The scores of dead fish and birds found at Rosendal Dam recently weren’t killed by pollution or any other sinister cause, the City of Cape Town has confirmed.
Instead, the fish’s death is due to a lack of fresh water in the summer months, while the birds could have died because of a number of reasons.
Residents started noticing dead birds at the dam earlier in January. Soon, dead fish popped up ashore as though they fell from the sky.
Eversdal resident Armand Fritz who recently moved to the area says he walks to the dam regularly.
“I have noticed how polluted the dam is and how many geese have been dying of some sort of sickness. It is mostly the Egyptian Geese that are afflicted and they are dying at a rate of one per week.”
When he saw how a gosling was struggling, it was the last straw and he contacted as many authorities as he could.
“It has been heartbreaking watching their numbers slowly decline.”
Patricia van der Ross, Mayco member for community services and health, says recreation and parks staff visited the dam numerous times after the first reports came through. On 21 January they found three birds and 18 carcasses and on 24 January a further 13 fish carcasses were found. The carcasses were buried on site. Last Thursday no dead animals were found and Van der Ross says they will inspect the area throughout the summer.
She says the birds possibly died from avian botulism, a paralytic disease caused by bacteria, but it usually leads to the death of more birds.
“All three bird carcases had bite marks, but staff were unable to determine whether the animals were hunted or the dead animals were eaten at.”
When people feed birds this causes an “unbalanced increase in their populations”, and this raises the risk of avian botulism, she warns.
When they find more birds dying more frequently at the same dam during the summer months, the City will collect and send carcasses for testing, which wasn’t deemed necessary.
The 31 fish were killed by a lack of fresh water.
“No fresh water runs or seeps into this man-made dam during dry summer months. As a result, water quality deteriorates by the middle of summer as pollutants become concentrated and oxygen levels decline. Draining the dam every summer, to replicate a seasonal water body, will prevent the reoccurrence of fish dying and reduce the environmental health hazards and the nuisance of foul smells, and scattered carcasses which are an eyesore.”
The dead fish were also all part of a declared invasive species.
The fact that the birds and fish died at the same time seems to be unrelated, yet the extreme heat experienced earlier in January undoubtedly helped the process.
