DOI: 10.5281/zenodo.1164128
title: Global monthly catch of tuna, tuna-like and shark species (1950-2015) aggregated by 1° or 5° squares (IRD level 2)

description: This dataset lists global catch of tuna, tuna-like and shark species from 1950 to 2015. Catches are stratified by month, species, gear, vessel flag reporting country, fishing mode (i.e. type of school used), area (mainly 1° or 5° square) and unit of catch (weight or number). This dataset was computed using public domain catch-and-effort datasets released by the five tuna Regional Fisheries Management Organizations: the Indian Ocean Tuna Commission (IOTC), the International Commission for the Conservation of Atlantic Tunas (ICCAT), the Inter-American Tropical Tuna Commission (IATTC), The Western and Central Pacific Fisheries Commission (WCPFC), the Commission for the Conservation of Southern Bluefin Tuna (CCSBT).

IRD Level 2 stands for the processes applied to the primary datasets by the French National Research Institute for Sustainable Development (IRD) to generate the dataset. These processes for level 2 at global scale are :

- Catch-and-effort data are disseminated in such way that redundancy may exist between the various datasets released, or that dimensions may be split over the datasets for some strata. To cope with these issues and get one single and more complete possible value of catch per stratum (i.e. with all the available dimensions), these datasets had to be merged in specific ways - i.e. not simply merging them but removing the duplicated strata or reassembling the strata with all the available dimensions split over the datasets.
- Values expressed in weight were kept and numbers were converted into weight using simple conversion matrices (A. Fonteneau, pers. com). These conversion factors depend on the species, the gear, the year and the main geographical area (equatorial or tropical). They were computed from the Japanese and Taiwanese size-frequency data as well as from the Japanese total catches and catch-and-effort data. Some data might not be converted at all because no conversion factor exists for the stratum: those data were kept and the unit of catch was set to Number of fishes harvested. Some data might not be converted at all because no conversion factor exists for the stratum: those data were kept and the unit of catch was set to Number of fishes harvested.
- Geo-referenced catches were raised to the total catches.
- Data located at land or without any spatial information were equally redistributed on data at sea on areas with same characteristics (same year, month, gear, flag, species, type of school).
- In the overlapping zone between the IATTC and the WCPFC, only data from the IATTC was kept (i.e. for this specific zone, data from the WCPFC was removed). IATTC data was kept rather than WCPFC's because the information on vessel flag reporting country is available in IATTC datasets contrary to WCPFC's ones.
- For the Southern Bluefin Tuna, only data from the the Commission for the Conservation of Southern Bluefin Tuna (CCSBT) was kept (i.e. data from the other RFMOs for SBF was removed).
- Original code lists have been mapped with standard FAO code lists (for gears, species, flags). These mappings have been done in collaboration with the RFMOs secretariats.

More details on the processes are provided in the lineage section.

Caracteristics, specific issues and problems that need to be taken into account :

