Two gates, two stories
Bosphorus (-12%): the gate for legal exports — Ukrainian, Romanian and Kazakh grain in transit. Some of that decline is just the war. The rest is cargo finding other ways out, onto the Danube and through Constanța.
Kerch (+52%): the gate to the Sea of Azov, carrying Russian grain and steel. The half-again rise since 2023 is consistent with rerouting of Russian logistics through Azov — though consistent isn't the same as proven, and the transit signal only tells us vessels moved, not what they carried or where it was headed.
A caveat that matters more here than anywhere else in this briefing: a sanctioned corridor is exactly where AIS tends to lie. Industry tracking put the active sanctions-evasion "dark fleet" above 1,900 tankers in 2025, and AIS identity spoofing — broadcasting another vessel's identity, or falsifying position — is a documented tactic for this kind of traffic. So the +52% figure is probably a floor on real Kerch traffic, not a ceiling. Vessels running dark simply wouldn't show up in this count. The tactic itself is well documented: C4ADS's 2019 "Above Us Only Stars" investigation logged 9,883 suspected GNSS-spoofing incidents affecting 1,311 civilian vessels since 2016, concentrated around the Black Sea and Russian coastal facilities — the same waters this briefing watches. And the fleet doing it keeps growing: S&P Global counted 978 sanctioned-oil tankers in the shadow fleet by September 2025, roughly 18.5% of the world's oil-tanker capacity, up sharply from a year earlier.
None of that traffic has to hide from radar the way it hides from AIS. Synthetic-aperture radar satellites such as Sentinel-1 image the sea surface regardless of cloud cover or darkness and flag any hull-sized reflector on the water; cross-referencing those detections against AIS broadcasts is the standard method for finding vessels that are physically present but not transmitting — a technique already used to map "dark shipping" zones in other contested waters. It is a different sensing layer from the transit counts above, but the same logic: read the strait itself, not just what it reports about itself.
We watch the fields too. Where the war cuts off statistics, satellites keep measuring plantings, and our pipeline tracks oblast-level yields across Ukraine back to 1990, combining national statistics with satellite-derived estimates. For scale, the Ukraine-led corridor that replaced the UN-brokered Black Sea Grain Initiative moved roughly 120 million tonnes of cargo to 53 countries between September 2023 and mid-May 2024, per World Bank and USDA reporting — the volume the gate-level transit counts above are tracking week by week.