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Inputs for stock assessment - Bigeye tuna (BET)

Reference: 
IOTC-2025-WPTT27-DATA07
File: 
Package icon IOTC-2025-WPTT27-DATA07_SABET.zip
Type: 
Datasets
Year: 
2025
Meeting: 
Working Party on Tropical Tunas (WPTT)
Meeting session: 
27
Availability: 
13 October 2025
Authors: 
IOTC Secretariat
Abstract: 

All datasets are used in the base SS3 stock assessment model, for 2025. There may be variations in parameters such as CV. All datasets are described in the assessment report, and further information regarding aggregation or allocation to various fleets and/or areas can be found either in the report, or by contacting the IOTC Secretariat (Genevieve Phillips - see above for contact details).

1)DATASET SS3catch.csv : raised catches for bigeye tuna in tonnes. Catch is from 1975-2024 inclusive. See Data Team at IOTC Secretariat if you need further information on the data used to create the assessment input.

YearQtr: refers to model quarters - see assessment report for more information.
season: for SS3 - there is only 1 'season' in the model.
ModelFleet: refers to the modelfleet. See assessment report (Table 1) for more information,and the table included below.
Region: refers to the assessment areas - see report for more details (Figure 1). Note that catch may not have been actively taken from this particular region - catch (like the fleet above) are aggregated based on fleet dynamics (similar gears and fishing behaviour are grouped together).

Any -999 values are essential for SS3 model running [see SS3 User Manual] - but can be removed if not needed / using another model where these delineating values are not required.

ModelFleet
1 = FL2 (longline, fresh tuna fleets; region 2)
2 = LL1N (longline, frozen tuna; region 1N)
3 = LL1S (longline, fronzen tuna; region 1S)
4 = LL2 (longline, frozen tuna; region 2)
5 = LL3 (longline, frozen tuna; region 3)
6 = PSFS1N (purse seine, free schooling; region 1N)
7 = PSFS1S (purse seine, free schooling; region 1S)
8 = PSFS2 (purse seine, free schooling; region 2)
9 = PSLS1N (purse seine, FAD-associated sets; region 1N)
10 = PSLS1S (purse seine, FAD-associated sets; region 1S)
11 = PSLS2 (purse seine, FAD-associated sets; region 2)
12 = BB1N (bait boat, small-scale encircling gears - eg. PSS/RN; region 1N)
13 = LINE2 (mixed line gears (handline, gillnet/longline combination; region 2)
14 = OT1N (other, trolling, gillnet, unclassified; region 1N)
15 = OT2 (other (trolling, gillnet, unclassified; region 2)

----------------------------------------------------------------------------------

2) DATASET SS3CPUE_all.csv : all CPUE indices used in the SS3 stock assessment. Note that this includes both purse seine, and longline CPUE indices, although the base models only include the CPUE indices from the longline fleets.

qtr: refers to YearQtr in model.
season: set to constant value (only 1 season in model)
fleet: additional fleets are used in the SS3 model for the cpue indices (as they represent a subset of the fleets in the catch fleets above)
cpue: catch per unit effort. See papers on the individual cpue indices to learn more about the standardisation process for these values.
cv: standard error around the cpue. See the stock assessment report for more information.

fleet
16 = LL index region 1S - area 1
17 = LL index region 2 - area 2
18 = LL index region 3Q1 - area 3
19 = LL index region 3Q2 - area 3
20 = LL index region 3Q3 - area 3
21 = LL index region 3Q4 - area 3
22 = LL index region 1N - area 4
23 = PSLS index (purse seine, FAD-associated sets; region 1S - area 1)
24 = PSLS index (purse seine, FAD-associated sets; region 1N - area 4)

-----------------------------------------------------------------------------------

3) DATASET SS3LFinput.csv : Length frequency data used in the SS3 stock assessment. Note that sample sizes are effective sample sizes (ESS), not actual sample sizes. Please see the stock assessment report for more information on how these were calculated.

Yr: refers to YearQtr in model.
Seas: model season
ModelFleet: as described in the catch dataset above.
Gender: fish sex: see SS3 User Guide for more information.
Part: SS3 required value. See SS3 User Guide for more information.
Nsamp: number of samples - note this is ESS, not actual sample sizes.
L010:L198: length bins (4 cm) used in the SS3 stock assessment. Numbers of fish in each bin relate to actual numbers of fish measured. Please see the report for more information.

Tags: 
bigeye tuna
Stock assessment
Stock synthesis 3

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