(Bloomberg) — Shipments of crude to the U.S. from Mexico fell to a new low last week, extending a trend that goes back to when the Energy Information Administration (EIA) began compiling preliminary weekly import data in June 2010.

Imports totaled 290,000 bbls a day in the week ended April 14, a 43 per cent weekly drop that may have been triggered by weather-related closings at Mexico’s key export ports this month. But the shipments have been sinking for years. The 52-week average through April 14 was 561,000 bbls a day, down from about 630,000 a year earlier.

“The latest import levels are continuing a long trend,” Court Smith, director of research with shipbrokers MJLF & Associates, said by instant message from Stamford, Connecticut. “This is because of a combination of recent rise in refinery rates and historically declining production in Mexico.”

Production in Mexico has declined for 12 years in a row and this year will be less than two million bbls a day, the lowest level since 1980, according to Petroleos Mexicanos, the state producer, hurting sales of the benchmark Maya heavy crude.

Pemex’s six refineries are also using more of the crude, lessening the need for exports. They processed 930,400 bbls a day in February, the most since June of last year, according to Mexico’s Energy Information Agency. The company expects to raise rates further to boost gasoline supply in the near term.

Refiners on the U.S. Gulf Coast, which are the primary users of Mexican crude, have been turning north for supplies, said Andy Lipow, president of Lipow Oil Associates, a Houston-based consulting company. Canadian imports averaged 3.16 million bbls a day over the 52 weeks through April 14, up from about 3.02 million a year earlier.

“Canadian crudes are making more headway into the U.S judging from the full pipes coming down from Canada,” Lipow said by phone Friday. “We do expect to see more heavy crude from Canada when projects like Suncor Energy Inc.’s Fort Hills mine comes online toward end of the year.”

Europe, Asia

Mexico has increasingly turned to Europe and Asia to make up for the U.S. demand shortfall. While overall Mexican crude exports fell in the first half of April, sales to Spain have increased since February, according to estimates from vessel-tracking and U.S. bills of lading data compiled by Bloomberg oil-market specialist Bert Gilbert. Exports to India, South Korea, Japan and China also grew in February, Mexico customs data compiled by Bloomberg show.

“While U.S. Gulf refineries were in maintenance, heavy crude oil producers have had to send their shipments to other regions, such as Asia, where heavy crude has recently strengthened thanks to the OPEC cut,” said Ixchel Castro, an analyst at Wood Mackenzie in Mexico City. “Greater shipments of Maya to Asia allows Pemex to achieve better margins for its exports.”

Mexico crude imports may pick up as gasoline demand rises for summer and refinery maintenance ends, Castro said in an emailed response to questions.

“This is the season where we would normally expect more heavy crude imports for U.S. Gulf Coast coking plants,” she said.

Pemex didn’t respond to requests for comment.