Geo-referenced size-frequency data - Bigeye tuna (BET)

This dataset corresponds to the size-frequency (SF) data for bigeye tuna (Thunnus obesus), classified by fishing fleet, year, gear, type of school, time interval (usually monthly), spatial stratum (typically CWP square grids of 5°×5°), and fork length class. The size data may originate from samples or have been raised to represent the total catch.

Size measurements have been consolidated following the processing steps described in IOTC-2020-WPDCS16-16. The conversion factors and morphometric relationships used to convert all size measurements to fork lengths are available in IOTC-2025-WPTT27-DATA08.

The data originate from the IOTC Contracting Parties and Cooperating Non-Contracting Parties (CPCs) as per the IOTC data requirements (Resolution 15/02). They are submitted annually, mostly using IOTC Form SF, and curated by the Secretariat for dissemination prior to IOTC Working Parties and other scientific data users.

Global attributes

• Title: Size-frequency data of bigeye tuna by fleet, 1965-2024
• Summary: Curated dataset providing detailed information on the size composition of the catch of bigeye tuna (Thunnus obesus) in the Indian Ocean
• Context of development: Management of tuna and tuna-like species under IOTC mandate
• Data origin: Size-frequency data collected on land or at sea by national institutions and the fishing industry, with some data having been previously extrapolated to represent the broader fishery
• Lineage: Data submitted by CPCs and consolidated
• Keywords: size composition, morphometrics, tuna fisheries
• Type: Tabular file
• Format: CSV
• Size:
  • 423,643 KB for original dataset
  • 10,415 KB for compressed dataset
• Structures: rows x columns for catch dataset
• Geographic description: Fishing areas within the Indian Ocean
• Update frequency: According to data revisions and updates
• Metadata production date: 17 October 2025
• Source: IOTC
• Data curator: IOTC Secretariat
• Contact: [email protected]
• Associated rights: Public-domain data requiring source acknowledgement

Data fields