Any owner of shellfish grounds, franchise or franchises lying within the exclusive jurisdiction of the state, on or before the first day of July, annually, shall deliver to the Commissioner of Agriculture a statement under oath of such franchise or franchises or grounds belonging to such owner on the first day of June next preceding. Such statement shall specify the lot or lots owned by such owner by numbers as appear upon the last official map published by said commissioner, or, if granted since the publication of such map, according to such number as may be furnished by said commissioner, and the location and number of acres of each lot. Blanks for such statement shall be prepared by said commissioner and furnished to each owner, but failure to receive such blanks shall not relieve any person from the obligation to furnish the statement herein provided for. The commissioner may issue subpoenas to compel the attendance of any person before him, with books of account, documents and maps, and may administer oaths to and examine any person for the purpose of ascertaining the amount and value of such property. Any person who fails to respond to any such subpoena or who, having responded, refuses to testify or who fails to produce any such book or books of account, documents or maps, upon application of said commissioner to the superior court for any judicial district bordering on the waters of Long Island Sound, may be punished for contempt. Said commissioner may exercise the authority of assessors of towns and add ten per cent of the value of the property as a penalty for failure to give in a list. Any person who discloses any information obtained from any such witness or from the books or records of any such owner provided for under the provisions of this section, otherwise than in carrying out the provisions hereof, shall be fined not more than five hundred dollars.