Evaluation of the potential impact of catch underreporting on yellowfin stock assessment using exploratory scenarios of catch history

In 2018, a new stock assessment was carried out for yellowfin in the IOTC area. The uncertainty on nominal catches among others, recommended to avoid catch limits recommendation and the development of a workplan to address these uncertainties. One of the objectives of the workplan is to address the potential impact of the uncertainty on catches by exploring alternative scenarios of catch histories for yellowfin. In this study, we carried out a relatively simple exploratory analysis of the potential impact of underreporting of artisanal fisheries. We generated three scenarios of underreporting and re-run the stock assessment model. Our results suggest that the uncertainty in the catch information used in the stock assessment does not produce a noticeable impact on the estimates of stock status. Our results do suggest that changes in catch scenarios produce changes in the estimated productivity of the stock.