A ship-to-ship transfer of Iranian crude oil between two dark tankers has resulted in a substantial oil spill in the Persian Gulf in the waters adjacent to Kuwait, Iraq, and Iran.

The transfer took place between the two Aframax tankers Fortune Galaxy (9257010) and Serano II (9165542) on September 29 and 30. A five kilometer-long oil slick is easily visible on satellite imagery.

The incident was first reported by industry site TankerTrackers, which categorized it as a large spill totalling around 5,400 barrels. “These spills happen regularly and go unreported,” the company said in a post.

With more than 2,000 ship-to-ship transfers by shadow fleet vessels around the world every year spills are a routine occurrence, say industry insiders. In 2023 nearly 400 millions barrels of sanctioned Iranian, Russian, and Venezuelan oil was transferred between ships.

Officially there have only been three major and 55 smaller oil spills across the global oceans in the last 25 years, though the actual figure is almost certainly much higher.

Shadow fleet operations generally rely on aging and often underinsured tankers, as was the case in Fortune Galaxy and Serano II with both vessels older than 25 years.

With the recent introduction of both oil and LNG shadow fleets operating in the Arctic, the environmental stakes have escalated further.

This summer has seen the transfer of more than 10 million barrels of sanctioned Russian crude oil via the icy Arctic waters of the Northern Sea Route. While some vessels possess light ice-class protection, others do not.

And lower ice-classes do not offer substantial protection, especially against layers of multi-year ice.

“Yet another huge ice class 1C crude oil tanker on the Northern Sea Route. Even with a low ice-class it still makes me uncomfortable,” one Arctic shipping expert told gCaptain.

This year thick sea ice persisted around Wrangel Island requiring continuous work by nuclear icebreakers to keep shipping lanes open.

Other vessels had to take substantial detours to avoid running into any sea ice.

“Ship had to perform an evasive maneuver just north-east of Wrangel Island to avoid troublesome ice. Unescorted, and with officers inexperienced in the hashtag Arctic, presumably, it seems reckless to allow such ships on the NSR, endangering the crew and with an environmental “Titanic risk,” says Kjell Eikland, founder of shipping data provider Eikland Energy.