There's one big factor that would be at play in establishing a closed-containment aquaculture plant, and that would be the price of land. A closed-containment plant would require quite a large piece of land. If you're close to the urban centres, you're going to pay more for your land than you would pay near the coast, so that could be a big factor. Access to power generation is also expensive, as is the access to water.
I know that many times with various projects it's important to be able to use gravity to get the water to flow to the plant and out of the plant rather than having to pump it, because that will increase the costs.