Yale University finished last fiscal year in the black for the first time in 15 years, taking in an overall budget surplus of $52,000 for 1980-81, a Yale official said yesterday.

Gerald L. Stevens, vice president for finance and administration, attributed the surplus to sound management and to cut-backs in library spending, decreased numbers of junior faculty, and the demotion of sports such as volleyball and waterpolo from the varsity to the club status.

Stevens added that an unusual 28-percent rise in contributions gathered from annual fund raising helped balance the budget.

This increase, along with income from new investments, stimulated a 23-per-cent rise in the annual amount of money given to Yale's endowment, Stevens said. He added that although this rise in endowment did not affect the budget this year, "over time we'll be able to spend more money."

The quadrupling of oil prices in the early 1970s contributed to a $1.8 million deficit in the 1979-80 fiscal year, as well as deficits in other years, George F. Williams, Yale's manager of income budgeting, said this week. But conservation measures have helped alleviate these costs, he added.