Available datasets

IOTC holds a number of databases, the principal tables of which are listed below. The data, on a flag state basis, are supplied by both contracting and non-contracting parties fishing for tunas in the Indian Ocean (IOTC Resolution 15/02 On Mandatory Statistical Requirements). These statistical data are under constant review and users are strongly urged to contact the Secretariat for the most recent holdings. Most of the data are in the public domain, but the distribution of certain detailed data sets is restricted to preserve confidentiality (IOTC Resolution 12/02 On Data Confidentiality Policy and Procedures).

Latest data published by IOTC Secretariat

Details about each dataset are given below. Revisions to the historical data series are released periodically to reflect improvements in the accuracy of catch estimates reported by each country. Users are advised to check the IOTC website for the latest data.

Description of datasets available at the IOTC Secretariat

Nominal catch (NC)

This table lists annual catches for each IOTC statistical area, by species and fishing gear made by vessels flying the flag of the reporting country in live weight equivalent. These data are aggregated by calendar year for tuna and tuna-like species and non-target species (by-catch). The data set extends back to the 1950’s when industrial longlining started in the Indian Ocean. The data are in the public domain. Nominal catches are available in spreadsheet format (Microsoft excel) both for IOTC species and sharks. Please, refer to the worksheet NOTES within the downloadable spreadsheet if you want to use this dataset.

Note that the catch estimates in this data file differ from the ‘best scientific estimates’ of nominal catch used for stock assessment purposes and published on the dedicated meeting pages for each IOTC Working Party.  The best scientific estimates disaggregates catches recorded under species or gear aggregates recorded in the IOTC database reported by countries, which are then assigned by species or gear when the Secretariat has access to alternate sources of information such as statistical publications, fishery bulletins or other information.  For this reason, catches by individual species or gear published on the IOTC meeting pages may differ from the nominal catches available from the data file available here.

Discard levels (DS)

This table covers discards by vessels flying the flag of the reporting country in number or live weight equivalent (discards corrected by adding weight losses due to predation, etc.) These data are normally aggregated by calendar year for each IOTC statistical area for both target and non-target species, by species and fishing gear. These data are not routinely reported to the IOTC, other than trip reports from the IOTC Regional Observer Scheme. Estimates of levels of discards are not available for all fleets and species groups (IOTC species, sharks, seabirds, marine turtles, marine mammals, and other marine species) and the datasets available do not contain the information required to derive estimates of discard levels for the Indian Ocean as a whole.

Catch and effort (CE)

This table lists catch in weight (purse seine) and/or numbers of fish (longline) of tuna and tuna-like species, preferably raised to the total nominal catch and fishing effort by month, species and gear. The maximum spatial aggregation should be by 1°x1° grid area for purse seine and 5°x5° grid area for longline. This is not, however, the case with all CE data available: CE data recorded for most artisanal fleets refers to irregular areas (e.g. CE data recorded per port of unloading).
Catches and effort are not available for all Nominal catches strata. When recorded, the catches in these datasets might represent the total catches of the species in the year for the fleet and gear concerned or represent simply a sample of those.
These data, as well as the length-frequency data listed below are considered to be in the public domain, provided that the catch of no individual vessel can be identified within a time/area stratum. In cases when an individual vessel can be identified, the data are aggregated prior to release by time, area or flag to preclude such identification, and will then be in the public domain.
Catch-and-effort and length-frequency data grouped at a finer level of time-area stratification are only released with written authorization from the sources of the data and are subject to a number of constraints destined to preserve confidentiality.
CE data are available in text (CSV) format. Please, refer to the detailed CE reference if you want to use this dataset.

Size-frequency (SF)

Length-frequency sample or raised data by species and gear are kept in the smallest practicable time/area strata. The spatial and temporal aggregation are identical to those of the catch and effort data, as are the restrictions on release.
Please refer to the detailed SF reference if you want to use these datasets.
Detailed SF data are not presented here for download. Please refer to the Data Meeting Pages or contact the Secretariat to get access to these datasets.

Other biological data

Apart from information on the individual lengths or weights of IOTC species and sharks, the IOTC also collects other data on the biology of IOTC stocks, in particular:

• Data used to derive the equations necessary to convert from non-standard measurements into standard measurements, for each species [,fishery and time-period]  
• Data on the proportion of specimens by sex (sex ratio) for each species, length class [,fishery and time-period].
• Data on the maturity and fecundity of IOTC and related species.
• Other datasets, such are the data used to derive growth functions for IOTC stocks, natural mortality, etc.

Where not specified, please, contact the Secretariat for more information about the data that are available.

Tagging data (TD)

Data on the release and recovery of IOTC species, in particular tropical tunas, were obtained through the implementation of an EU-funded Regional Tuna Tagging Programme, and several other small-scale tagging projects. Please, contact the Secretariat for more information about the data that are available and procedures required to obtain this information.

Fishing craft statistics (FC)

This dataset lists the number of vessels operating under the flag of the reporting country catching tuna and tuna-like species by gear and size category within one calendar year. Foreign vessels chartered by or under joint venture arrangements with the reporting country are reported separately.  The data is organized by LOA (overall length) size categories.  In 2013 the IOTC Secretariat conducted a comprehensive review of the fishing craft statistics available for industrial vessels, with the objective of harmonizing the units and size class intervals used for industrial vessels.  The Fishing Craft Statistics database is in the process of being updated based on the results from this latest review (see the 2013 Fishing Capacity Report).

Socio-economic data (SD)

Provisions in Article V 2(d) of the IOTC Agreement state that the Commission shall “keep under review the economic and social aspects of the fisheries based on the stocks covered by this Agreement bearing in mind, in particular, the interests of developing coastal states;”  To date the Commission has not agreed on the type of socio-economic data, data resolution, and reporting timeframes that should be put in place for socio-economic data.  Please, contact the Secretariat for more information about the data that are available.

Datasets used for stock assessment

Please refer to the meeting pages of each Working Party to consult and download the datasets that were used for stock assessment:

• WP on Billfish (WPB)
• WP on Neritic Tunas (WPNT)
• WP on Temperate Tunas (WPTmT)
• WP on Tropical Tunas (WPTT)
• WP on Ecosystems and Bycatch (WPEB)