A leading scientist following the BP oil spill said Monday that if the company or the government had made realistic estimates about the amounts flowing into the Gulf of Mexico, they could have had sufficient tanker space ready on the surface to hold the crude being pumped up through a make-shift collection device.

Instead, BP officials have acknowledged they may be constrained from pumping oil up too quickly because the surface ships there now can only receive only 15,000 barrels daily.

“They’re groping in the dark because they’ve never permitted actual estimates to be made,” said Ian MacDonald, a Florida State oceanography professor. “They said a dozen times on television that 5,000 barrels a day was the rate of this spill, and all their engineering was driven by that. Clearly, they were underestimating what kind of capacity they needed.”