It seems public health recommendations where walked back after the controversy in the early 2010's, so it is not an official recommendation anymore.

Here are some of the studies and debates from back then:

- Chronic Consumption of Farmed Salmon Containing Persistent Organic Pollutants Causes Insulin Resistance and Obesity in Mice (2011): https://journals.plos.org/plosone/article?id=10.1371/journal...

- Are environmental pollutants in the Norwegian diet harmful to children?: https://tidsskriftet.no/en/2017/02/perspectives/are-environm...