03/01/2026
𝗨𝗽𝗱𝗮𝘁𝗲 𝗼𝗻 𝗳𝗶𝘀𝗵 𝗸𝗶𝗹𝗹𝘀: 𝗘𝗺𝗲𝗿𝗴𝗲𝗻𝗰𝘆 𝗺𝗲𝗰𝗵𝗮𝗻𝗶𝗰𝗮𝗹 𝗯𝗿𝗲𝗮𝗰𝗵𝗶𝗻𝗴 𝗰𝗼𝗻𝗰𝗹𝘂𝗱𝗲𝗱 - Issued by Mossel Bay Municipality - 3 January 2026, 14:00
The emergency mechanical breaching of the Hartenbos Estuary early this morning, 3 January 2025 confirms the cause of fish mortality noticed.
Critically low dissolved oxygen levels were recorded in the system, triggering an intervention in accordance with the provisions of the Approved Estuary Mouth Management Plan, which allows for emergency breaching when ecological functioning is threatened.
A contractor was deployed onsite in the early hours of the morning. Clean-up operations are being conducted and continues following the fish mortality event.
Scientific observations have confirmed that the fish kill resulted from severe oxygen depletion within the estuary. The oxygen deficit was caused by an algal bloom, exacerbated by a combination of low water levels, elevated temperatures, and nutrient‑rich conditions - all factors known to accelerate oxygen consumption and create hypoxic conditions.
The Garden Route District Municipality, through its regular recreational water quality sampling programme, has verified that all recent water samples for the Hartenbos Estuary were compliant with applicable standards.
