Escalating fuel prices and fears of gas shortage have cut tourism in the National Park System. Officials in western states report national park attendance is down from one year ago, although gas is readily available, but sometimes limited, at park sites.

The drop is most pronounced in Arizona where crowds at the state's prime tourist attraction - the Grand Canyon - fell 48 percent between May 1978 and May 1979.For the year as a whole, tourism is down 39 percent at the canyon.

"I'd say a lot of it has to do with the price of gasoline, or its availability, depending on where you are from," said park spokesman Roger Giddings. "Here in the park, there's no real problem. Gas purchases are limited to $10, and that will surely get you to the next town. Outside the park, just four miles away, you can get all the gas you want."

"The figures indicate people are staying closer to home this year because of the gas shortage," said Ed Winge, a Park Service spokesman in San Francisco. Winge said the number of visitors at 36 national parks in California, Hawaii, Nevada and Arizona has fallen about 7 percent through May.

One park - the Golden Gate National Recreational Area in San Francisco - has shown a dramatic 59 percent increase in usage.Winge said the increased figure is an indication that more people are using parks closer to urban areas and shying away from more remote locations.

"Parks located closer to urban areas are showing increases," he said.

Visitor traffic at Yosemite in California is down 8 percent from a year ago. At Redwood National Park near the California-Oregon border, the drop is 11 percent.

Some parks officials report a dramatic decline in automobile traffic and a corresponding increase in bus and plane usage. The number of passengers taking buses to the Grand Canyon increased more than 50 percent for May, and air travel was up 24 percent. Auto travel, meanwhile, declined 59 percent.

Park service officials in Colorade see a decline in visitors in parks there and in Utah, Wyoming, Montana, North Dakota and South Dakota. Requests for infomraion and reservations are down noticeably from a year ago, and officials say there is concern about fuel availability has increased.

Figures released in April show attendance at Zion National Park in Utah is down 30,000 from a year ago. At Yellowstone National Park, 108,000 visitors passed through the gates through April 1979 compared with 130,000 last year.

Officials in states such as Arizona - where tourism is the third largest industry, contributing $1.68 billion in revenue last year - are keeping a wary eye on the national park figures.

Paul Schafer, a spokesman for the state office of tourism, said incomplete calculations show tourism increased about 8 percent in the state during the first quarter of 1979 compared with the same period in 1978. He attributed the growth to increased airline travel and lower air discount fares.