Per land-based farming - it's a known fact that the average salmon farm generates as much raw effluent (sewage) as a population of 40,000 humans and is not treated at all. Countless farms are popping up in oceans around the world. In addition are the biological hazards of sea lice infestations, escape, pesticides and hormone use etc.
If land-based farms would actually re-use their own water by treating it rather than dumping it into the aquifers and ground water table it would be an improvement over open seas farming - however we all know that commercial interests would never conduct their business in such a conscientious and costly manner while competition from unregulated farms in other countries (Faroe Islands, Chile, Australia, Ireland, New Zealand, Scotland, Norway, etc) floods the market with artificially colored and flavored meat.
The problem is this, like most commercial interests, is founded in greed not conscience and it's very difficult for the ethical business practitioner to survive.
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