public records of sellers to buyers of private vineyards

[vineyardvixen]

I own a small vineyard in sonoma and contract it out to someone who does all the maintence and picking, then he either keeps the crop or sells to larger vineyards. My question is this: Is there any way to find out who he sells it to, and for how much and finally, how much crop he picked? He has never given us documentation, and I feel we might be getting ripped off.