A live baby great white shark was brought into Menemsha harbor by a local fishing boat Tuesday morning. And though the fish was only five feet in length, the fact that it was a great white caused quite a stir.

Capt. Gregory Mayhew and his son Jeremy went out fishing in the morning to catch fluke. They were in Unicorn, a 75-foot steel western-rig fishing boat about two miles off the green buoy outside of Menemsha, when they hauled back their net and the shark came aboard. Captain Mayhew said initially they thought they had caught a porbeagle, an edible species of shark.

When the vessel came into the harbor, it was another Menemsha fisherman who knew it was the rarer great white.

Karsten Larsen identified the fish. Mr. Larsen is a swordfisherman and frequently spends a lot of time far offshore.

When they realized what it was, the Mayhews moved the shark from out in the air to a pen, and filled it with seawater. The great white baby recovered. Within a short time, people were gathering around to see it. The Unicorn was tied up next to the Quitsa Strider II, a fishing boat owned by Gregory's brother, Jonathan.

With the help of the harbor master's office, Captain Mayhew used a telephone to talk to scientists in Woods Hole. Captain Mayhew wondered at the time whether these scientists wanted it for an aquarium.

He had a conversation on the telephone with Greg Skomal, of the state Division of Marine Fisheries, who happened to be in Delaware at the time. Mr. Skomal, who is the state's shark expert, advised the fishermen to release the fish after positive confirmation that it was indeed a great white shark.

Jeremy Mayhew told the Gazette yesterday they released the shark back into Vineyard Sound near the Elizabeth Islands.

Mr. Skomal said: "Yes, it was absolutely a great white shark. I was able to send my friend and volunteer Jesse Fuller of Oak Bluffs to take digital pictures of the shark and e-mail them to me in Delaware Bay. Due to the quality of the images, I was able to identify it."

Mr. Skomal said the shark was probably about a year old.

"It is an extremely rare species. We do not see a lot of these fish. We know they swim in New England, but it is unusual to see one," he said.

Mr. Skomal said the great white shark is a federally prohibited species, which means you can't possess or catch it. Other prohibited species include long-fin mako, dusky shark and basking shark. "There are a dozen sharks that are prohibited. The reason they are prohibited is precautionary. We may not have enough information to establish that a certain shark population is declining, but as a precautionary measure a number of species are listed as prohibited," he said.

"The first question that I am always asked about small sharks is: ‘Where is the mother?' " Mr. Skomal said. "Let me say first that there is no parental care in sharks. Shark mothers don't care for their young, nor do they care about them. Once that baby is born, it is on its own.

"Sharks are highly migratory. The mother probably gave birth in the tropics," he said.

Great white sharks are a rare fish in the Atlantic. "We know there are great white sharks off south Australia, South Africa and the coast of California. Those are the hot spots for great white sharks, where attacks are most frequent," he said. "In the Atlantic the shark is enigmatic. We don't have access to the animal in predictable ways."

And that is why the movie Jaws attracted such public interest. "We know that great white sharks grow to 18 to 19 feet in length. The longest ever measured was 21 feet."

Scientists know that great white sharks do have a range in the Atlantic and are most likely caught in the summer between Cape Cod and North Carolina.

Each summer the Boston Big Game Fishing Club hosts the Oak Bluffs Monster Shark Tournament in July, and in the last 16 years no one has ever caught a great white. They've caught blue shark, thresher and mako sharks, and the list goes on.

What do great white sharks eat?

"We know in southern California they feed on marine mammals like seals and sea lions," Mr. Skomal said. "The reason why someone usually gets bitten is that they are mistaken for a seal. In the Atlantic they don't seem to work intensely on marine mammals. We think it is very different. We think that great white sharks feed on dead whales," Mr. Skomal said.

"We know that juvenile great white sharks feed on bluefish and other schooling fish. When they get to be big enough, they eat larger animals. They don't want to eat popcorn when they can afford something bigger. We think it is dead whales," Mr. Skomal said.

Should anyone be concerned about shark attacks? Mr. Skomal said he heard about the dead whale that washed up on South Beach Monday. "My concern is that when you put a dead whale on the beach, you increase the probability that there will be shark and human interaction."

Perhaps that is why the great white shark baby was visiting Vineyard Sound.