Datasets

The IOTC Secretariat maintains a range of fisheries datasets submitted by Contracting Parties and Cooperating Non-Contracting Parties (CPCs), in accordance with the Commission’s data reporting obligations established under Resolutions 15/01 and 15/02. These datasets include retained catches by species and gear, geo-referenced catch-and-effort data, size-frequency measurements, and information on fishing vessels. Additional datasets cover time series on fishing fleet characteristics and fish and crude oil prices. The dissemination of these data is governed by the rules set out in Resolution 12/02, ensuring both transparency and appropriate safeguards. The data underpin scientific stock assessments, compliance monitoring, and the formulation of management advice within the IOTC framework.

Most Recent Datasets Released by the IOTC Secretariat

Other datasets available at the IOTC Secretariat

Tagging Data

Some earlier tagging experiments focusing on skipjack and yellowfin tuna were conducted in the Indian Ocean around the Maldives in 1990–1991 and 1993–1995, with support from the Indo-Pacific Tuna Tagging Programme. Between 2005 and 2009, a large mark–recapture dataset for the principal tropical tuna species of commercial interest -- bigeye tuna, skipjack tuna, and yellowfin tuna -- was collected through the implementation of an EU-funded Regional Tuna Tagging Programme (IO-RTTP), together with several smaller tagging projects. An overview of the tagging programme and its scientific results supporting the management of tropical tunas in the Indian Ocean is available in a special issue of the journal Fisheries Research (Murua et al. 2015).

The policy governing the release of tagging data is established under IOTC Resolution 12/02 on Data Confidentiality Policy and Procedures. Annex 1 of the Resolution provides a Tagging Data Users Application Form, which must be submitted to the IOTC Secretariat to request access to the dataset.

Biological and Morphometric Data

The IOTC Secretariat holds datasets and information on morphometric relationships and selected biological characteristics of IOTC stocks and related species. These include:

• Morphometric relationships and conversion factors used to convert non-standard measurements into standard measurements
• Data on the proportion of specimens by sex (sex ratio)
• Data on maturity and fecundity of IOTC and related species
• Additional datasets, such as those used to derive growth functions for IOTC stocks based on otolith readings.

Stock Assessment Data

Please refer to the meeting pages of each Working Party to consult and download the datasets that were used for stock assessment:

• WP on Billfish (WPB)
• WP on Neritic Tunas (WPNT)
• WP on Temperate Tunas (WPTmT)
• WP on Tropical Tunas (WPTT)
• WP on Ecosystems and Bycatch (WPEB)

For further information on the datasets available and the procedures for obtaining access, please contact the IOTC Secretariat.

Catch Limits for Tropical Tuna Species

The tables below summarise catch limits established by the IOTC for the principal tropical tuna species in the IOTC Area of Competence. These limits are adopted by the Commission through binding management measures and are allocated to CPCs in accordance with the relevant IOTC Resolutions.

For yellowfin tuna and bigeye tuna, the limits presented here are derived from the provisions of IOTC Resolution 19/01 and IOTC Resolution 21/01 for yellowfin tuna, and IOTC Resolution 23/04 and IOTC Resolution 25/04 for bigeye tuna. These measures establish total allowable catch levels and/or reduction requirements and define the catch limits applicable to CPCs for the relevant management periods.

Catch limits for skipjack tuna are established under IOTC Resolution 25/03 and will be presented once the revised calculation methodology adopted by the Commission has been reflected in the official tables.

Bigeye Tuna

Table 1. Catch limits (metric tonnes; t) applicable in 2025 and 2026 for CPCs subject to IOTC Resolution 23/04 and IOTC Resolution 25/04 for Indian Ocean bigeye tuna (IOTC Circular 2025-44)

Yellowfin Tuna

Table 2. Catch limits (metric tonnes, t) applicable in 2025 (calculated) and 2026 (estimated) for CPCs subject to IOTC Resolution 21/01 for Indian Ocean yellowfin tuna. The limits for 2026 are estimated on the assumption that catches in 2025, which are not yet available, will not exceed the applicable limit for that year (IOTC Circular 2025-44)