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29 June 2015

Progress of fish kills in Swartvlei

It is still predominantly Grunter that is being collected although we did also collect 2 Mullet and 1 Black Finned Eel.

The mortality has been very localised and limited to mostly the area south of the picnic area at Placid Waters and north of the slipway off Kingfisher Drive. The mullet were found off the Island and 1 Grunter was found close to Pine Lake Marina.

Detailed sampling included the following with findings:

  • Prawns being the predominate diet of Grunter were collected and prawn beds sampled. The prawns appeared healthy and there were no visible signs suggesting that there were any problems, prawns with eggs were noticed suggesting that things appeared normal. Samples of prawn were preserved with the purpose of sending away for testing.
  • We expect the results of the water tests (chemical and micro) early next week and will communicate these results.
  • As noted in earlier feedback the, temperature, conductivity, pH, oxygen % and oxygen mg/l readings taken are all within normal parameters. If there are serious problems with these parameters we could expect to see numerous species being impacted, not only predominantly Grunter.
  • The tissue samples were sent away to a laboratory in Pretoria and the analysis can take up to six weeks. Kyle Smith, SANParks Marine Scientist, conducted an autopsy of fish but could not find any visible signs of parasites.

Acting Area Manager, Carel van der Merwe has thanked the Wilderness Field Rangers for collecting and handling dead rotting fish. He further thanked the Sedgefield community members and media for assisting to identify this problem. He also cautioned residents not to pick up dead fish, even if it does not smell rotten, and take it home for the braai.