Cape Town - Beaches in Knysna and Cape Town, that were closed following shark sightings earlier this week, have reopened after getting the all-clear.In Knysna, municipal authorities closed the area between Maoli Beach, Sedgefield and Brenton-on-Sea because of the high number of sharks spotted since Tuesday, according to the National Sea Rescue Institute's (NSRI) Knysna station commander Jerome Simonis.Close to midday on Wednesday, authorities announced on Twitter that the popular beaches had reopened.Swimmers and paddlers were encourged to stay alert.#GreaterKnysna #beaches REOPENED. No #GreatWhite #Sharks spotted near beaches today Remain vigilant @DA_Eleanore @KnysnaPlett @knysnatourism pic.twitter.com/Xbbga9TXFf— KnysnaMunicipality (@KnysnaMuni) December 28, 2016Further along the coast in Cape Town, Shark Spotters' research manager Alison Kock said beaches there had also reopened after sightings at Clovelly and Fish Hoek beaches.The sightings indicated that it could either have been a great white or bronze belly shark, because some of their features overlap.Kock explained that the sharks were currently trawling for food in the warmer summer waters, and were following the schools of fish to nibble on."Shark sightings are quite common in Cape Town for this time of year," said Kock."The sharks are, we believe, following schools of fish, like game fish, bait fish and yellow tail close to the shore at this time of year. They also include smaller sharks in their diet," she said.The Shark Spotters have devised a flag system to warn bathers when it is not safe to enter the water.- Green Flag: Spotting conditions are good- Black Flag: Spotting conditions are poor- Red Flad: High shark alert- White Flag: Shark has been spotted.