More than 80 percent of venture capitalists believe the initial public offering market is at very weak levels, according to a new survey from Deloitte and the National Venture Capital Association.

The relative dearth of public offerings curbs returns to venture capital investors, crimping the VC industry, they say.

The IPO market has been picking up of late, but remains weak by historic standards. In the U.S., 75 IPOS have priced this year, up 27 percent from this time last year, according to Connecticut-based Renaissance Capital. Proceeds in the first quarter totaled $13.3 billion, more than double last year.

Traditionally, more venture-capital investments find exits through acquisitions than through IPOs, but public markets remain a key part of overall venture-capital strategy.

Some investors worry that the performance of online radio company Pandora Media's

IPO could put a crimp on the market. Pandora debuted on the New York Stock Exchange last week and the stock has fallen below its offer price of $16 after a short, sharp rise.

The venture investors also said they were beefing up investments in cloud computing, social and new media, and clean technology.

The survey consulted venture capitalists globally, including in the United States, China and the U.K.

(Reporting by Sarah McBride, editing by Bernard Orr)

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