Standardized size-frequency data for albacore tuna (fork length, cm)

Each year, the IOTC Secretariat prepares a reference size data set for each IOTC species to provide information on the size composition of their catch in the IOTC area of competence. The data are collected on land by enumerators during unloading and transshipments and at sea by fishers and scientific observers from the IOTC Contracting Parties and Cooperating Non-Contracting Parties (CPCs) as per IOTC data requirements (IOTC Resolution 15/02). The data are submitted on an annual basis, mostly with the forms 4SF, and curated by the Secretariat for dissemination prior to the IOTC working groups.

Global attributes

• Title: Standardized size frequency data available in the IOTC database for Albacore
• Summary: Curated data set providing information on size composition
• Context of development: Management of tuna and tuna-like species under IOTC mandate
• Data origin: Size samples collected on land or at sea by national institutions and fishing industry that may be extrapolated to the fishery
• Lineage: Formatting, filtering, and conversion of size data submitted to the Secretariat (Data processing)
• Keywords: Albacore, length, selectivity, size, tuna fisheries
• Type: Tabular file
• Format: Microsoft XLSX
• Size: 10,273 KB
• Structure: 22,867 rows x 166 columns
• Taxonomic referential: ASFIS
• Geographic description: Fishing areas within the IOTC area of competence
• Spatial extent: 20° to 160° longitude and -50° to 25° latitude for regular grids
• Temporal extent: 1965-2022
• Temporal extent start date: 1965-01-01
• Temporal extent end date: 2022-12-31
• Associated rights: Public-domain data requiring source acknowledgment
• Spatial resolution: GRID10x20, GRID20x20, GRID1x1, GRID5x5, FAOSTAT (see Spatial resolution)
• Geographic referential: CWP grids with approximation for some fishing areas (see spreadsheet IRREGULAR GRIDS)
• Temporal resolution: Less than one year (see Temporal resolution)
• Temporal referential: ISO8601
• Update frequency: Once per year
• Metadata production date: 29 January 2024
• Source: IOTC
• Contact: [email protected]
• Credit: IOTC Secretariat

Data processing

The document IOTC-2020-WPDCS16-16 describes the processing steps applied to the size data sets managed at the IOTC Secretariat:

1- Removal of all sizes reported with an interval larger than the maximum interval value (Size measurement features)

2- Conversion of all sizes into standard measurement type with reference to conversion methods available in IOTC-2022-WPTmT08(AS)-DATA11

3- Distribution of the number of fish reported in intervals larger than the standard interval (Size measurement features) into equally spaced smaller intervals

4- Assignment of all standard lengths smaller than the minimum standard length class to the minimum standard length class (Size measurement features)

5- Removal of all standard lengths larger than the maximum standard length class.

Size measurement features

Fields

Contents

Code lists