Exports declined one percent while imports fell 2.2 percent, as a result of lower prices, the government agency said.
Both export and import volumes rose for a third consecutive month, albeit at a slower pace than in previous months.
The trade balance in March was revised downwards to a 236 million Canadian dollar (228 million US) deficit from a 254 million Canadian dollar (250 million US) surplus previously.
Exports of precious metals fell 27.4 percent in April, said Statistics Canada. Fertilizer exports declined 13.7 percent due to lower exports of potash. Exports of natural gas fell 20.9 percent, reflecting lower prices and volumes. Exports of animal products, namely mink fur, and nickel ores were up.
Imports of chemicals and plastics, meanwhile, declined 10.0 percent, mainly due to lower imports of organic chemicals, notably active pharmaceutical ingredients. After reaching record highs in March, precious metal imports fell 30.8 percent.
Trade with the United States remained mostly flat at 3.8 billion dollars (3.7 billion US).
Exports to the European Union, however, fell 23.4 percent while imports fell 7.0 percent, led by decreases in precious metals from the European Union.