North Dakota’s Bakken Shale oil production under-performed in its most recent monthly statistics, reflecting a “serious shortage of hydraulic fracturing (fracking) crews,” the state’s chief oil/natural gas regulator Lynn Helms reported Tuesday.

Helms told a webinar with reporters that he expects to see improvement in the summer months, but the May statistics — 34.9 million bbls (1.127 million b/d) compared to 33.6 million bbls (1.123 million b/d in April) — come with eight fracking crews in the field compared to the usual 20-25 such crews at the current level of prices around $60/bbl.

“Operators are trying with all their resources to hire, but they are not finding employees who want to come back to the industry and come back to North Dakota, ” said Helms, director of...