Executives from reinsurers including Swiss Re and Allianz Re say prices for catastrophe coverage should rise next year after disasters from New Zealand to Japan drove up claims and low interest rates hurt investment returns.

"The fat is gone and now you really need to make your money as an underwriter," said Brian Gray, the chief underwriting officer at Swiss Re, at a roundtable of reinsurance executives hosted by Bloomberg News in Zurich. "The biggest challenge for the industry is the interest-rate shock, and that has not got the same kind of attention as natural catastrophes."

The earthquake and tsunami that struck Japan in March were among events that caused record insured losses of $70 billion in the first half of the year, according to Guy Carpenter & Co., the reinsurance brokerage of Marsh & McLennan Cos. At the same time, low interest rates are crimping investment returns, which typically provide a buffer for earnings when claims rise. Yields on benchmark 10-year German government bonds fell below 2 percent yesterday for the first time.