Whales and dolphins may have returned to Bermuda's waters in large numbers for the first time this century.

Population growth and an increased food supply is believed to be the reason for reports of several humpback whales and a large school of dolphins which appear to have taken up part-time residence.

One of the World's leading cetacean authorities, Dr. Peter Stevick said: "There are historic records about the humpbacks living off Bermuda, and we'd expected that it could happen again.'' Dr. Stevick is Director of the North American Humpback Whale catalogue in Bar Harbour, Maine. He said: "With an increased population of humpbacks, it is likely that females with young calves and some of the less competitive males may have not migrated south for winter from the North Atlantic to the major humpback mating sites, off the Dominican Republic.

"It is very exciting to hear that they have been seen during this time around Bermuda. It there is plenty of food, they would have further cause to stay.'' The groups of humpbacks and dolphins were sighted by local diver Mr. Teddy Tucker and crew members, Mr. Nick Hutchings and Mr. Jonathan Saul, aboard the 63-foot Miss Wendy in December, February and last month.

Mr. Tucker, who has worked with the Bar Harbour scientists for many years while humpback tracking sessions were conducted off Bermuda, said: "In December and February, we have seen what we believe are the same four humpbacks.'' But 67-year-old Mr. Tucker said he believed the sighting of dolphins was even more exciting.

He said: "Three times we have seen about 200 of what I believe are Atlantic bottlenose variety. Never in my lifetime have I seen so many in one place off Bermuda. I believe that they were the same group at each sighting.'' He described the members of the group as slate-blue on the top and lighter on their bellies, and averaging seven to eight feet in length.

Mr. Tucker said the dolphins were swimming around his boat some five miles off the South Shore in approximately 400 fathoms.

He said: "They weren't going anywhere. They hung around the boat for as long as we were there. They were very active and very curious, and when I stopped the engines, they came around and hung around, jumping and puffing and squeaking.

"Everywhere you looked they were jumping, blowing and splashing. It was really exciting, really something to see.'' The highlight of one encounter for Mr. Hutchings and Mr. Saul was swimming with the dolphins.

Mr. Hutchings said: "It was a fantastic experience. I went in with my flippers and mask on, and swam `normally' with them for about a half hour, and they stayed about 20 to 30 feet away.

"Then I tried swimming like a dolphin with my feet together, moving up and down. They were really curious and came within five or six feet of me. That was scary because they swam at me really quickly and I wondered if they were going to stop.'' Mr. Tucker said: "They made no hostile moves toward either of them. They were just inquisitive.'' He noted that the high-energy dolphins need a food supply and speculated the group he encountered may have found that in abundance several miles off the Island.

On hearing of the dolphin sightings, Dr. Stevick said: "They could be Atlantic bottlenose or spotted dolphins. They are very opportunistic when it comes to food and if they found a reasonable supply of fish they could very well be living there.

"They like small schooling fish off the edge, and if the fish are too big or too hard to catch, they would not hang around. Also they could be moving with transitory schools of fish.'' He stressed that not much is known about the offshore dolphins because it is difficult to track them.

Whales were believed to be common off Bermuda up until the end of the last century, when hunting ships became more efficient.