Oslo-based rate benchmarking company Xeneta's XSI index has shown its biggest ever monthly rise in May.
The jump in long-term contracted rates shows the effect of 2018 deals expiring and new contracts lifting levels, it said.
According to the crowd-sourced index, which started in 2017, global rates leapt by 11.5% across the month, with US rates for imports climbing by 18.8%.
The increase follows on from a dire April for contracted liner business, with the indices at that point slumping by 4.2% after two months of increases.
Xeneta CEO Patrik Berglund said the changes were indicative of an increasingly "topsy turvy" rate landscape.
"We’d already started seeing contracts populating the platform at higher levels than last year at that point, particularly for the transpacific, and that has helped propel this increase," he added
Berglund said the the tit-for-tat tariff battle between the US and China is the biggest factor.
He added: “Front loading due to the tariff scare raised short-term rates making it a favourable seller market, but now rates have started dropping again. As those rates dropped, BCOs and carriers settled long-term contracted rates on the back of an artificially healthy short-term market."
Patience pays off for shippers
“The clear winners for the transpacific contract season are the shippers who have held off concluding their negotiations, as well as carriers, who on the flip side grasped on to early contract conclusions," Berglund said.
"Unfortunately, buyers who settled contracts early on, or mid transpacific contract season, will not reap the benefits as the dust settles from the short-term market. ”
But the company warned increased costs related to the tariffs may have a longer-term impact on demand.
Consultancy Drewry said this week that lines are debating whether to cut back on transpacific capacity following an escalation in the tariff war.
It added owner will be wary of how average ship utilisation fell during the first quarter and the impact it had on spot rates that dropped to their lowest point since June 2018 in March, it added.
"The mini-recovery in rates in April that has mostly held during May indicates that ships are fuller now, but we expect that carriers will be considering some capacity retrenchment to counter potential lost traffic as a result of the trade war," it said.
