In Print : The shark
The Shark Handbook, by Dr. Greg Skomal, Cider Mill Press, Kennebunkport, Maine, 2008. 275 pages.
Sharks as we know them today started swimming in the world's oceans some 400 million years ago. That they have changed so little over the millennia is the first remarkable thing, but hardly the last, that we learn in The Shark Handbook, by Greg Skomal, with photos by Nick Caloyianis.
At 7:30 tomorrow evening, Mr. Skomal will discuss his book at the Bunch of Grapes bookstore in Vineyard Haven. "I'll talk about the goals of the book, about bridging the gap between science and the public," he said this week, adding that he looks at the event as more of a conversation than a presentation.
Mr. Skomal, who lives and works in Oak Bluffs, is a senior fisheries biologist with the Massachusetts Division of Marine Fisheries. He runs the state's Shark Research Program and consults on shark research worldwide. In addition to multiple trips to shark hot spots in this hemisphere in 2009, he has been as far afield as Saudi Arabia where he spent 10 days in March tagging whale sharks in the Red Sea.
Whenever there's an unusual shark event in local waters - like the gang of great whites that hounded seals off Chatham late this summer or the huge basking shark that washed ashore in Aquinnah in June, Greg Skomal is not far behind - tagging, photographing, dissecting.
The first half of the Shark Handbook is devoted to shark characteristics in general, with chapters on evolution, anatomy, life history, and conservation.
Perhaps because of the mystique built up around them, sharks sometimes seem like separate creatures, neither fish nor mammal, and the author makes great strides in demystifying them. In fact, they are fishes, but with many unique characteristics that have made them exceptionally well adapted to their habitat and their purpose.
Their cartilaginous skeletons are lighter and more flexible than those made of bone, which improves mobility and speed. Their spines extend well into the upper lobe of the caudal, or tail, fin, the primary source of propulsion. Their bodies are covered with very small scales, called denticles, which make them very slippery when they are moving forward. They don't have swim bladders, which most fish rely on for buoyancy, and they can sense extremely weak electrical fields that emanate from prey species. Finally, they are very strong, with muscle comprising more than 60 percent of their bodies.
So why, given all these wondrous evolutionary adaptations, don't we admire and revere sharks? Well... it's about the teeth, isn't it? "The business end of a shark is its mouth - there is probably no maw on the planet that is more feared, " writes Mr. Skomal. "Lined with multiple rows of sharp teeth, the jaw of a shark is an efficient tool for biting, chomping, slicing, and crunching."
Because most sharks are open ocean fishes, they can be very difficult to study. Some species travel thousands of miles: basking sharks summer off New England and range as far south as Brazil in winter. Others dive to incredible depths, and still others swim very fast - up to 40 miles per hour in the case of makos.
In the last 50 years, tagging studies have provided a dramatic increase in the amount of information about sharks. The world's largest and oldest tagging program, based in Rhode Island, is the National Marine Fisheries Service Cooperative Shark Tagging Program. More than 8,000 participants - commercial and recreational fishermen, biologists and observers - have tagged more than 200,000 of 52 species of sharks since the program's inception in 1962. Mr. Skomal has been involved with the program since 1983, for several years as a full-time employee and for the last 20 years as a collaborator. Currently he is comparing the data collected by early, rudimentary tags and their more sophisticated descendants.
The former would simply record the date and location of the initial tagging and capture, providing a bare-bones picture of a fish's movements. Nowadays, electronic "tags" can continually transmit richer data - three dimensional movement and water temperature, for instance - directly to the laboratory via satellite, or even to a laptop computer.
Sharks have come under increasing pressure from both recreational and commercial fishermen in recent years, and the population of some species has plummeted dangerously. "We now face the greatest level of shark exploitation by humans in history," Mr. Skomal writes. "Without international management and conservation, the 450-million-year history of these animals can come to an abrupt end."
No shark book would be complete without a discussion of shark attacks on humans, and Mr. Skomal complies, although somewhat reluctantly. First, he points out that the odds of getting attacked are miniscule and, second, it strikes him as blindingly obvious that common sense is the best insurance against an attack. You don't swim alone where and when sharks are known to feed, for example.
The second half of The Shark Handbook is devoted to descriptions of more than 400 species of sharks. For three dozen of them, Mr. Skomal provides a brief overview and then specific information on identification, size, distribution, habitat, behavior, reproduction, feeding, and population status.
The book is full of compelling, informative photos, most of them taken by Mr. Skomal and Mr. Caloyianis. Topped off with some 50 pages of appendices, it all adds up to a ton of information in a small package.
This volume should delight both the merely curious and the shark-heads among us. Throughout, the tone and delivery is at once authoritative and accessible. The subtitle, "The Essential Guide for Understanding the Sharks of the World," is no exaggeration. On all counts, The Shark Handbook is a bull's-eye, and Mr. Skomal and Mr.
Caloyianis should be proud indeed of what they've produced.
Book Discussion. Friday,October 16, 7:30 pm. The Shark Handbook, by Greg Skomal. Bunch of Grapes bookstore, Vineyard Haven.