Update on operational longline observer data required under resolution C-19-08 and a preliminary assessment of data reliability for estimating total catch for bycatch species in the eastern Pacific Ocean (DRAFT)
Over the past 3 years, the IATTC staff have worked together with CPCs to incrementally refine the data reporting requirements for large-scale tuna longline fishing vessels (LSTLFVs) to enable IATTC scientific staff to enhance the reporting of non-target species (i.e. “bycatch”) for the Ecosystem Considerations report and the Fishery Status Report. However, these improved data are also intended to be used to improve the quality of scientific research and assessments involving the fishery, in particular ecological risk assessment, and to improve the transparency of data for compliance under relevant IATTC Resolutions. In 2017, the IATTC staff proposed the establishment of minimum data standards for longline observer programs under Resolution C-11-08 (SAC-08-07e). At the eighth meeting of the Scientific Advisory Committee, the proposal was adopted, and CPCs agreed to provide those data for 2013–2017, and for subsequent years. The measures were subsequently incorporated into Resolution C-19-08 that entered into force in July 2019. There have been positive advances in longline data reporting over the past two years. The most notable improvement in data reporting has been the agreement by IATTC Members to submit operational-level observer data using an expanded set of data fields, which have been required of IATTC CPCs by the WCPFC since 2016 (WCPFC, 2016; Attachment F) when reporting observer data for sets made in the WCPO. Further data reporting improvements include the adoption of number of hooks as the metric by which longline fishing effort is to be measured in the EPO, as well as the use of a standardized reporting template that summarizes key elements of observer activities that is transparent in demonstrating compliance under Resolution C-19-08. In particular, this relates to the mandates of a minimum of 5% observer coverage of the total annual effort by each CPC’s fleet of longline vessels greater than 20 m length overall (LOA), and that the coverage is “…representative of the activities of its fleet, including in terms of gear configuration, target species and fishing areas representing of the activities of the fleet”. The current requirement of 5% observer coverage of the longline fleet has been a concern for IATTC research staff for several years given the results of studies conducted as far back as 1996 that recommended a minimum observer coverage of 20% for the Hawaii-based longline fleet (Skillman et al. 1996). Since this time, the recommended minimum coverage levels have been increased to be 40% and 80% to sufficiently monitor the catch rates for bycatch species that have a low incidence of capture in the American Samoa longline fishery (McCracken 2006) and the Hawaiian shallow-set longline fishery (McCracken 2012), respectively. Consequently, since 2017 the staff has annually recommended to the SAC that observer coverage for the longline fleet should be increased to 20% (IATTC-92-04c; p. 4), which has not been supported by the Members. Considering growing evidence of the potential inadequacy of current observer coverage in the EPO, the objectives of this paper were to: i) fulfil the recommendation by the SAC at its tenth meeting to provide a summary of the operational-level longline observer data for LSTLFVs >20m LOA received to date by the IATTC, and reporting of the percent observer coverage for 2020 as required under Resolution C-19-08 (see Annex A), ii) determine whether the current requirement of 5% observer coverage of LSLFVs under Resolution C-19-08 is sufficient to characterize the activities of LSTLFVs in the EPO and facilitate the reliable estimation of total annual catches for bycatch species for inclusion in the IATTC’s annual Ecosystem Considerations report and Fishery Status Report.