What criteria should be used to shorten the list of references?
Reference limits aren't typically literally there to limit the number of references, they are there to limit the length and breadth of the Introduction and Discussion.
Rather than targeting specific references, look whether there are intro/discussion (I'd start with the intro) sections that aren't really needed, or can be consolidated to a brief statement and citation of a review. Probably if you are going as far as citing news articles you have too wide a view in the introduction.