In Support of the IOTC Ecosystem Report Card: Advances in Monitoring the Impacts on and the State of the “Foodweb And Trophic Relationships” Ecosystem Component

In support of the development of the IOTC ecosystem report card, this paper addresses the “food web/trophic relationships” ecosystem component and specifically it contributes towards developing the following elements: (1) We describe the importance of this ecosystem component and explain the potential risks of not monitoring it, and make a proposal of a conceptual and an operational objective to measure progress towards monitoring the impacts of IOTC fisheries on and the state of this ecosystem component. (2) We present candidate ecological indicators that could be estimated to capture and describe changes in multiple ecosystem attributes of the marine ecosystem derived from the impacts of fisheries, and discuss main challenges in indicator development. (3) We also present three preliminary ecological indicators, which examine the potential ecological effects of the European and Seychelles purse seine fishery targeting tropical tunas in the western Indian Ocean, to monitor this ecosystem component. The three indicators describe the total biomass removed by this fishery in terms of weight, trophic level and replacement time of the species. (4) Finally, we draft a work plan to guide our future work. We invite the IOTC community and others to contribute towards the development of the IOTC ecosystem report card. If interested, contact the corresponding authors to find out how you can contribute to this initiative.