Mass. Gen. Laws ch. 131 § 47
No riparian proprietor of a natural pond other than a great pond, or of an artificial pond of any size, or of a nonnavigable stream, shall enclose the waters thereof within the limits of his own premises unless he furnishes a suitable passage for all anadromous fish naturally frequenting such waters to spawn; nor shall any riparian proprietor enclose the waters of any such pond or stream for the purpose of artificial propagation, cultivation and maintenance of fish, except shiners as authorized in section fifty-two, unless he first procures a propagator's license under section twenty-three authorizing him so to do.
A person, without the written consent of the proprietor or lessee of a natural pond which is not a great pond, or of an artificial pond of any size, or of a nonnavigable stream, where fish are lawfully propagated or maintained under authority of a license under this chapter, shall not take, or attempt to take, fish therefrom.
Mass. Gen. Laws ch. 131, § 47