50 CFR §635.29

1. (a)A person who owns or operates a vessel issued a permit, or required to be issued a permit, under § 635.4 may not transfer any tuna or tuna-like species, or other HMS, at sea or in port, regardless of where the fish was harvested, except as provided in paragraph (c) of this section.
2. (b)For the purposes of this part, “transfer” means the act of “transshipping” as defined at 50 CFR 300.301. Notwithstanding the definition of “harvest” at § 600.10, for the purposes of this part, transfer also includes, but is not limited to, moving or attempting to move a tuna that is on fishing gear or other gear in the water from one vessel to another vessel.