Rio Tinto was in the driver's seat of the capesize spot market as the mining giant continued to grab tonnage while freight rates declined.

The Australian miner fixed seven capesize bulkers since Wednesday to ship nearly 1.2m tonnes to Asia, according to the Baltic Exchange's fixture reports.

"In the Pacific, it was a Rio Tinto affair with the major charterer seeming to achieve better than last done with every fixture," the exchange said in its daily report.

Rio Tinto has agreed to pay $12.65 per tonne and $12.90 per tonne to hire two unnamed capesizes to send 170,000 tonnes of ore in each ship from Western Australia to China, loading to begin on 30 December.

In the Atlantic, it also hired a third unnamed capesize on Tuesday to transport the same amount of iron ore from Quebec to Japan, a longer and more expensive route, at $35 per tonne.

Loading will take place from 2 to 8 January.

On Monday, Rio Tinto signed a deal for a to-be-nominated capesize to ship another 170,000 tonnes of the steel ingredient from Western Australia to China at $13.60 per tonne.

Last Thursday, Rio Tinto hired two other capesizes to send 170,000 tonnes of ore each along that same route at slightly higher rates of $14.10 and $14.25 per tonne, with loading taking place from 25 to 27 December, according to Baltic Exchange data.

A day before that the miner booked Berge Bulk's 210,000-dwt Berge Bobotov (built 2021) to ship ore on the same leg at $14.95 per tonne. Loading will take place from 23 to 25 December.

The Baltic Exchange's average freight rate for capesizes to ship the mineral on that route slipped $0.96 per tonne on Tuesday to come in at $12.60 per tonne, which was down from $14.15 a week earlier.

In October, Rio Tinto lowered its 2021 iron ore production guidance to between 320m and 325m tonnes, down from between 325m and 340m tonnes, amid a tight labour market, Reuters has reported.

But Braemar ACM Shipbroking noted that the country's iron ore majors are still on track to ship about 80.4m tonnes of iron ore this month, up 4% from a year ago and up 14% from November.

"On the other hand, however, Australian volumes have performed extremely well so far this month," the London broking house said in a note on Tuesday.