Canadian crude oil exports by rail for the three months ending in March declined by more than 25 percent year-on-year, federal data show.

The National Energy Board updated data on total crude oil exports by rail, showing an average 119,755 barrels per day were shipped for the three months ending in March. That's down 24 percent from the three-month period ending in December and 27 percent less than the same period in 2014.

Though rail shipments have declined recently, the volume delivered through March 2015 is six times greater than the volume delivered for the three months ending March 2012, data show.

North American crude oil production has increased to the point that it's more than the existing pipeline infrastructure can handle, leaving energy companies to rely more on rail for transport. More rail disasters involving crude oil have occurred in recent years as a result.

In March, the Transportation Safety Board of Canada dispatched investigators to the site of a derailment of a train carrying crude oil through the village of Gogama in Ontario, the second such derailment in the region in less than a month.

Canadian Transport Minister Lisa Raitt announced new regulations in April aimed at increasing safety on the Canadian rail system. The measure from regulator Transport Canada started with an order to remove around 5,000 tanker cars designated DOT-111 from service almost immediately.

Those types of cars were involved in the Lac-Megantic disaster in 2013, which left 47 people dead.