Nova Scotia, one of Canada's Atlantic Provinces, which shares a kinship with Scotland, is preparing to play host this summer to 12,000 visitors of Scottish descent representing 34 clans from around the world.

On June 28 at Metro Center in Halifax, the capital, her majesty the Queen Mother will inaugurate the first International Gathering of the Clans to be held outside of Scotland. The festival, which will take place in cities, towns and villiages across the province, will run until Aug. 12. (For details, write to The Fathering, P.O. Box 130, Halifax, Nova Scotia, Canada B3J 2R5.)

Nova Scotia has many place names of Scottish origin and the Scottish heritage is obvious. It is almost an island, with 4,625 miles of coastline, so the visitor - as in Scotland - is never far from the sea. Nova Scotia is one of the Maritimes, which also include Newfoundland, Prince Edward Island and New Brunswick.

Since the friendly, picturesque Atlantic Provinces draw their major share of tourism from the northeastern United States, the Canadian Government Office of Tourism is "very concerned" about the possible effect that U.S. gas shortages might have on vacation auto travel to Canada this summer.

"If you have problems, we have problems" in any one of the border provinces, said Jack Van Dusen, manager of tourism information, in Ottawa. He pointed out, however, that once a motorist arrives in Canada, there is no gasoline problem.

One unusual non-energy threat that Canadian tourism may face this season concerns the campaign by Cleveland Amory, president of the Fund fro Animals, to bring about an end to the killing of baby harp seals for fur in New-foundland. A recent mass mailing by the fund asks Americans who support the organization's goal not to travel to Canada in hope that the government will abandon the seal industry in favor of the more lucrative tourism industry.

Travel Trade, a travel industry newspaper, said that Amory in a recent interview proposed helping Canada "open a new tourist industry based on the observation of the life and birth of baby seals." Van Dusen said he did not know of any contact between Amory and Canadian tourism officials.