The development of the seabird component of the IOTC ecosystem report card

This paper serves as a contribution to the development of the IOTC Ecosystem Report Card by outlining the context and providing proposals for the seabird bycatch component of the report card. We highlight that bycatch is considered one of the main impacts of IOTC fisheries on seabirds and emphasise the importance of monitoring seabird bycatch associated with IOTC fisheries. We note that IOTC fisheries may also have indirect impacts on seabirds through overexploitation of large subsurface predators (e.g. tuna and billfish), leading to reductions in the accessibility of seabird prey. Although this aspect is not considered further in the document, we highlight the need to develop appropriate indicators. Following the format adopted at WPEB14, we propose conceptual and operational objectives, and a list of candidate indicators. These include two high-level indicators (bycatch rates per unit effort, and an estimate of the total number of seabirds killed), together with a third indicator (use and effectiveness of bycatch mitigation measures) to facilitate the interpretation of trends in the other two, and to help inform an adaptive approach to the management of seabird bycatch in IOTC fisheries. We also underline the need to include an indicator measuring the risks, or population-level impacts, of bycatch for seabirds. We outline the uncertainties and limitations associated with the suite of indicators, most of which relate to the availability of appropriately collected and reported data. It is imperative that efforts are directed to improving the data available for these indicators. However, this should not hold back the process to monitor the impacts of IOTC fisheries on seabirds, and to help inform and support efforts to minimise these impacts. Improvements in the quantity and quality of data will lead to enhancements in the indicator system and its usefulness for informing management decisions. Even with imperfect data, the indicators and ecosystem report card will help highlight data gaps and priorities for further monitoring, and thus strengthen the report card tool over time.