At first it seemed like somebody was tuning up on frequency, but then two-way traffic in SSB mode was noticed. Usually 6955 kHz USB is used by pirates but these are almost certainly fishing fleets using HF-SSB radios modified for open band transmit (freeband frequency modification, or MARS/CAP mod - the radios are likely re-purposed amateur equipment given the heavy use of LSB mode).
6955 kHz USB - 6.955 MHz USB Portuguese language chatter fishing fleets peskies on a commonly used pirate radio frequency