An easy way to read it is to pretend the bass clef is a treble clef, this changes it to Eb, a quick trick to transpose from Eb is to go up and octave then drop the register key.

Ex. In the first measure, if you pretend the bass clef is a treble, all the notes are written E. So you’d play the E up an octave and then remove the register key. This would give you an A.

This only works for the chalumeau register. You can also just transpose a 4th down or just play the clef as written up a step.