Unemployment among people with doctorates is very low, about 3.5%, according to the Bureau of Labor Statistics, and even lower among scientific disciplines. Many of those highly educated individuals trained to do lab research find that career blocked, [Boston College biology professor David] Burgess says, even though they are conducting research that would have received funding in past decades.The bolded (by me) statement above does not make sense. BLS-measured unemployment for Ph.D.s of all disciplines in 2012 was 2.5%. I don't believe there are numbers for 2013 yet. If Mr. Vergano's numbers are for 2013, then Ph.D. unemployment has actually increased. (It's possible that he asked BLS for the latest numbers.)
In addition, I don't believe that any governmental or private organization has accurate measurements of unemployment among scientists (especially ones that can be compared to BLS numbers.) Sure, you can use the NSF Survey of Earned Doctorates, but that only tells you about young scientists (i.e. ones that have just graduated.) NSF's data from the Survey of Doctoral Recipients might be used for these numbers, but I don't think you can compare them to BLS numbers and the latest data is from 2010.
A mystery -- I'll look into it.