I did not realize the author of those websites is the same person.
I found a sentence about the co-authors of the 「山峡の釣」Mountain Gorge Fishing book.
But I wasn’t sure how to divide the names into separate names. 黒澤榮 鈴木魚心 共著. Or even if they should be. An internet search with the names didn’t find anything I recognized as being related.
I think a lot of information about the history and traditions of mountain stream kebari fishing, that excludes the story of the tenkara professional angler, the `Shoku ryōshi’「職漁師」, will only be found in old books, such as the 「山峡の釣」book. Information that is not yet, and may never be digitized, and that can be found via internet searches. I believe Clifford Stoll is correct when he wrote in his book, Silicon Snake Oil, that a subject has not been sufficiently researched if only online documents have been searched. A lot of information will only be found in books, magazines or journals.
And much of the story was probably never written down at all. Maybe only oral tales of the story existed, now lost.
That being said I have tried all of the below search phrases. Just to see what I might find. Many of the search results are interesting, but not turning up a lot of the story of the transition of kebari fishing traditions and methods from ancient times to modern sport.
日本古来の渓流毛鉤釣り, Ancient Japan’s Mountain Stream Kebari Fishing.
日本古来の渓流毛鉤釣り・伝承, Ancient Japan’s Mountain Stream Kebari Fishing Lore
和風古来の渓流毛鉤釣り・歴史, Ancient Japanese Style Mountain Stream Fishing History
和風古来の毛鉤釣り・歴史, Ancient Japanese Style Kebari Fishing History
和式古来の毛鉤釣り・歴史, Ancient Japanese Style Kebari Fishing History
渓流毛鉤釣り資料館, Mountain stream kebari fishing museum
源流毛鉤釣り資料館, Headwaters kebari fishing museum
源流毛鉤釣り・伝承, Headwaters kebari fishing - lore (or traditions)
日本古来の人気の毛鉤釣り方法, Ancient Japan’s popular kebari fishing methods
日本古来の人気の毛鉤釣り・歴史, Ancient Japan’s popular kebari fishing history
毛鉤釣り古伝, Kebari fishing legends [古伝 will also translate as fables, or ancient history]
古来の毛鉤釣り・経緯, Ancient times kebari fishing circumstances (or situation)
And many other combinations of terms. Just to see what might turn up in the search results.
A lot of my Japanese grammar is no doubt incorrect, but maybe good enough.