In addition to the respective specific issues of all the tuna RFMOs datasets, the following issues might be taken into account :
- Stratification by vessel flag reporting country is not available for the Western Pacific Ocean. This is due to WCPFC confidentiality policies.
- Shark catches are not available for the Western Pacific Ocean, because WCPFC does not provide georeferenced shark catches.
- Data provided in number of fishes harvested in the Western Pacific Ocean were not converted into weight of fishes, because no factors of conversion are available for this Ocean.
- Data provided in number of fishes harvested for the Southern Bluefin tuna (SBF) were not converted into weight of fishes, because no factors of conversion are available for this species. This might represent a great amount of the data for SBF.
- For confidentiality policies, information on flag and school type for the geo-referenced catches is available in separate files for East Pacific Ocean (IATTC) Purse seine datasets. For each stratum, the catch from the flag-detailed dataset was raised to the catch from the school type-detailed dataset to get an estimation of the catches by flag and school type in each stratum.
- Geo-referenced catches were raised to the total catches for all tRFMOs. Depending on the availability of the flag dimension (currently not available for the geo-referenced catch-and-effort dataset from the Western-Central Pacific Ocean), the dimensions used for the raising are either {Flag, Species, Year, Gear} or {Species, Year, Gear}. Some catches cannot be raised because the combination {Flag, Species, Year, Gear} (resp. {Species, Year, Gear}) does exist in the geo-referenced catches but the same combination does not exist in the total catches. In this case, non-raised catch data were kept. Most catch-and-effort data have catches inferior to the catch available in the nominal catch dataset for a given stratum. However, in some cases the value of catch in the catch-and-effort data can be greater than the one in the nominal catch. In this case, the catch was 'downgraded' to the nominal catch one.
- Some codes could e mapped to standard code lists, for some tRFMOs own-defined codes that usually are aggregation of existing codes (e.g. flag IDPH - Indonesia and Philippines for WCPFC; species Otun - other tuna for ICCAT). In those cases, the code for species was set to UNK (Unknown). However, these codes have been mapped with more aggregated code lists i.e. group of species.
- Some data can be expressed at temporal resolutions greater than 1 month.
description: Step 1 - Public domain datasets from IOTC were collated (through the RFMO website). Their structure (i.e. column organization and names) was harmonized and they were loaded in the Tuna atlas database.
Step 2 - Public domain datasets from ICCAT were collated (through the RFMO website). Their structure (i.e. column organization and names) was harmonized and they were loaded in the Tuna atlas database.
Step 3 - Public domain datasets from IATTC were collated (through the RFMO website or sent be e-mail). Their structure (i.e. column organization and names) was harmonized and they were loaded in the Tuna atlas database.
Step 4 - Public domain datasets from WCPFC were collated (through the RFMO website). Their structure (i.e. column organization and names) was harmonized and they were loaded in the Tuna atlas database.
Step 5 - Public domain datasets from CCSBT were collated (through the RFMO website). Their structure (i.e. column organization and names) was harmonized and they were loaded in the Tuna atlas database.
Step 6 - Concerns ICCAT purse seine datasets : ICCAT delivers two catch-and-efforts datasets for purse seiners: one that gives the detail of the type of school (Fad|Free school) for purse seine fisheries and that starts in 1994 (called Task II catch|effort by operation mode Fad|Free school) and one that does not give the information of the type of school and that covers all the time period (from 1950) (called Task II catch|effort). These data are redundant (i.e. the data from the dataset Task II catch|effort by operation mode are also available in the dataset Task II catch|effort) but in the latter, the information on the type of school is not available. Both datasets were combined to produce a dataset that covers the whole time period, with fishing mode information (Fad | free school).
Step 7 - Concerns IATTC purse seine datasets : For confidentiality policies, information on flag and school type for the geo-referenced catches is available in separate files for the eastern Pacific Ocean purse seine datasets. For each stratum, the catch from the flag-detailed dataset was raised to the catch from the school type-detailed dataset to get an estimation of the catches by flag and school type in each str
Step 8 - All the datasets were merged.
Step 9 - The units used to express the catches may vary between tRFMOs datasets. Catches are expressed in weight, or in number of fishes, or in both weights and numbers in the same stratum. Values expressed in weight were kept and numbers were converted into weight using simple conversion matrices (A. Fonteneau, pers. com). These conversion factors depend on the species, the gear, the year and the main geographical area (equatorial or tropical). They were computed from the Japanese and Taiwanese size-frequency data as well as from the Japanese total catches and catch-and-effort data. The methodology to compute these factors is available here: https://goo.gl/F7zGGs. Some data might not be converted at all because no conversion factor exists for the stratum: these data were kept in number. Information regarding the conversions of catch units for this dataset: 83.18 % of