.

Now go in your mind back to the downed fighter pilot, who has miraculously survived days in the ocean. He has seen sharks, but none have attacked him. Then he sees the rescue helicopter in the distance, perhaps simultaneously with his hearing the familiar sound of a rescue helicopter's roters. "Thup-thup-thup-thup". Next thing he knows all the sharks within miles of him are zeroing in for the kill. That's about it for him.

So, what did Dr. Ha suggest? Change the frequency of the rotors when you sight a person in the water. They simply changed the pitch of the rotors so they went with a "whirr" instead of a "thup-thup-thup-thup", and the problem was solved!

Now this is the story I heard from Dr. Ha's son, Dr. Jim Ha. But the more I think about it, the more skeptical I've become. I've got an email into Jim, so I'll let you know what he says. Perhaps he will comment on this blog (hint, hint)!

Anyway, this story adds one more thing to worry about if you're lost at sea. The rescue helicopter itself. Hopefully, they've taken the proper measures, and your shark friends don't become foes.

Finally, if all of these ravings about man overboard and sharks seem to be those of a guy with an overactive imagination, consider the 1951 Transpac Yacht race. 800 miles short of Honolulu, in stormy tropical seas, the second-place boat, L'Apache, a 73-foot cutter, lost crewmember Ted Sierkes overboard. Now this seems like a long time ago, but I remember seeing the sail-master of the L'Apache, a remarkable woman named Peggy Slater at various regattas etc (she should be the subject of books, much less blogs). Knowing who she is connects me personally to this story. Peggy and the rest of the L'Apache were UNABLE to find Sierkes, so virtually all of the front runners (famous boats like EVENING STAR, and SKYLARK) stopped the race and joined the hunt for this poor guy. They didn't find him. He floated in the tropical waters for 29 hours, by which time he was 50 miles from where he fell overboard. Lucky for everyone, but especially Ted, a navy destroyer, one of several vessels (including a helicopter; think about that!) involved in the search, actually found this poor guy on the verge of death. He survived, and had some interesting things to say about the experience:

About having given up, and just wanting to die (I wonder if he might be a descendent of the Berra lineage): "It's hard to drown when you know how to swim."

About being attacked by a shark: "I grabbed his tail, flipped him over and ripped up the belly with my knife."

About his thoughts while he treaded water: "I thought about how I was messing up the race for a lot of people."

About what to do, now that he actually survived this ordeal: "Now that I've been rescued, I figure there must have been a reason. There must be something for me to do. I'll have to try and find out what it is."

This last quote leads to a post-script; whose significance is not lost on me or any other person who sails in blue water; two years later, Ted Sierkes tripped and fell in a freak accident and died on the spot.