As many as 70 vessels are stuck waiting near the Danube River's Sulina Canal, as a shortage of pilots, disruptions from Russian attacks in the Black Sea, and limited canal capacity have slowed traffic toward Ukraine's river ports.

According to Reuters, Russian forces have blocked Ukraine's ports along the Black Sea, which typically handle 90% of the country's grain exports. That's forced shipments to reroute through ports along the Danube River, where capacity is tighter, and ships carrying grain have to compete with higher priority shipments of fuel.

Ukraine's agriculture ministry estimates that the country exported just 539,000 tons of grain between August 1 and August 21, down from 1.73 million tons over that same period last year. The bottleneck has only grown more severe in recent weeks, with ships arriving at the Sulina Canal faster than authorities can move them through.

Consultancy ASAP Agri warned in an August 25 alert that congestion along the Danube could worsen if weather conditions continue to deteriorate in the coming days, potentially extending wait times for ships already queued near the Sulina Canal. The Danube's shipping capacity has also already been strained by historic summer drought conditions, which have lowered water levels and forced vessels to carry less cargo in order to move through the river's chokepoints.