Though the student body will grow by roughly 800 students when Yale’s two new residential colleges are completed, the size of the faculty has remained stagnant since the onset of the nationwide economic recession in 2008.

The number of tenured and tenure-track professors in the Faculty of Arts and Sciences has hovered around 700 over the past four years but dropped to 682 this fall — down from 691 in 2011 and over 700 in 2010 — Deputy Provost Lloyd Suttle said in a Sunday email. While he said 70 searches in 39 departments and programs are in progress this fall and “about a dozen” searches are under consideration for approval, he noted that these searches aim primarily to fill existing positions rather than to create new ones.

With the faculty size stagnated, five department chairs interviewed said their departments struggle to cover new areas of research because they are unable to hire more professors.

Provost Peter Salovey said Yale has not increased the proportion of its budget devoted to faculty hiring, adding that the University will need to increase the faculty size in the future if it is to meet the demands of a larger student body. He said the ongoing comprehensive academic review of the Faculty of Arts and Sciences — last held at the University roughly two decades ago — will evaluate departmental organization and soon advise the University on the optimal future size of the faculty.

The size of the Faculty of Arts and Sciences has been held at roughly 700 since the financial downturn tore a $350 million hole in Yale’s budget. While University finances have begun to stabilize, Yale’s $19.3 billion endowment has yet to return to the dramatic growth of the mid-2000s, when it saw annual returns of around or above 20 percent. The endowment posted a 21.9 percent return on investments in fiscal year 2011, but its performance fell to 4.7 percent in the latest fiscal year.

The University’s “smoothing rule” keeps spending from the endowment relatively consistent on an annual basis despite fluctuations in investment performance. The annual returns of Yale’s endowment affect the University’s long-term financial plan, Suttle said, but administrators do not adjust the budget based on a single year’s performance.

Professors interviewed said the inability to create and fill new positions over the past few years has stunted their departments’ potential.

The Comparative Literature Department was hit particularly hard by the faculty hiring freeze, department chair Dudley Andrews said, as it had already fallen from roughly 17 to nine professors due to deaths and retirements before the budget crisis.

Many of these vacancies have gone unfilled since then, as the department has roughly 10 faculty members now.

The department is conducting three searches this year, two of which are joint searches with other departments.

“If we hire well this year, that would be a big boost,” he said. “It would help with making us feel like we’ve got our body mass back.”

Even as departments turn to joint appointments as a means of lessening the effects of limited hiring, department chairs said the current faculty size negatively affects their departments’ efforts to broaden their academic focus.

Edward Kamens, chair of the East Asian Languages and Literatures Department, said that if his department were given resources for expansion, it would like to add a position in Korean literature if such an appointment were part of a larger expansion of Korean studies at Yale.

Paul Turner, chair of the Department of Ecology and Evolutionary Biology, said the restrictions on faculty hiring preclude departments from exploring some new areas of academic inquiry.

“If you ask just about any department, there are as many classically important things to study as ever, and there’s always a growth of new areas,” Turner said. “The ambitions to have new fields represented in the department will occur faster than the disappearance of old fields.”

Yale’s endowment was valued at $19.3 billion as of June 30.

Correction: Oct. 24

A previous version of this article mistakenly suggested that Edward Kamens, chair of the East Asian Languages and Literatures Department, said it would be impossible to add a position in Korean literature as part of a larger expansion of Korean studies at Yale due to the limited resources currently available. In fact, he said that if his department were given resources for expansion, it would likely seek authorization to add a position in Korean literature if it were part of a larger expansion of Korean studies.