Based on average landings of petrale sole from 2011-2013 and using 2016 Seafood Watch ratings, the sustainability breakdown of North American petrale is as follows:

Within North America, British Columbia lands ~50% of North American petrale sole, Oregon lands ~30%, Washington and California ~10% each (~35-40% of California landings caught by the California Groundfish Collective).
FishChoice's petrale sole sustainable seafood guide

Plaza Aquafarms is a leading importer, farmer, wholesaler, and distributor of sturgeon caviar located in Wilton, California. Founded in 1989, Plaza Aquafarms and the Pacific Plaza Imports brand pride themselves on offering an alternative to either wild sturgeon or sturgeon caviar farm-raised with intensive chemicals. By investing in domestic, sustainable farming methods, Plaza Aquafarms has been able to alleviate the demand for imported caviar. Recognized as a world leader in sustainable sturgeon production, Plaza Aquafarms has become its own micro-ecosystem. Using proprietary tank-farming techniques, their aquafarm is able to recycle all of its water after passing it through natural aquifers - an on-site, five acre hydroponic pond. This whole process is designed to clean and recharge the waters so that their fish can swim in pristine and mineral rich waters. Read more...