Officials hope manual will help lifeguards, beachgoers confirm shark sightings

By Sarah N. Mattero, Globe Correspondent

Every time something fin-like slices through the water off a Massachusetts beach, a question races through everyone’s mind: What the heck was that?

Now officials at the Cape Cod National Seashore and the Massachusetts Division of Marine Fisheries are hoping to provide some answers -- by compiling a manual to help lifeguards and beachgoers identify what they have seen.

The manual, with the working title “Marine Mammal Reference Manual,” is only in the planning stages but officials hope to complete it in a few weeks.

Shark concerns have been growing in recent years, with an increased number of great white shark sightings, particularly in areas off the Cape frequented by seals, a favorite food for the animals. Last Monday, a Colorado man needed dozens of stitches after being bitten in the legs by a great white shark while swimming with his son off Ballston Beach in Truro.

The national seashore has been contacting other national parks across the country for help with the manual, particularly the Golden Gate National Recreation Area in California, which often deals with great white sharks in its waters, said Leslie Reynolds, the seashore’s chief ranger.

The manual will include multiple marine animals, helping people to distinguish great white sharks from other harmless animals that people can mistake them for, including basking sharks, sunfish, dolphins, whales, and even birds, Reynolds said.

The officials don’t expect the manual to turn into an all-encompassing encyclopedia, but a good reference for what people may encounter in New England waters.

Along with the reference manual, there will be a questionnaire for the public to fill out after shark sightings, said Reynolds.

The national seashore is also finalizing their manual for response to shark or other animal attacks, she said.