At least one person on campus has done OK as the economy has declined: public university presidents’ salaries climbed 7.6 percent last year.

Fifteen presidents of public research universities took home at least $700,000 in 2007-08, up from eight in last year’s survey, and nearly one-third now earn over $500,000, according to the annual Chronicle of Higher Education survey out Monday.

The salary increases almost entirely reflect contracts signed before the economy turned sharply downward, and the boards that govern colleges argue that retaining top talent is even more critical during a crisis.

But the latest figures will likely attract more criticism this year because colleges and universities across the country are slashing budgets, with many laying off staff. Despite the troubled economy, public universities increased tuition 6.4 percent this fall, according to recent figures from College Board.

“The Chronicle’s study shows that the executive suite seems insulated from budget crunches,” said Sen. Charles Grassley, R.-Iowa, who has been the sharpest critic in Congress of pay practices at colleges and other nonprofits. “In these hard economic times, apparently belt-tightening is for families and students, not university presidents.”

The median salary for public university presidents – now $427,400 – is almost exactly $100,000 less than at private universities, where the median salary barely changed. But the gap is narrowing as public universities are increasingly willing to spend big money to keep their leaders from being lured away by private schools.

Governing boards, which increasingly comprise people from the business world, “see the investment in a CEO as the single most cost-effective investment they can make in the whole university,” said Raymond Cotton, a Washington attorney who specializes in college presidential compensation matters. But if the downturn continues, “I believe you will have a cooling effect” on compensation, he said.

Chronicle editor Jeffrey Selingo said there is less data covering previous national economic downturns, but that they did not appear to slow the upward trend of presidential salaries.

“The explanation could be in down times boards think you need to pay for stable leadership,” he said.

The highest-paid president in this year’s survey, reporting compensation of $2.8 million for 2006-07, is David Sargent, the longtime president of private Suffolk University in Boston. That’s the most recent year for which data is available for the Chronicle survey, so the private college figures lag a year behind.

Most of Sargent’s compensation came from various bonuses, however, including $1.19 million, which he will not receive until he retires, for sabbaticals that Sargent never took, plus a longevity bonus that equaled his $436,000 base salary.

Suffolk spokesman Greg Gatlin said Sargent, 77, has worked at Suffolk for 52 years and in 2005-06 earned less than the presidents of 75 percent of Suffolk’s peer universities, according to compensation experts the school consulted.

Sargent’s pay package “was designed with the understanding that President Sargent’s value to the university has been, and is extraordinary, that the past compensation was inadequate and not commensurate with his leadership,” Suffolk board chair Nicholas A. Macaronis said in a statement. He said Sargent “never took sabbatical or other entitlements usually given to executives at his level.”

Gordon Gee of Ohio State was the highest paid public university president, earning $1,346,000, including a recently announced $310,000 bonus. Michael McCall of the Kentucky Community and Technical College System was the highest-paid community college leader with total compensation valued at $610,670.

The Chronicle identified a number of presidents who have declined or returned bonuses because of the economic crisis, including Michael Hogan at the University of Connecticut, James Ramsey at the University of Louisville and Richard McCormick at Rutgers.