Overview
- Monitoring data from early June show dissolved-oxygen at the Seemannshöft station fell under 2 mg/l and readings at Blankenese were briefly below 2 mg/l, according to the Bündnis Lebendige Tideelbe and the Hamburger Wassergütenetz.
- Conservation groups warn that oxygen below 4 mg/l causes severe stress for fish, values under about 3 mg/l can trigger fish kills, and levels near 2 mg/l are acutely lethal for many species and life stages.
- The Anglerverband Hamburg has reported dead animals, including two sturgeon, numerous endangered silver eels, and isolated bream, indicating that adults as well as juveniles are being affected.
- BUND, NABU and WWF blame the recurring oxygen deficits mainly on the Elbvertiefung deepening of the navigation channel and are calling for a rollback and rapid measures such as creating shallow-water refuge zones for fish.
- This episode continues a multi-year pattern of long low-oxygen periods—over 80 days under 4 mg/l in 2025 and more than 90 days in 2024—and experts warn warming temperatures and delayed mitigation raise the odds of lasting harm to river biodiversity and local fisheries.