(4) Fish unmolested in any of the waters of state with dredging apparatus, seines, nets, trawls, beam trawls (butterfly nets or wingnets), and all other instruments and apparatus for the sole purpose of obtaining the materials needed in the prosecution of the purposes and necessary investigations in the direction of the scientific objects for which this station is established. The secretary shall, in general, have all power and authority necessary to carry out the purposes and objects of this Subpart, namely, investigating the flora and fauna of the Gulf of Mexico and the waters adjacent thereto.