The Economics Department has lost seven tenured professors in the last year. Meanwhile, by next fall, it will have tenured or regained six professors. Here are their stories:

*Abram Bergson, Professor of Economics, turns 70 years old this spring, reaching what he calls "the pleasant age of retirement." He expects successors to be found in his fields of expertise, which include comparative systems and socialist economics.

*Professor of Economics Martin S. Feldstein '61 is expected back at Harvard next fall. The current chairman of President Reagan's Council of Economic Advisors has taken two years of leave, the maximum for professor below the age of 66.

*Stanford Professor David M. Kreps came to Harvard last fall, touted as one of the hottest young economics theorists in the country. He returned to his old school in January after marrying as assistant professor it the Stanford School of Business Administration.

*Two faculty members died last year: John V. Lintner. Gund Professor of Economics and Business Administration, in June and Professor of Middle Eastern Studies A.J. Meyer in December.

*Dean of the Faculty Henry Rosovsky will return full-time to the Economics Department in July. But with his recently granted University Professorship and several years of accumulated leaves of absence, it is unclear how much Economics Rosovsky will be teaching in the immediate fututre.

*Professor of Economics Jeffrey D. Sachs, Lawrence H. Summers and Jeffrey C. Williamson--along with Kreps--were Harvard's new blood last fall. Sachs, promoted from Harvard's own junior faculty, specializes in international trade, Summer's forte is public finance and Williamson is an expert in economic history.

*Chariman of the Ec Department A. Michael Spence becomes dean of the Faculty in July, and he is not planning to teach any courses in the near future.

*Princeton Professor John Taylor accepted Harvard's tenure offer last May, but he subsequently picked Stanford.