Yes they do if you believe the theory developed by Stephen hawking back in 1975. In particular, the most emission today should come from the low-mass variety with masses of only 1 trillion grams or less. If these were produced in significant numbers soon after the Big Bang, they should just about now be undergoing their last burst of evaporation yielding gamma rays, X-rays and a hail of charged particles. So far, no X-ray flashes have ever been seen associated with gamma-ray bursts which would seem to argue against these bursts being evaporating mini-black holes. Also, it is possible to predict theoretically how the intensity of an evaporating black hole should appear over time, and there ought to be a long, bright initial outburst that preceded the burst. Such steady increases in luminosity have never been detected. Gamma ray bursts seem to be all or nothing affairs lasting seconds to minutes, not hours to weeks or more. And they do not produce broad-spectrum radiation as evaporating black holes might be expected to.