Sometimes you can see the results.

From the Friends of the Eel River:

Van Arsdale Fish Count Station

November 19, 2012
A total of 1,271 Chinook salmon entered the station this past week.  The season total stands at 1,904: (1,013 male, 578 female, 313 jacks). On November 18, the single day record was broken: 765 fish were counted.