29 C.F.R. § 784.128
Requirements for exemption of first processing, etc., at sea
A complete exemption from minimum and overtime wages is provided by section 13(a)(5) for employees employed in the operations of first processing, canning, or packing of marine products at sea as an incident to, or in conjunction with “such” fishing operations—that is, the fishing operations of the fishing vessel (S. Rep. 145, 87th Cong., first session, p. 33). To qualify under this part of the exemption, there must be a showing that: (a) The work of the employees is such that they are, within the meaning of the Act, employed in one or more of the named operations of first processing, canning or packing, (b) such operations are performed as an incident to, or in conjunction with, fishing operations of the vessel, (c) such operations are performed at sea, and (d) such operations are performed on the marine product specified in the statute.