The council may recommend minimum standards of apprenticeship and for related and supplementary instruction, encourage registration and approval of apprentice agreements and training programs, and issue certificates of completion upon the verification by employers or joint apprenticeship committees of the satisfactory completion of the term of apprenticeship. The council shall assist in recommending policies for the effective administration of sections 31-22m to 31-22q, inclusive, and 31-22u. Such policies by the council shall not invalidate any apprenticeship provision in any collective bargaining agreement between employers and employees. All apprentice programs adopted and registered with the Labor Department under said sections shall be on a voluntary basis and shall be installed for the purpose of developing skilled workers for the service trades and industries of Connecticut.