Sources for environmentally sustainable shrimps/prawn

I've done some research and I have had some success in sourcing more environmentally sustainable sources of shrimp/prawn. Here is a quick synopsis of what I've found out....

1. US Farmed Shrimp. Some of these farms are located far away from the sea and are re-circulating, closed-water systems that rear the shrimp in tanks.
   Caveat : no clear way to know, as far as I can tell, where the shrimps are exactly farmed. As a reminder, typically shrimp farms are located on the coast causing significant environmental impact to susceptable coastal ecosystems.
2. Organic shrimp. In the absense of formal Shrimp Aquaculture certification, there are a few shrimp farms that are certified organic, these do aim to supply shrimp without the use of chemicals, antibiotics, hormones or preservatives. Some of these farms are located in Florida and Ecuador.
   Caveat : Certified Organic doesn't necessarily mean environmentally sustainable.
3. Spot shrimp. Caught in temperate seas off Alaska using Traps.
   Caveat : Signs of overfishing. British Columbia shrimp fishery 'is fully fished, status of other fisheries is unclear' source - Seafood choices alliance

Another finding of note is that attempts in Thailand to place shrimp farms away from susceptable coastal areas suffered a set back with the Thai government banning this practice since 1999. The reason was that the waste from the shrimp farms left potential farm land ruined. Typical shrimp farms typically only work for a few years before the land has to be abandoned. It has been estimated that to return the land back to 'normal' takes 30 years. Source : Wikipedia

All in all not really a pretty picture. I continue to avoid shrimps or prawns.