Police said it was not clear at this stage what happened but the kayak was seen upturned on the water and the pair disappeared under the water and didn't resurface.
Locals and holidaymakers joined emergency service personnel and Coastguard in the search for the pair and an air search was also carried out by the BayTrust Rescue helicopter.
Local divers had also gone into the water to help search for the pair.
The kayak, a paddle and an adult life-jacket were recovered earlier.
It was understood the child was wearing the adult life-jacket and the father was not believed to have been wearing one.
Reporter at the scene Mike Watson said earlier today emergency services were searching an area about 50m from the shore. He said lake conditions were calm.