NARRAGANSETT -- Last summer, a surfer and an off-duty lifeguard spotted six sharks off the Narragansett coast, prompting officials to close the Town Beach to swimmers. Beach goers spotted more sharks the next day.

But not everyone agreed on what kind of sharks skirted the shore. Were they smooth or spiny dogfish sharks? Tiger sharks? Or maybe even sunfish?

A new book, edited by two local experts, may help.

The 118-page Guide to Sharks, Tunas & Billfishes of the U.S. Atlantic & Gulf of Mexico, published by Rhode Island Sea Grant and the National Marine Fisheries Service, includes photographs, descriptions and key characteristics of 44 fish, from the thresher shark to the longbill spearfish.

The guide, two years in the making, was "well under way" before the Narragansett shark sighting, says Tony Corey, with Rhode Island Sea Grant at the University of Rhode Island's Narragansett campus.

It differs from other guides by providing plenty of photographs of sharks in the water.

The publishers want fishermen, boaters, scientists and others to be able to recognize sharks and other fish without having to first catch -- and possibly harm -- them.

"This will allow people to identify the fish before they bring it aboard," says Guide editor Maro Schulz-Haugen, a management specialist with the National Marine Fisheries Service in Maryland. "We want to afford the fish as much protection as we can."

Finding photographs of sharks in the water was a challenge, says Corey, one of the guide's editors. "Photos are hard to come by. These animals are protected because they're rare or sparsely reported or poorly understood."

The spiral-bound guide, priced at $25, is waterproof. It includes glossy pages marked "Sharks at a Glance" and features color-coded sections for quick reference.

It also includes tips on how to avoid shark attacks and how to handle and release injured or entangled dolphins, porpoises and seals.

According to the guide, sharks -- with rough, sandpaper-like skin -- can range from 8 inches (pygmy shark) to 40 feet (whale shark). Using a keen sense of smell, and eyes that can adapt to dim light, they can detect prey buried in the sand.

Last July, swimmers saw sharks about 150 feet from the Narragansett Town Beach. The next day, beach goers reported more sharks, although some experts said they may have been sunfish.

Nancy E. Kohler, one of the Guide's editors, thinks the fish were probably dogfish sharks.

"When the weather gets warmer, and there are large crowds on the beach, we'll probably see them again," says Kohler, chief of the Apex Predators Program in Narragansett, part of the National Marine Fisheries Service.

Sharks aren't uncommon in Rhode Island. During the summer, they move from Florida and the mid-Atlantic to the Northeast in search of warm water and local fish. Deep-water species include mako, blue and thresher sharks.

They don't all resemble the man-eaters in the book and movie, Jaws.

One of the largest, the whale shark, is a filter feeder; it strains small organisms from the water through thousands of tiny teeth.

"They are not all dangerous and man eaters," says Schulz-Haugen. "There are 400 species of sharks, from itty-bitty 8-inch deep-water sharks to the 18-foot tiger shark. But the vast majority don't interact with humans."