The owner, charterer, managing operator, agent, master, or individual in charge of a fish processing vessel of more than 100 gross tons as measured under
section 14502 of this title, or an alternate tonnage measured under
section 14302 of this title as prescribed by the Secretary under
section 14104 of this title shall keep a suitable number of watchmen trained in firefighting on board when hotwork is being done to guard against and give alarm in case of a fire.