Great photo, interesting comment by Tonga re exemptions.
Cannot comment for Bluff but in Westport tugs and barges require compulsory pilotage. The Master might have an exemption but they still require a pilot. That barge can lift approx 6000 tonnes.
Colours of both have changed in recent weeks, barge (at Newcastle NSW) is now red in place of the yellow, KATEA (at Gladstone Qld) now sports all blue funnels and deck-housing, with both branded with PB Sea-Tow logos.