North coast beaches close after major fish kill. (Photo: Tessa Duane) 
Two beaches on the KwaZulu-Natal North Coast have been closed as a precaution after being littered with dead and dying fish over the past two days. The cause has not yet been established.
The biggest fish kill was at the mouth of the Umhlali River near Tinley Manor beach, where residents found hundreds of dead fish early on Thursday, 12 February. By Friday morning, more dead and dying fish were found in the tidal pool at Shaka’s Rock – about 8km south of the previous fish kill.
/file/attachments/orphans/tonyfishkill3imageTessaDuane_557800.jpg "Dead fish at Umhlali River. (Photo: Tessa Duane)")
Tessa Duane, a local resident and chair of the Dolphin Coast Conservancy, who visited the river estuary at around 10am on 12 February, said she was shocked by the scale of the deaths – affecting everything from crabs and shrimps to larger estuarine fish.
While no definitive answers have emerged so far, ecologists have suggested a wide variety of possible causes – ranging from sewage or chemical pollution to unusually high temperatures and low oxygen levels.
Closure of two beaches
The local KwaDukuza Municipality issued a statement on Friday, 13 February announcing the closure of the Umhlali River mouth and the Shaka’s Cove tidal pool, with immediate effect.
/file/attachments/orphans/fishkill4shakasrockimageKarlMrazek_348381.jpg "Residents try to save dying fish near Shaka's Cove tidal pool. (Photo: Karl Mrazek)")
The municipality also warned residents not to eat any dead fish, and to keep children and pets away from the affected areas. Bathers were cautioned not to swim there until the cause of the deaths was established.
Read more: From Blue Flag to brown water: Durban’s coastal dilemma amidst sewage management failures
“Relevant authorities are actively monitoring the situation and will provide updates as further information becomes available. The affected areas will only be reopened once it has been confirmed that conditions are safe for public use.”
Video clips show a wide variety of dead fish, including barracuda, kingfish, queenfish, mullet, grunter, stumpnose, ponyfish and tilapia.
/file/attachments/orphans/tonyfishkill6imagetessaduane_670877.jpg "A ponyfish is a victim. Many dead fish washed up at Mhlali River this week. (Photo: Tessa Duane)")
/file/attachments/orphans/tonyfishkill2imafeTessaDuane_459789.jpg "With two beaches closed, the cause of the fish kill remains unclear. (Photo: Tessa Duane)")
/file/attachments/orphans/tonyfishkill5imagetessaduane_395306.jpg "Dead baracuda fish at the Mhlali River mouth. (Photo: Tessa Duane)")
Ecologists contacted by Daily Maverick said they were hesitant to speculate about the cause of the deaths until the results of water samples and other information became available.
However, one of the estuarine experts noted that fish kills often occur shortly before dawn, when oxygen levels in the water are at their lowest due to a lack of photosynthesis during the night. The presence of high levels of sewage can also cause oxygen levels to plummet rapidly, while heavy rainfall can lead to the breaching of a river mouth, killing fish due to the sudden introduction of colder and more salty water from the sea.
Hundreds of dead fish were also discovered in the mouth of the Isipingo River, south of Durban, about 10 days ago, following a major sewage leak. DM
