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In 2007, the Ad Hoc Working Group on Tagging Coordination (Anon, 2008) adopted a new standardized system of numbering "A3N6" (three capital letters and six digits with no spaces) of conventional and electronic tags for highly migratory species, thus extending the current "A2N6" system and solving some of the problems of tag duplication for current existing tags.
The publication on the web page and the management (reservation, registration and inventory) of the tag codes was assigned to the ICCAT Secretariat by the SCRS.

The procedure was defined as voluntary (although strongly recommended by the SCRS). The inventory can be accessed and contributions can be made by any researcher who is associated or not with TUNA-ORG organizations. Additional details can be found in the abovementioned report.

  • Standardize the numbering of conventional tags used for tuna and tuna-like species.
  • Avoid tag duplication at sea among the programs that adopt this standard.
  • Have access to an updated inventory always available for the scientific community.
  • Field: All the conventional and electronic tags (archival, telemetry and satellite) used for large pelagics (tuna, tuna-like species, sharks, etc.).

    Numbering system: "A3N6" (9 alphanumeric characters): 3 alphabetical characters (∀A∈{A…Z}) in capital letters, and 6 digits (∀N∈ {0…9}). Some examples are as follows: AAD015015, BHH128300, JJJ000234.


    1. No spaces or particular characters in any position.
    2. "A3" (3 alphabetical characters) always in capital letters.
    3. "N6" (6 digits) always adding “zeros” if necessary in front.
    4. "O" and "I" are not used to avoid confusions with 0 and 1, respectively.
    5. All the code that start with "H" are reserved to reclassify the historical tags (developed with the following nomenclature "H2N6", "H2N5", etc.).
    6. All codes that start with "AR" are reserved for conventional tags that indicate the presence of an internal archival tag.

    Each code (approx. 323combinations = or 910 codes in total) has 106 unique numbers available and is divided in sets of 5,000 tags (200 sets for each code). Each set is always a multiple of 5,000 and its numbering is sequential. (1: 0 to 4,999; 2: 5,000-9,999; 3: 10,000-104,999;…; 200: 995,000-999,999).

    Researchers and institutions that wish to reserve a particular code, will have to previously:

    1. Select one of the available codes. It is not necessary to follow an order of availability, but it is recommended to follow the normal alphabetical order (AAA, AAB, AAC,..., BAA, BAB, BAC, etc.,) when selecting a code.
    2. Contact your TUNA-ORG organization and request the reservation (total or partial) of the previously selected code using one of the following:
      • Reservation of a complete code (106 tags): Used by Institutions that carry out continuous tagging and prefer to reserve a specific code (long term). In these cases they will have to inform the Secretariat once the tags have been manufactured (1 or more sets), always numbered in sequence.
      • Reservation and registration of part of the code: Used by specific scientists or institutions that carry out sporadic tagging (short term). In this case, notification of the amount of tags that want to be registered will be carried out (1 or more sets, always multiple of 5000) of the selected code.
    3. The person who is interested should include all the pertinent information in the reservation request (objectives, tag characteristics, institutions involved, responsible scientists).

    The “TUNA-ORG” organization that received the request will inform on the situation of the reservation as soon as possible and could request slight modifications to the proposal or additional information.

    To make a reservation at the ICCAT Secretariat use the following mail:

    Table 1: Codes currently reserved and registered in the inventory.

    A1 Codes Sets Quantity Institution (or Entity) Person responsible (Scientist) Registered by (RFMO)
    A AAA 1-200 (000000-999999) 1000000 AZTI Igor Arregui
    A AAB 1-200 (000000-999999) 1000000 FIPSAS (Federazione Italiana Pesca Sportiva ed Attività Subacquee) Antonio Di Natale
    A AAC 1-200 (000000-999999) 1000000 AZTI Igor Arregui
    A AAS 1-200 (000000-999999) 1000000 ICCAT Secretariat ICCAT
    A AP* 1-200 (000000-999999) 1000000 Apex Predators Program USA
    A AR* 1-200 (000000-999999) 1000000 Assigned to associated archive tags (no reservations made to date) --- ---
    A ASC 1-200 (000000-009999) 10000 Conservation Office, Ascension Island Government Andy Richardson
    A ATP 1-200 (000000-999999) 1000000 AOTTP (Atlantic Ocean Tropical Tuna Tagging Programme) Doug Beare
    B BCS 1-200 (000001-000600/000701-001000) 900 Indian Ocean BCSS Tagging Programme Mario Lebrato
    B BYP 1-200 (000000-999999) 1000000 GBYP (Atlantic Wide Research Programme on Bluefin Tuna) Francisco Alemany
    G GB* 1-200 (000000-999999) 1000000 Environment and Natural Resources Directorate, St Helena Government Rhys Hobbs
    H H** 1-200 (000000-999999) 1000000 RESERVED --- ICCAT
    P PAR 1-200 (000000-999999) 1000000 Assigned to associated Pop-up archive tags (0-4999 reserved) --- ---
    S SEC 1-200 (000000-999999) 1000000 ICCAT Secretariat ICCAT
    T TRE 1-200 (000601-000700) 100 Titan Red Challenge Tagging Programme Mario Lebrato
    Note: A1, First letter of the code. The character " * " indicates any letter from A-Z (excluding I and O).

    Table 2: Summary of the current situation (availability/reservations) by sets of codes (up to 2019-04-29).

    A B C D E F G J K L M N P Q R S T U V W X Y Z
    A1 A 4 23 23 1 1
    B 1 1
    G 23
    H Reserved for historical use
    I Not used
    O Not used
    P 1
    S 1
    T 1
    Note: Each cell of the table is equivalent to 23 codes and the number indicates the number of codes that have been reserved (available = 23 – those reserved).
    • Marcas no disponibles Unavailable (reserved)
    • Marcas reservadas Total reserved (0 available)
    • Marcas reserva parcial Partially reserved (some available)
    • Marcas libres 23 codes available