I subscribe to the RSS feed of GPO's Registry of U.S. Government Publication Digitization Projects at http://registry.fdlp.gov. Recently that feed alerted me to a repository of United States Fish Commission Annual Reports at http://docs.lib.noaa.gov/rescue/cof/data_rescue_fish_commission_annual_reports.html. 

Knowing that a good amount of Alaska related information can be found in pre-1959 federal documents, I had a look at a few reports. I was surprised to find that information about fox farming was included in the fish commission reports. It's true. Go look up the 1920 report and turn to page 64 in the PDF file.

Alaska had a number of island fox farms early in the 20th century. I've answered questions about them in the past, but would have never thought to look in a fisheries report for a land mammal.

Thanks to NOAA for digitizing these reports and thanks to GPO for keeping this Registry. Among other things it is a great tool for serendipitous discovery.