About a fifth of the world’s annual wild fish catch, amounting to about 18m tonnes of wild fish a year, is used to make fishmeal and fish oil, of which about 70% goes to fish farms

https://www.theguardian.com/environment/2021/feb/11/global-salmon-farming-harming-marine-life-and-costing-billions-in-damage

Among other environment impacts too. All kinds of fish farms dumps lage amounts of waste into the environment

For a world annual shrimp production [in fish farms] of around 5 million tons, 5.5 million tons of organic matter, 360,000 tons of nitrogen, and 125,000 tons of phosphorous are annually discharged to the environment

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3353277/

  • Kogasa@programming.dev
    1·
    3 months ago

    What’s the ROI? If 15% of wild caught fish are used to support fish farms that produce twice as much, it’s not as obviously a bad thing. There’d need to be another food source though.

    • usernamesAreTricky@lemmy.mlOP
      1·
      3 months ago

      Going to almost certainly be less than 1. Moving further up the food chain results in energy losses. Those fish are going to use energy for their own body and such

      Moreover there’s high mortality rates inside of fish farms for fish themselves. From the linked earlier article

      Fish mortality has more than quadrupled, from 3% in 2002 to about 13.5% in 2019, in Scottish salmon farms alone. About a fifth of these deaths are recorded as being due to sea lice infestations, but about two thirds are unaccounted for so the real mortality owing to sea lice – which feed on salmon skin and mucus, effectively eating the fish alive – could be much higher.