Workers connect drill bits and drill collars, used to extract natural petroleum, on Endeavor Energy Resources' Big Dog Drilling Rig 22 in the Permian basin outside of Midland, Texas.

Hiring is picking up in the oil fields, but a sell-off in the crude market last week has created fresh uncertainty for jobs in the industry. Employment data released last week suggest that improvement in the first three months of the year is continuing into the second quarter. Layoffs in the energy sector are at a nearly one-year low, but the industry was the biggest job cutter among U.S.-based companies in 2015 and 2016, so recruiters and hiring managers remain guarded. "We are sort of holding our breath to see if the first four months was a fluke," said Gladney Darroh, president of Houston-based energy recruiting firm Piper-Morgan. On Friday, monthly jobs data showed employment in the oil and gas extraction sector holding between 177,000 and 181,000 positions, continuing a trend that began a year ago. That suggests employment in the sector has at least stabilized after dropping from roughly 200,000 positions since October 2014.

The latest quarterly data from the U.S. Census Bureau's more comprehensive count of employers indicates a similar trend may be emerging in two related sectors: drilling oil and gas wells and support services for oil and gas operations. The stabilization is due in part to a decline in layoffs. U.S.-based energy companies announced plans to drop 459 workers in April, the lowest tally since June 2015, outplacement firm Challenger, Gray & Christmas reported Thursday. That makes April only the second month that employers handed out fewer than 1,000 pink slips since October 2014, a month before the Organization of the Petroleum Exporting Countries decided against cutting production.