(a)  The Secretary of the Interior is authorized to lease, under such rules and regulations as he may deem proper, land ascertained by him to be suitable for home site purposes in the Kalapana extension as described in section 391b of this title, to native Hawaiians when such occupancy does not encroach on or prevent free access to any points of historic, scientific, or scenic interest or in any manner obstruct or interfere with protection and preservation of said area as a part of the Hawaii National Park: Provided, however, That occupants of homesites shall reside on the land not less than six months in any one year: And provided further, That fishing shall be permitted in said area only by native Hawaiian residents of said area or of adjacent villages and by visitors under their guidance.

(b)  The term “native Hawaiian”, as used in this section, means any descendant of not less than one-half part of the blood of the races inhabiting the Hawaiian Islands previous to 1778.