GBYP

GBYP Phase 14 was successfully completed in December 2025. The main results of the activities carried out along 2025 are summarized below. Phase 15 started in February 2025, and will run for 23 months (until December 2027).

Highlights from September 2025 and expected achievements for 2026 are summarized below. These are critical to refining stock assessments and strengthening science-advice for management of Atlantic bluefin tuna:

Pole applicator for the underwater deployment of acoustic tags on bluefin tuna (off southern Portugal, May 2026).

Data Systems: Significant developments were made on the biological and electronic tagging information systems (databases) stored the ICCAT Secretariat infrastructure. The ETAGS database will be fully operational by the end of the year with the upload of all the tracking data. Aerial Surveys: The eastern stock abundance index time series was updated incorporating the results from 2025 survey carried out in the western Mediterranean (Balearic Sea). A new aerial survey is planned for June 2026, together with additional standardization work of the index for accounting for environmental variability and the modelling tasks to get an improved index time series has been initiated. Tagging: Five new MoUs to deploy up to 110 electronic tags in the Mediterranean and Eastern Atlantic (70 archival tags and 40 acoustic transmitters) have been signed. The first acoustic tagging campaign took place off the southern cost of the Algarve (southern Portugal). Biological Studies: New genetic studies have been completed under Phase 14, which contributed to improving the knowledge on bluefin tuna population’s structure, as well as on mixing dynamics of Atlantic populations. Further studies to develop new tools (epigenetic clocks) for ageing have been initiated. Modelling: Two studies aimed at testing the impact of new information on absolute biomass of western bluefin tuna stock and on potential impact on the periodicity of abundance indices derived from aerial surveys on management strategy evaluation (MSE) were completed under Phase 14. A new contract has been awarded in 2026 to perform a bluefin stocks status/health check.

Additional information can be found here.

ALBYP

Significant progress has been made regarding biology, movement, and management strategy evaluations (MSE).

Reproduction and Growth:

• A new contract on albacore reproduction in the North Atlantic has been signed, aiming at the conclusion of the study during 2026.
• For the South Atlantic a new contract has also been signed with a research team from Brazil to proceed with processing and analyses of new samples collected (by Brazil, Namibia, South Africa, and Chinese Taipei), which will allow the conclusion of the study in 2027.
• Preliminary results from ongoing studies have shown possible bias when estimating growth parameters based on readings from spine samples. Further research is needed, which shall include samples from juveniles.
• A new study has estimated ages of up to 18 years for albacore tuna, with at least one estimate validated using bomb-radiocarbon (14C). Despite these findings, the maximum age of 15 years will be maintained for the assessment, until further results from an ongoing ICCAT contract become available.

Movements & Habitat Use:

• Over 270 electronic tags have been deployed, of which 73 have transmitted data and/or were recovered. Of those, 225 corresponded to internal archival tags, of which 21 were recovered in 2025).
• New campaigns are planned from June to December 2026, in both the North and South Atlantic, aiming at albacore electronic tagging.

Management Strategy Evaluation (MSE):

• A new MSE process is ongoing for the South Atlantic albacore, with preliminary Operating Models (OMs) and preliminary projections testing of six Candidate Management Procedures (CMPs), were recently presented to the SCRS.
• For the North Atlantic, the Commission has requested the SCRS (via Panel 2 March meeting) further investigations, which recently discussed three CMP types. The plan for this MSE involves improving the index-based parameters, conducting thorough robustness testing, and updating the Trial Specification Document.
• A new potential Exceptional Circumstances Protocol (ECP) affecting the MP will be reassessed by the SCRS in September 2026, to take into account the 2025 data.

Preliminary results regarding the proportion of mature individuals by age for (A) sexes combined, (B) females and (C) males for the northern Atlantic albacore.

Additional information can be found here.

SMTYP

Since 2018, this programme has coordinated biological sampling of small tunas - little tunny (LTA), Atlantic bonito (BON), and wahoo (WAH), bullet (BLT) and frigate (FRI) tuna, among other species. The current contract engages a consortium of 20 entities from 13 Contracting Parties.

Objectives:

• Fill size gaps for growth and maturity estimates for BON, LTA, WAH and collecting additional samples for FRI and BLT in the Atlantic and the Mediterranean Sea.
• Determine growth and reproduction parameters for BON, LTA, WAH, FRI, and BLT.
• Refine stock structure analyses for BON, LTA, WAH, FRI and BLT species.
• Investigate genetic differentiation between FRI and BLT.

