RE: Fresh water shrimp
Ugh, a life of nothing but farmed fish. I think I'd give up entirely.
Overfishing is a serious problem, no doubt about it. There are lots of sustainable harvests, though, so it's really a question of keeping an eye on what's considered a healthy run. I eat a lot of alaska salmon, as the runs are very vigorous, and the quality of the line-caught fish is very high. Columbia and Trask River salmon runs aren't as vigorous, but the limited commercial harvest produces some of the best fish ever, so I imbibe and periodically donate to habitat restoration causes. ;0)
My big concerns with finfish aquaculture are around where the poop goes and what happens when the imported genes mix with the native fish. The island paradise I live on is home to a salmon farm, and there's these big pens floating out in the sound, filled with thousands of salmon stacked gill-to-gill. Salmon farms generate immense amounts of salmonpoop, which has to go somewhere (and usually ends up causing algae problems in the near vicinity). They also spread disease, so most farmed salmon has to be dosed with subtherapuetic antibiotics, a la chicken, which isn't good from a food safety perspective, and these diseases can spread to wild fish swimming by.
The real concern though is intermingling of the gene pool. While strides have been made in breeding "sterile" triploid salmon, what's grown in the Pacific NW is primarily Atlantic Salmon, which are competitors for food and spawning resources with our local salmonids, already a pretty decimated bunch. When these pens fail, and they do, tens of thousands of hungry predators are unleashed on local ecosystems. Just like annoying neighbors, they eat your food, they trash your house and they sleep with your partner. *sigh* All in all, farmed salmon isn't doing anyone any favors, aside from driving down the price of ocean-caught fish for those of us who insist on it.
Eric, Planning A Salmon Lunch