The frequency is 11 departures per week (2 each weekday plus 1 Sunday service) which means there were 48 departures in the whole of April, including the return leg as well doubles that to 96.
1297 / 96 = 13.5 pax per flight (obviously that's not half a passenger, just an unrounded figure).
The Dornier 328 carries 32 pax so the LF is only just over 42%. Not great but that doesn't tell us what the yields are like, plus it's still relatively early days.