Section 2(1) of the Principal Act is hereby amended by -
(a) the insertion after the definition of "occupational injuries insurance" of the following definitions:
"'optional contribution' means a contribution paid under Chapter 4A of Part II;
'optional contributor' means a person engaged in share fishing paying optional contributions;",
(b) the insertion after the definition of "pensionable age" of the following definition:
"'person engaged in share fishing' means a self-employed contributor who is a member of the crew of a fishing vessel and whose principal means of livelihood is derived from a share in the profits or the gross earnings of the working of the vessel;",
(c) the substitution for the definition of "qualifying contribution" of the following definition:
"'qualifying contribution' means the appropriate employment contribution or self-employment contribution which was paid or would have been paid but for section 10(1)(c) or (d) or section 18(1)(d) in respect of any insur