Results and updates have been presented during intersessional meetings. Priorities for 2026–2029 include:

• The update of the biological meta-database and the new biological sampling is ongoing, as well as the estimation of length–weight relationships at stock/regional levels.
• New advances have been presented regarding the bullet and frigate tuna, with preliminary genetic results suggesting that the bullet tuna is the dominant species on temperate waters of the Northeastern Atlantic and the Mediterranean Sea, with an increasing level of mixing towards the tropical waters, namely in the Gulf of Guinea. There is also a high level of misidentification, due the resemblance of the two species.
• Growth parameters have been presented for the LTA, BON, and WAH species. Work is currently underway to establish a reference dataset for these species.
• A specific working group has been created to develop data-limited methods for management advice.
• The coordination and management tasks have been reinforced with the enhancement of the ICCAT Secretariat support to these SMTYP tasks.

Capacity-building on small tuna species identification and collection of biological samples in Angola.

Additional information can be found here.

EPBR

This programme was originally designed to collect catch/effort data and support tagging and ageing studies, the programme has since expanded to include habitat use and migrations and spawning.

Key highlights:

• Sample collection: Since 2019, 781 biological samples of BUM, WHM, and SFA have been collected in the eastern Atlantic, by teams from West Africa countries and EU-Portugal. A bomb-radiocarbon validation study is ongoing for blue marlin using otoliths, with preliminary results supporting current age estimations. Sample collection, ageing and bomb-radiocarbon work will continue throughout 2026.
• Tagging: Since 2023, satellite and conventional tagging has been carried out in the eastern Atlantic, with 11 white marlins and three blue marlins tagged off the southern Portuguese coast and two sailfish tagged off São Tomé e Príncipe, plus 31 conventional tags deployed on white marlins. Preliminary results point to important large-scale transatlantic and inter-hemispheric migrations. Tagging campaigns will continue throughout 2026.

Location of electronic tags deployment and tag pop-up for the three billfish species.

Additional information can be found here.

SRDCP

The Shark Species Group advanced key studies since the last Newsletter, including those regarding the following:

Age & Growth:

• The collaborative study on South Atlantic shortfin mako allowed to provide relevant input for the 2025 Stock Assessment for the southern Atlantic stock.
• Age validation work is ongoing, including a study based on bomb radiocarbon techniques, to validate the growth band deposition periodicity throughout the lifespan and early growth of shortfin mako shark.
• Age and growth research also progressed for longfin mako, with vertebrae processing, and the collection of images and age readings underway.
  
  

Sagittal section of a vertebral centrum of a shortfin mako (Isurus oxyrinchus) shark female (fork length: 154 cm) from the South Atlantic. The yellow dot marks the birth mark and the red dots indicate each growth band. (Source: Márquez et al., 2025, document SCRS/2025/040).

• Genetics: Porbeagle genetics studies proceeded to further investigate the connectivity between the southeastern and southwestern Atlantic, as well as between the southern Atlantic and the Indian Oceans.

Tagging & Movements:

• Shortfin mako: Post-release mortality analysis has been updated, showing that 28% of the 128 shortfin mako sharks tagged with satellite tags died soon after being discarded live by pelagic longlines. The results have been incorporated in the South (2025) and North (2026) Shortfin Mako Stock Assessments. These results are also useful to respond to the Commission request on the retention allowance for shortfin mako.
• Other sharks: After the successful dedicated tagging campaigns in 2024 and 2025, which resulted on the deployment of 31 pop-up tags (including 12 silky sharks, 3 bigeye threshers, 2 longfin makos, 2 smooth hammerheads, 11 oceanic whitetip and 1 blue shark) in the equatorial area of the Atlantic, new tagging campaigns are underway on both eastern and western Atlantic areas.
• As part of a pilot project, mini data loggers (TDRs) have been deployed on the mainline and on the branchlines of longline fishing vessels, to register profiles of depth and depth/temperature for the operation of the longline gear, which have potential interactions with shortfin mako sharks.

Example of temperature records by depth intervales (coloured), collected by the TDRs deployed on longline gear.

