The “at sea” requirement must be construed in context and in such manner as to accomplish the statutory objective. The section 13(a)(5) exemption is for the “catching, taking, propagating, harvesting,” etc., of “aquatic forms of animal and vegetable life.” There is no limitation as to where these activities must take place other than, as the legislative history indicates, that they are “offshore” activities. Since the purpose of the 1961 amendments is to exempt the “first processing, canning, or packing such marine products at sea as an incident to, or in conjunction with, such fishing operations,” it would frustrate this objective to give the phrase “at sea” a technical or special meaning. For example, to define “at sea” to include only bodies of water subject to the ebb and flow of the tides or to saline waters would exclude the Great Lakes which obviously would not comport with the legislative intent. On the other hand, one performing the named activities of first processing, canning, or packing within the limits of a port or harbor is not performing them “at sea” within the meaning of the legislative intent although the situs of performance is subject to tidewaters. In any event it would not appear necessary to draw a precise line as to what constitutes “at sea” operations, for, as a practical matter, such first processing, canning, or packing operations are those closely connected with the physical catching of the fish and are performed on the fishing vessel shortly or immediately following the “catching” and “taking” of the fish.