The report about Sea-lion hunging on Takeshima dates back to two weeks before the famous Battle of Tsushima which almost ended around Takeshima on 28th May 1905. This is one of the good evidence not only that incorporation was not "secret" at all, but also people of Shimane has already know the fact of incorporation very well.
"●Sea-lion Hunting on Takeshima
As you readers have already know, Takeshima is a solitary island far off in the sea which locates 85 sea-ris north-west of Oki country and one of the island is around 20-chou(町), the other is merely aounrd 12-chou. Mr. Nakai Yonesaburo first voyaged tothe year before last and found the colony of Sea-lion. He found it is a pity that the island is omitted from the sea-chart, and petitioned to the national government. Through the good offices of Mr. Nakai, the islands were determined as the territory of the empire and incorporated into our Shimane prefecture by the Prefectural Order on 22 Feb. Ths islands are, as were described above, a meeting place of sea-lions for three months from May to July. Now apart from Nr. Nakai, three more rivals has emerged. Then they publised the licence only to those four and is going to let the four to hunt cooperatively. Furthermore, from what I hear, the period of time above are the period of their deivery, so the female are on the land for nurcing the baby, and male also land for the love of female. This is convenient for hunting. 7-8 thousand of sea-lion are on the same zone, tops, but excessive hunting would damage their reproduction. So the number of hunting is limited to 6-7 hundred per year so that they would make a profit for 5-10 years."
讀者も知れる如く、竹島は隱岐國の西北八十五海里にある絕海の孤島 にして、一は周回二十町、他の一は同上十一二町に過ぎず。這(こ)は、西鄕の中井米三郎氏が一昨年始めて渡航し、海獺の集合地なることを發見せしも、海圖 に洩れたるを遺憾とし、中央政府に稟申(りんしん)する等、大に斡旋の勞を執りし結果、帝國の領土とすることに決定し、去る二月廿二日の縣告示を以て、本 縣の管轄に歸せしものなるが、同島は實に前記の如く海獺の集合地にして、其期は五月より七月まで三ヶ月間なるが、今は同氏の外に三人の競爭者を生じたるを 以て、其向(そのむき)にては右四人の外には可か(きよか)を與へず、四人も亦共同して獵せしめん方針なりといへり。尙ほ聞く所に據れば右の期間は、海獺 が分娩するときにして、牝は哺乳の爲め陸地に上り、牡は牝を戀ひて上陸するものにして、銃殺に好便を與ふる次第なるが、多く上陸しるときには一區域にても 尙ほ七八千頭を下らす。然れども濫獲は生殖を害するを以て、一年凡そ六七百頭を限りなば、尙ほ五年や十年の利益を保持し得べしとのこと。
The article says the man's name was Yonesaburo, but it is Yozaburo or Yosaburo, in fact. San-in Shimbun(山陰新聞) is a local newspaper in Matsue, and now it called San-in Chuo Shinpo(山陰中央新報).
The article was founded and provided by Mr. Magic Eye, who is a good researcher and a collector of those historical stuff. Thank you for sharing a good information with us !