Here's a report I found from a couple of days before Christmas:

Report: Spent a windy day fishing with local guide Wayne Hinrichs. He put us on fish after struggling for a few hours due the strong north wind, high pressure and near full moon. We finally found the fish in 35-40' of water on breaklines and fishing slow. Some fish caught on jigs and dartheads but most on dropshot with craw colored Roboworms and shad Power worms. Key was fishing slow. Combination of 30-35 smallies, spots and blacks caught - most in the 1.25-1.75 lb range. All in all, a great day on the water with a great friend and guide.

Tips: Slow and deep - smaller fish caught were in the 15-20' range. Better fish wer 35-40' range - find the breaklines. Fish were hugging the bottom as we graphed very few fish (or bait) that we caught.

You might also want to try asking your question on the Floattube/Kickboat board. Although I haven't seen anyone mention Berryessa there in a while.