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Standardised size-frequency data for bigeye tuna

Reference: 
IOTC-DATASETS-LATEST-SF-BET
File: 
Package icon IOTC-DATASETS-SF-BET-1965-2023.zip
Type: 
Datasets
Year: 
2024
Meeting: 
None
Meeting session: 
0
Availability: 
25 September 2024
Authors: 
IOTC Secretariat
Abstract: 

Each year, the IOTC Secretariat prepares reference size-frequency datasets 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 IOTC Form 4SF, and curated by the Secretariat for dissemination prior to the IOTC working groups.

 

Global attributes

  • Title: Standardised size-frequency data available in the IOTC database for bigeye tuna
  • Summary: Curated dataset providing detailed information on the length composition of tuna catch
  • 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 the fishing industry, with some data having been previously extrapolated to represent the broader fishery
  • Lineage: Formatting, filtering, and conversion of size data submitted to the Secretariat (Data processing)
  • Keywords: Bigeye tuna, length, selectivity, size, tuna fisheries
  • Type: Tabular files
  • Format: CSV
  • Size: 111,241 KB for melted dataset and 28,451 KB for pivot table dataset
  • Structures:
    • 1,623,356 rows x 16 columns
    • 70,132 rows x 165 columns
  • Taxonomic standard: ASFIS
  • Geographic description: Fishing areas within the Indian Ocean
  • Spatial extent: 20° to 130° longitude and -60° to 30° latitude for regular grids
  • Temporal extent: 1965-2023
  • Temporal extent start date: 1965-01-01
  • Temporal extent end date: 2023-12-31
  • Spatial resolution: Spatial resolution table
  • Spatial standard: CWP for regular grid areas
  • Temporal resolution: Temporal resolution table
  • Date standard: ISO 8601
  • Data quality: IOTC reporting quality scoring
  • Update frequency: At least once per year
  • Metadata production date: 23 September 2024
  • Source: IOTC
  • Contact: [email protected]
  • Credit: IOTC Secretariat
  • Associated rights: Public-domain data requiring source acknowledgement
 

Data processing

The document IOTC-2020-WPDCS16-16 describes the processing steps applied to the size-frequency data 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-2023-WPTT25(AS)-DATA13

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

6- Removal of data reported for areas not in the Indian Ocean

 

Size measurement features

  
Type of measurement codeLN
Measurement codeFL
Measurement unitcm
Default measurement interval2
Maximum measurement interval4
Minimum size10
Maximum size250
 

Dataset fields

FIELDDEFINITIONCODE LIST
FLEET_CODEIOTC legacy code for fishing fleetsFLEETS
YEARGregorian calendar year of the fishing activities reported through the dataset 
MONTH_STARTStart month of the fishing activities reported through the dataset 
MONTH_ENDLast month of the fishing activities reported through the dataset 
FISHING_GROUND_CODEIOTC code for fishing areasFISHING GROUNDS
GEAR_CODEIOTC legacy code for fishing gearsGEARS
SCHOOL_TYPE_CODEIOTC legacy code for types of fish school associationSCHOOL TYPES
SPECIES_CODEASFIS three-alpha code of the speciesSPECIES
MEASUREMENT_CODEIOTC code for morphometric measurementsMEASUREMENTS
FIRST_CLASS_LOWFirst length class (corresponding to class C001) 
SIZE_INTERVALInterval (cm) between consecutive fork length classes 
NO_FISHTotal number of fish reported 
KG_FISHTotal weight (kg) of fish estimated using IOTC length-weight relationship 
RAISE_CODEIndicates whether the size data are original or raised samplesRAISINGS
REPORTING_QUALITYIndicates the score of reporting quality estimated by the IOTC Secretariat 
C001…C150Size class indices 
 

Data contents

 

Reporting quality scores

Dataset

Criterion

By species

By gear

Size frequencies

Available according to standards

0

0

Not available according to standards

2

2

Low coverage (<1 fish per tonne caught)

2

Not available

8

 

Spatial resolution

Area type codeRaise codeStrataSamples
GRID01x01OS1,865631,522
GRID01x01SD40133,245
GRID05x05OS2017,107,573
GRID05x05SD83133,454,897
GRID10x20OS31874,509
GRID20x20OS13,889
IRREGAREAOS7139,871
IRREGAREASD22,737,008
 

