Victoria, British Columbia: -- Canadian scientists say they are puzzled why dolphins, which normally stay in offshore waters, are showing up close to shore and in inlets on Vancouver Island.

Dolphins started moving closer to land in the mid-1980s but the reason is still unknown, researchers said. It could have been a result of a food shortage or changing water temperatures.

"They just keep increasing," Echo Bay, British Columbia, resident Billy Proctor told the Vancouver Sun. "I guess their population is probably exploding because there's tons of babies everywhere. I don't think they're supposed to be here."

Proctor said he sees hundreds of them daily hanging out close to shore.

Lance Barrett-Lennard, a zoologist with the Vancouver Aquarium, said he sees few dolphins in offshore waters, and that 15 years ago they were plentiful.

"I was a bit worried when I first went up where I usually see dolphins and there weren't any," he said. "For some reason they seem to be further inshore."

A recent rash of attacks on dolphins by transient killer whales may have also been a factor, Barrett-Lennard said.

Dolphins often play with resident killer whales, but when they see a transient killer whale they'll go the other way, said John Ford of Canada's Department of Fisheries and Oceans.