These efforts are refining knowledge on shark biology, stock boundaries, habitat use, and mortality, and directly supporting more robust scientific advice aiming the adoption of conservation and management measures by ICCAT.

Additional information can be found here.

SWOYP

Launched in 2018, SWOYP brings together 23 institutions from 15 CPCs to reduce key uncertainties in swordfish biology and improve stock assessments and the MSE process. The programme focuses on ageing and growth, reproductive biology, genetics, and tagging, with nearly 4,900 swordfish samples collected across all three ICCAT-managed swordfish stocks.

• Age & Growth: New results have been presented for both northern and southern Atlantic stocks, which will be used during the ongoing Stock Assessment for the southern Atlantic stock. Age validation via bomb radiocarbon analysis remain underway, to help refine maximum age estimates and the catch-at-age data used by the SCRS on the provision of advice.
• Reproduction & maturity: Similarly, the achieved results recently presented to the SCRS allowed the size of maturity (L50) to be updated and will also be used during the ongoing Stock Assessment.
• Genetics: Additional work is underway on stock differentiation, identification of boundaries and mixing rates among the three swordfish stocks (ATL-N, ATL-S and MD). Available results showed a clear genetic separation between Mediterranean and Atlantic stocks, as well as differentiation between North and South Atlantic groups with evidence of mixing in the BIL94B area. These results are essential to address critical uncertainty in Atlantic swordfish science and management.
• Tagging: 56 satellite tags have been deployed since 2018 across the Atlantic and Mediterranean; recent campaigns in the north-eastern Atlantic and off Newfoundland have expanded knowledge of migration, stock mixing, and vertical habitat use. New tagging campaigns are scheduled for this summer.
• Fisheries: Following the Commission requests several Contracting Parties (EU-Portugal and EU-Spain; Japan), have reported preliminary results to the SCRS, on their ongoing studies regarding the use of traplines on pelagic longline fisheries. These reported the first quantitative evidence that traplines show differences in catch composition and catch per unit effort (CPUE) compared to standard pelagic longline gear used for targeting swordfish.

Swordfish sampling coverage for the North and South Atlantic, and Mediterranean Sean. Black dots represent swordfish catch for years 2019-2023 for each 5°x5° grid cell area, scaled by contribution to the overall catch. Coloured dots represent biological sample collection locations for phases 1 to 7 of SWOYP. Sampling locations have been jittered by 0.5°x0.5°.

Additional information can be found here.

TTRaD

This programme, which was launched in 2024, supports ICCAT tropical tuna management through data collection, tagging, age and growth studies, and MSE developments. In 2025, TTRaD focused on improving scientific advice, updating spatio-temporal models, and maintaining the Atlantic Ocean Tropical Tuna Tagging Programme (AOTTP) database.

Key Achievements:

• MSE & Stock Assessment: After the implementation of the western skipjack MP, the ongoing work relates to the development of an ECP.
• The development of the tropical tuna multi-stock MSE is underway, with the most recent work focusing on the observation error model and options for Harvest Control Rules (HCR) to simulate TAC and fleet effort adjustments.
• Age & Growth Studies: A joint-ICCAT-iTUNNES workshop was recently held in Pasaia (Spain) to advance current knowledge on age and growth and partially on reproduction of the three tropical tunas species (bigeye, yellowfin and skipjack). This collaborative and coordinated action aims updating growth parameters, and identify major data gaps and priority needs for future work, aiming the reducing uncertainty on the key parameters for the provision of scientific advice to the Commission.
• Fisheries statistics: Following recent discussions and concerns regarding the tropical tuna reported catches, the SCRS has set an ad hoc sub-group tasked with reviewing the tropical tuna catch composition and ICCAT Task 1NC statistics. The first report is planned to be provided during the September 2026 Species Group meeting.

These activities have helped to improve the data available to support future tropical tuna assessments and the development of the MSE processes, hence the SCRS advice to the Commission.

Additional information can be found here.

Voluntary Contributions

Since the last Newsletter (November 2025), the ICCAT Secretariat has received notification that during 2026 the following voluntary contributions will be made:

ICCAT/Japan Capacity-Building Assistance Project (JCAP-3)

As part of the new JCAP-3, since the last Newsletter, a number of training programmes and capacity-building activities have been carried out with the aim of strengthening national capabilities in fisheries monitoring, species identification, data collection and scientific research.