  We study a novel phase of active polar fluids, which is characterized by the
continuous creation and destruction of dense clusters due to self-sustained
turbulence. This state arises due to the interplay of the self-advection of the
aligned swimmers and their defect topology. The typical cluster size is
determined by the characteristic vortex size. Our results are obtained by
investigating a continuum model of compressible polar active fluids, which
incorporates typical experimental observations in bacterial suspensions by
assuming a non-monotone dependence of speed on density.
