Talisman Energy Inc. said Monday that its president and chief executive agreed to step down, effective immediately.

The Canadian oil and gas company did not give a reason for the departure of John Manzoni, who joined the company in 2007. It named Hal Kvisle, a director on its board and a former president and CEO of TransCanada Corp., to replace him.

Kvisle has more than 35 years of experience in oil and gas, midstream and pipeline operations, Talisman said.

Last month, the oil and gas company reported a decline in second-quarter net income, but still beat analysts’ forecasts for revenue. It blamed the lower results on falling oil and gas prices, with higher operating expenses and declining asset values.

Total production rose 4 percent on higher oil and gas volumes in Southeast Asia and from North American shale. But falling prices more than offset that growth. Benchmark crude prices dropped about 9 percent in the spring quarter, and natural gas prices were down by 48 percent.

U.S. shares of Calgary, Alberta-based Talisman rose 39 cents, or 2.7 percent, to $14.61 in late morning trading.