the the catches that were originally expressed in number have been converted into weight through the conversion factors. The catches that were originally expressed in number and that have been converted into weight represent 7.75 % of the whole catches in the resulting dataset.step10: Catch-and-effort data are data aggregated over spatio-temporal strata that are collected by the CPCs or the tRFMOs in some cases. Generally, catch-and-effort data are defined over one month time period and 1° or 5° size square spatial resolution. Following ICCAT, catch and fishing effort statistics are defined as "the complete species (tuna, tuna like species and sharks) catch composition (in weight  or/and in number of fish) obtained by a given amount of effort (absolute value) in a given stratification or detail level (stratum). T2CE are basically data obtained from sampling a portion of the individual fishing operations of a given fishery in a specified period of time." (ICCAT Task 2). Hence, geo-referenced catch data and associated effort can represent only part of the total catches. Geo-referenced catches were raised to the total catches for all tRFMOs. Depending on the availability of the vessel flag reporting country dimension (currently not available for the geo-referenced catch-and-effort dataset from the Western-Central Pacific Ocean), the dimensions used for the raising are either {Flag, Species, Year, Gear} or {Species, Year, Gear}. Some catches cannot be raised because the combination {Flag, Species, Year, Gear} (resp. {Species, Year, Gear}) does exist in the geo-referenced catches but the same combination does not exist in the total catches. In this case, non-raised catch data were kept. Most catch-and-effort data have catches inferior to the catch available in the nominal catch dataset for a given stratum. However, in some cases the value of catch in the catch-and-effort data can be greater than the one in the nominal catch. In this cas, the catch was 'downgraded' to the nominal catch one. Information regarding the raising process for this dataset: Before the raising process, 68.21 % of the catches of the nominal catch datasets were available in the catch-and-effort datasets. After the raising process, this percentage reached 69.54 %. This percentage might not be 100 because of the following reasons: i) 6.69 % of the catches available in the catch-and-effort dataset had no correspondance in the nominal catch (i.e. the strata exists in the catch-and-effort dataset but does not exist in the nominal catch dataset); ii) 37.14 % of the catches available in the nominal catch dataset had no correspondance in the catch-and-effort dataset (i.e. the strata exists in the nominal catch dataset but does not exist in the catch-and-effort dataset)step11: Some data might be mislocated: either located on land areas or without any area information. These data were equally redistributed on data at sea on areas with same characteristics (same year, month, gear, flag, species, type of school). Information regarding the reallocation of mislocated data for this dataset: The data that were mislocated represented 0.01 % of the whole catches expressed in weight in the dataset and 0.23 % of the catches expressed in number. 100 % of the catches that were mislocated were reallocated on areas at sea.step12: Concerns IATTC and WCPFC data. IATTC and WCPFC have an overlapping area in their respective area of competence. Data from both RFMOs may be redundant in this overlapping zone. In the overlapping area, data from IATTC were kept (i.e. for this specific zone, data from WCPFC was removed). Information regarding the data in the IATTC / WCPFC overlapping area: after the eventual other corrections applied, e.g. raisings, catch units conversions, etc., the ratio between the catches from IATTC and those from WCPFC was of: 1.12 for the catches expressed in weight and 0.1 for the catches expressed in number.step13: Concerns Southern Bluefin Tuna (SBF) data: SBF tuna data do exist in both CCSBT data and the other tuna RFMOs data. Data from CCSBT and the other RFMOs may be redundant. For the Southern Bluefin Tuna, data from CCSBT were kept (i.e. data from the other RFMOs for SBF were removed). Information regarding the SBF data: after the eventual other corrections applied, e.g. raisings, catch units conversions, etc., the ratio between the catches from CCSBT and those from the other RFMOs for SBF was of: 0.23 for the catches expressed in weight. A total of 17705487.62 fishes were available in the CCSBT datasets - while no data in number were available in the other RFMOs datasets - and were thus integrated in this dataset.step14: Coding systems and nomenclatures used to describe the data (e.g. gears, flags, species) may differ according to tRFMOs. Codes used by the tuna RFMOs in their respective datasets were mapped to global code lists (ISSCFG, ISO3 countries codes, ASFIS). These mappings have been done with the collaboration of the Secretariats. Some codes could not have been mapped to standard code lists, for some tRFMOs own-defined codes that usually are aggregation of existing codes (e.g. flag "IDPH" - Indonesia and Philippines – for WCPFC; species "Otun" - other tuna – for ICCAT). In those cases, the code for species was set to UNK (Unknown). However, these codes have been mapped with more aggregated code lists – i.e. group of species. Information regarding the data that have species set to Unknown (i.e. data for which raw species do not have any correspondence in ASFIS): the catches that have species set to Unknown represent 3.79 % of the catches expressed in weight and 1.99 % of the catches expressed in number of fishes.step15: The CSV file was integrated into the Tuna atlas database.