1. Where does my data go? IOTC Data Revisions

2. Role of the IOTC Data section  The IOTC Secretariat Data Section plays an important role in assessing the compliance of countries submitting data in the correct format, at the correct level of disaggregation (temporal and spatial), in accordance with IOTC Resolutions.  The Data Section also independently validates the quality of data submitted, and when necessary, revises catch series in order to improve the accuracy of data used for scientific estimates.  Data revisions by the IOTC Secretariat – supported by capacity building activities – are an iterative process aimed at long-term improvements in the collection and quality of data from IOTC member countries.  Countries have detailed local knowledge of the national fishery; while the IOTC Secretariat has a broader knowledge of fisheries in the sub-region and an overview of catch trends and reporting issues across IOTC members.  The data revision process and assessment of the quality and coverage of data returns more generally helps the Secretariat to identify weaknesses in the IOTC statistical base and opportunities for future capacity building in countries.

3. Why does the IOTC Secretariat need to revise or estimate data? 1.Non-reporting countries - catches still need to be estimated. 2.Historical data revisions: improvements to historical catch series submitted by national fisheries organizations themselves. 3.Reported data is only partially complete or reported at an aggregated level that needs to be disaggregated to meet the minimum IOTC data requirements, e.g.,: -aggregated species groups – e.g., BILL, KGX, TUN, SHK -no information on fishery (gear) by species 4.Conflicting information published various marine and fisheries organizations from within a country. IOTC Data Section evaluates the reliability of different estimates and updates the data accordingly. 5.Data input errors– e.g., digit errors, or values entered in the wrong cells for individual species/gear, etc., in submitted data. 6.Data reported in the non-standard units – requires conversion by IOTC Secretariat (e.g. catches reported as processed weights) 7.Catch-and-effort data not raised – needs to be adjusted by IOTC in order to combine with data from other countries. 8.Alternative third party sources providing additional information on (reported or unreported), or more accurate catch estimates.

4. Revision and validation of IOTC data needs, to some extents, be at the level of the sub-regional level.

5. Data revisions process Countries are the first point of contact to resolve immediate queries with the data –but often time-consuming and difficult to resolve complex issues by email. The IOTC Data Section will – when considered justified – adjust the data with the aim of improving the accuracy of catch statistics. Data submitted by countries can remain pending upload to the IOTC database, until the IOTC Data Section is content with the reliability of information. Major revisions to countries’ data by the IOTC Secretariat will, whenever possible, be sent to countries for peer review in addition with an explanation of the methodology of new estimates. Substantial revisions to catch series are also presented annually to the relevant Working Parties and Scientific Committee for endorsement as scientific estimates. Opportunities to directly address data issues by the IOTC Secretariat and member countries are available at the Working Parties and SC.

6. Data revisions process ReminderReviewFinal estimates Data by the standards, not conflicting or inconsistent Data reported Fishing Party Data fall short of standards, conflicting or inconsistent Adopted by SC Best estimates Alternative data available Data NOT reported Alternative data NOT available Catch estimated by the Secretariat REJECTED by SC

7. Common estimation methods 1.Missing or non-reported data estimated according to previous years’ catch, overall trend in catch series, or by fixed ratios for individual species. 2.Use of proxy fleets to determine nominal catch trends (e.g., % change in catch for individual species, species composition). 3.Substitution of catches from proxy fleets (e.g, raised size frequency data). 4.Alternative information and data from third party sources (e.g., IPTP, FAO FishSTAT, ISSF). 5.IOTC independent studies of countries (e.g., IOTC-OFCF, BOBLME projects) 6.Latest data, or knowledge of fishery, presented by national scientists at Working Parties. 7.Published (aggregated) data – area/species/gear allocation by IOTC, using substitution or proxy fleets. 8.Published data, raised by IOTC.  Whenever possible, the IOTC Secretariat adjusts the catch by species or gear, (rather than adjusting the TOTAL nominal catch reported by countries).

9. IOTC Data Section quality checklist Consistency in the catch series – comparison to previous years’ data to assess changes in the catch-series or species composition against known changes in the fishery. Coherence with related datasets: combining information from different data-sets, e.g.: -calculating average catches per vessel (no. of fishing craft with nominal catch); -for SF samples where lengths and weights are both collected, comparison of length-frequency derived average weights with observed/estimated weights; -comparison of average weights (derived from length frequency samples) with catch-and-effort (numbers / weights of fish) by time-area; -cross-check different units of effort (where multiple effort measures are collected). Comparison of catch trends, species composition with those of neighbouring countries with similar fisheries. Comparison of data with alternative or third party datasets (e.g., FAO FISHSTAT, ISSF). Metadata: catch sampling, data processing and methodology of raising catch estimates by time-area are fully documented.

10. IOTC Data Section quality checklist Practical steps on improving the quality rating of data submitted to IOTC Secretariat: Reporting of data 1.Data is submitted on time according to deadlines agreed by the Commission. 2.Data is fully reported according to standards set out in IOTC Resolutions, including: -catches or domestic and foreign fleets are reported separately; -catches for coastal fisheries are also reported separately from total nominal catches. 3.Aggregation by fishery (gear) and species should be avoided wherever possible. Provide as much detail as possible on the original data. 4.Detail the data collection and processing steps in compiling data when submitting statistical returns to the IOTC Secretariat to improve transparency. 5.Revisions to the historical data series are provided to the IOTC Secretariat as they become available.

11. Discussion