50 CFR § 300.5 - Facilitation of enforcement.
(a) Compliance. The operator of, or any other person aboard, any fishing vessel subject to this part must immediately comply with instructions and signals issued by an authorized officer or CCAMLR inspector to stop the vessel, and with instructions to facilitate safe boarding and inspection of the vessel, its gear, equipment, fishing record (where applicable), and catch for purposes of enforcing this part.
(1) For the purposes of this section “freeboard” means the working distance between the top rail of the gunwale of a vessel and the water's surface. Where cut-outs are provided in the bulwarks for the purpose of boarding personnel, freeboard means the distance between the threshold of the bulwark cut-out and the water's surface.
(2) For the purposes of this section, “pilot ladder” means a flexible ladder constructed and approved to meet the U.S. Coast Guard standards for pilot ladders at 46 CFR subpart 163.003 entitled Pilot Ladder.
(b) Communications.
(1) Upon being approached by a USCG vessel or aircraft, or other vessel or aircraft with an authorized officer or CCAMLR inspector aboard, the operator of a fishing vessel must be alert for communications conveying enforcement instructions.
(2) VHF-FM radiotelephone is the preferred method of communicating between vessels. If the size of the vessel and the wind, sea, and visibility conditions allow, a loudhailer may be used instead of the radio. Hand signals, placards, high frequency radiotelephone, voice, flags, whistle or horn may be employed by an authorized officer or CCAMLR inspector, and message blocks may be dropped from an aircraft.
(3) If other communications are not practicable, visual signals may be transmitted by flashing light directed at the vessel signaled. USCG units will normally use the flashing light signal “L” which, in the International Code of Signals, means “you should stop your vessel instantly.”
(4) Failure of a vessel's operator promptly to stop the vessel when directed to do so by an authorized officer or CCAMLR inspector, or by an enforcement vessel or aircraft, using loudhailer, radiotelephone, flashing light, flags, whistle, horn or other means constitutes prima facie evidence of the offense of refusal to allow an authorized officer or CCAMLR inspector to board.
(5) A person aboard a vessel who does not understand a signal from an enforcement unit and who is unable to obtain clarification by loudhailer or radiotelephone must consider the signal to be a command to stop the vessel immediately.
(c) Boarding. The operator of a vessel directed to stop must:
(1) Monitor Channel 16, VHF-FM, if so equipped.
(2) Stop immediately and lay to or, if appropriate and/or directed to do so by the authorized officer or CCAMLR inspector, maneuver in such a way as to allow the safe boarding of the vessel by the authorized officer or CCAMLR inspector and the boarding party.
(3) Except for fishing vessels with a freeboard of 4 feet (1.25 m) or less, provide, when requested by an authorized officer or CCAMLR inspector, a pilot ladder capable of being used for the purpose of enabling the authorized officer or CCAMLR inspector to embark and disembark the vessel safely. The pilot ladder must be maintained in good condition and kept clean.
(4) When necessary to facilitate the boarding or when requested by an authorized officer or CCAMLR inspector, provide a manrope or safety line, and illumination for the pilot ladder.
(5) Take such other actions as necessary to facilitate boarding and to ensure the safety of the authorized officer or CCAMLR inspector and the boarding party.
(d) Signals. The following signals, extracted from the International Code of Signals, may be sent by flashing light by an enforcement unit when conditions do not allow communications by loudhailer or radiotelephone. Knowledge of these signals by vessel operators is not required. However, knowledge of these signals and appropriate action by a vessel operator may preclude the necessity of sending the signal “L” and the necessity for the vessel to stop instantly.
(1) “AA” repeated (.- .-) is the call to an unknown station. The operator of the signaled vessel should respond by identifying the vessel by radiotelephone or by illuminating the vessel's identification.
(2) “RY-CY” (.-. -.-- -.-. -.--) means “you should proceed at slow speed, a boat is coming to you.” This signal is normally employed when conditions allow an enforcement boarding without the necessity of the vessel being boarded coming to a complete stop, or, in some cases, without retrieval of fishing gear that may be in the water.
(3) “SQ3” (... --.- ...--) means “you should stop or heave to; I am going to board you.”