The Secret Life of Sharks by A. Peter Klimley, Simon & Schuster, $25, ISBN 0743241703 Reviewed by Arthur A. Myrberg, Jr
PETER Klimley swims among sharks for a living. At least, when he wanted to know what it was about killer whales that made sharks flee, he challenged them.
He donned an appropriately coloured costume and performed a 鈥渄olphin-kick鈥� manoeuvre to mimic a killer whale. Those tempted to try this in similarly close vicinity to sharks should know that his efforts were for naught: the sharks were unmoved.
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Klimley, a researcher at the University of California at Davis, is a world expert on the behaviour of sharks, and The Secret Life of Sharks is his autobiography. His professional interest in trying to understand the behaviour of sharks began in 1973, when he chose to study at the University of Miami鈥檚 School of Marine Science.
Having ruled out the appearance of killer whales as a deterrent to sharks by the courageous means described above, Klimley was left to wonder what properties of a killer whale鈥檚 sound 鈥渇rightens鈥� sharks. He describes his methodology for studying adult lemon sharks in much detail. Indeed, some readers may want to gloss over the fine detail 鈥� but those interested in his numerous experimental methods will appreciate it. His results clearly showed that it was not the killer whale鈥檚 sound per se that repelled sharks.
Almost any intense and sudden sound within 10 metres of a shark will cause it to beat a hasty retreat. So sharks react much like any other vertebrates 鈥� and, like others, they soon become accustomed to repetitive signals and once habituated ignore them.
Another of Klimley鈥檚 great research interests is sharks鈥� schooling and migration. Why do hammerhead sharks form organised schools that can number in the hundreds over certain seamounts in the Gulf of California? Why do they choose some seamounts but not others? How do single individuals rapidly find their way back, over many miles, to a specific seamount after leaving it for hours?
His account of this work is also loaded with stories about free-diving among them, as well as his developing hypotheses and theories. He does a good job of conveying the vicissitudes of research and the problems faced when attempting to use free-ranging sharks as subjects for goal- directed research.
And, of course, what do sharks eat? The so-called man-eaters, the Great White sharks found in the waters off central California, in fact prefer seals and sea-lions. Klimley speculates that they may well be such finicky feeders that they can distinguish between fat and relatively lean bodies with the first bite. His close observation has also led to the idea 鈥� not accepted by all 鈥� that their 鈥渢ail slap鈥� manoeuvre conveys a Great White鈥檚 dominance over fellow sharks.
Sharks are not, of course, as dominant over their environment as myth may suggest. Klimley makes it clear how overfishing can and will rapidly deplete their numbers and The Secret Life of Sharks concludes with a plea for their conservation. I highly recommend this book to those interested in sharks as well as any reader who wishes a journey to an exciting world with a fine writer as their guide.