Temporal resolution

Time period (mo)Raise codeSamples
1OS7,881,438
1SD134,521,569
3OS874,783
3SD1,703,581
7OS272
12OS871
 

Code lists

 

Fleets

FLEET_CODENAME_ENNAME_FR
AUSAUSTRALIAAUSTRALIE
CHNCHINACHINE
COMCOMOROSCOMORES
EUESPEU.SPAINUE.ESPAGNE
EUFRAEU.FRANCEUE.FRANCE
EUITAEU.ITALYEU.ITALIE
EUMYTEU.FRANCE.MAYOTTEUE.FRANCE.MAYOTTE
EUPRTEU.PORTUGALUE.PORTUGAL
EUREUEU.FRANCE.REUNIONUE.FRANCE.RÉUNION
GBRUNITED KINGDOMROYAUME-UNI
IDNINDONESIAINDONÉSIE
IRNIRAN ISLAMIC REP.IRAN RÉP. ISLAMIQUE
JPNJAPANJAPON
KORKOREA REP.CORÉE RÉP.
LKASRI LANKASRI LANKA
MDGMADAGASCARMADAGASCAR
MDVMALDIVESMALDIVES
MOZMOZAMBIQUEMOZAMBIQUE
MUSMAURITIUSMAURICE
MYSMALAYSIAMALAISIE
NEICENEI.FRESHNCA.FRAIS
NEIPSNEI.OTHERNCA.AUTRE
PHLPHILIPPINESPHILIPPINES
SYCSEYCHELLESSEYCHELLES
TWNTAIWAN,CHINATAIWAN,CHINE
TZATANZANIATANZANIE
ZAFSOUTH AFRICAAFRIQUE DU SUD
 

Gears

GEAR_CODENAME_ENNAME_FR
BBBaitboatCanne
BBOFBaitboat (offshore)Canne (hauturière)
ELLLongline targeting swordfishPalangre à espadon
ELLOBLongline targeting swordfish with observerPalangre à espadon avec observateur
FLLLongline freshPalangre fraiche
G/LGillnet and longline combinationFilet maillant et palangre
GILLGillnetFilet maillant
GIOFOffshore gillnetFilet maillant pêche hauturière
HANDHandlineLigne à main
HATRHand line and troll lineLigne à main et ligne de traîne
LIFTLiftnetCarrelet
LLLonglinePalangre dérivante au-dessus de 1800 hameçons
LLCOCoastal longlinePetite palangre
LLOBLongline with observerPalangrier avec observateur
PSPurse seineSenne tournante aux thons
PSOBPurse with observerSenne tournante avec observateur
PSSSmall purse seinePetite senne côtière
RINRing netLampara
RNOFRing net (offshore)Lampara (hauturière)
SPORSport fishingPêche sportive
TROLTroll lineLigne de traîne
UNCLUnclassifiedNon classé
 

School types

CATCH_SCHOOL_TYPE_CODENAME_ENNAME_FR
FDSchool associated with dolphinsBanc associé avec des dauphins
FSFree-swimming schoolBanc libre
LASchool associated with anchored Fish Aaggregating DeviceBanc associé à un objet flottant ancré
LSSchool associated with a drifting floating object, natural or artificialBanc associé à un objet flottant dérivant, naturel ou artificiel
UNCLUnknownInconnu
 

Measure types

MEASUREMENT_CODENAME_ENDESCRIPTION_ENNAME_FRDESCRIPTION_FR
FLUpper-jaw fork lengthStraight distance between the tip of the upper jaw and the fork of the tailLongueur de la fourche de la mâchoire supérieureDistance rectiligne entre l'extrémité de la mâchoire supérieure et la fourche de la queue
LJLower-jaw fork lengthStraight distance between the tip of the lower jaw and the fork of the tailLongueur mâchoire inférieure-fourcheDistance rectiligne entre l'extrémité de la mâchoire inférieure et la fourche de la queue
 

Raisings

RAISING_CODENAME_ENNAME_FR
OSOriginal sampleÉchantillon original
SDData raisedDonnées extrapolées
UNCLUnclassifiedNon classifié

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