This dataset lists catch of tuna, tuna-like and shark species by purse seiners and pole-and-liners from 1950 to 2015 in the Indian, Atlantic and Eastern Pacific Oceans. Catches are stratified by month, species, gear, vessel flag reporting country, fishing mode (i.e. type of school used), area (1° square) and unit of catch (weight or number). This dataset was computed using public domain catch-and-effort datasets released by four of 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 Commission for the Conservation of Southern Bluefin Tuna (CCSBT). Data from the Western Pacific Ocean were not included because WCPFC provides purse seine and pole-and-line catch at 5° square spatial resolution.

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).
• 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.

In addition, data that were provided at resolutions superior to 1° x 1° were disaggregated to the corresponding 1° x 1°quadrants by dividing the catch equally on the overlappings 1° x 1°quadrants.

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 : - 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. - 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. - 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 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. - Some data can be expressed at temporal resolutions greater than 1 month.