Transshipment means the unloading of fish from on board one fishing vessel and its direct transfer to, and loading on board, another fishing vessel, either at sea or in port. Fish shall be considered to be on board a fishing vessel once they are on a deck or in a hold, or once they are first lifted out of the water by the vessel. Net sharing is not a transshipment.
50 CFR § 300.211
In addition to the terms defined in 300.2 and those in the Act and in the Convention on the Conservation and Management of Highly Migratory Fish Stocks in the Western and Central Pacific Ocean, with Annexes (WCPF Convention), which was adopted at Honolulu, Hawaii, on September 5, 2000, by the Multilateral High-Level Conference on Highly Migratory Fish Stocks in the Western and Central Pacific Ocean, the terms used in this subpart have the following meanings.