Similar to the traffic heard on 6928.5 kHz USB at the same time, only slightly weaker signals. Information two-way communications, but much less "chatty" than the guys on 6928.5 kHz USB or the usual nighttime/evening time "pescadores" traffic often heard on various frequencies in the 6800-7000 kHz range (and others).
I'm considering the fact that these operations may be related to drug smugglers or are simply other radio hobbyists operating out of band.
That, or its fishing fleets that discovered their radios have a "mode" button