My question is why isn't fish farming done in closed circulating water pens.
-what are the issues or problems in doing so?
-Is anyone considering (or has) doing this presently, like to hear from you.
-In doing so would solve the sea lice problems, eliminate all excess mess that builds up under present open net pens, would reduce fish stress, easily moving fish (or harvesting) from one system to the next, increased flow rates at feeding times, decreased flow at night. Eliminate fish losts into the wild fish stocks. Why isn't their more interest in closed pens, what are the issues to farm fish this way? Is the cost of water flow a issue here? I believe it would easily done.

At this time the technology isn't there for saltwater fish like salmon - although many companies continue to trial new technology. Fish welfare, energy consumption and saltwater filtering systems are the questions that need answers.
In addition, it would be too expensive for Alaska to "close contain" the 1.5 billion ranched salmon they farm.