Canadian natural gas exports to the United States for the seven years ending in 2014 are down significantly because of U.S. shale production, a regulator said.

The National Energy Board said in a market snapshot natural gas exports are down dramatically. For the eastern United States, exports are down more than 65 percent for the seven years ending 2014. For the market in the U.S. Midwest, natural gas exports are down nearly 23 percent through 2014.

"Rapid development of unconventional gas projects has increased U.S. natural gas production," the NEB said. "As a result, natural gas exports from Canada to the U.S. have been decreasing."

NEB said pipeline revisions have shifted exports away from Midwest markets as well.

Canada relies heavily on export revenue from oil and natural gas. Statistics Canada reported last month real gross domestic product slipped 0.2 percent in May, the last full month for which data are available, for the fifth straight month for declines and a sign the Canadian economy is moving into formal recession.

"The decline in May was mostly a result of contractions in manufacturing, mining, quarrying, and oil and gas extraction as well as wholesale trade," the office reported.

The natural gas export situation for Canada could shift, however. A report from the U.S. Energy Information Administration finds production from seven shale basins in the United States reached 45.6 billion cubic feet per day in May for an all-time high. That's expected to drop 1.5 percent by September.

Of the seven basins reviewed in the latest drilling productivity report, EIA finds only the Utica shale basin in Ohio is expected to post an increase in short-term production.