Those 3 vleis are actually very interesting. Of the 3 vleis, only 1 runs off into the sea and is called GrootVlei or Grootwitvlei.
Of the 2 closed vleis - The small one closer to Pringle Bay side is called Rondevlei, and the smallest one closer to Kleinmond is called Malkopvlei - also known as Bass Lake! Now before you get too excited, it could be so named becasue it's situated on Bass Road.
These two smaller lakes have very different PH - one is quite alkaline and the other acid. Not hugely different but enought ot support very different flora and fauna. I read this in a little publication called Fynbos Coast, but would have to check on these details to be sure.
https://www.google.co.za/maps/@-34.3623615,18.8915315,15z
The below page suggest fishermen at Grootvlei.
http://www.getbirding.com/?p=1401
Hopefully this helps you find a few bass.