1. Why did you choose the topic for the poster?

This poster relates to the wider topic of my PhD, which focuses on exploring social-ecological tipping points and nonlinearities in delta systems. The Chilika lagoon of the Mahanadi delta, India, captured my interest due to its historical productivity collapse from 7200 tonnes/year (1980s average) to 3100 tonnes/year (1990s average), triggering declined fisher wellbeing, livelihood opportunities and the first recorded instances of economic migration from the region. Therefore, this poster communicates progress (September 2016) on the development of a systems dynamics model of Chilika’s fishery, to assess the causes and probabilities of future productivity collapses. The model’s structure and parameters show how the different components of the system fit together. The small section on model performance analysis argues that the model is capable of reproducing historical fishery trends. Thirdly, initial findings show that the model is producing realistic and policy relevant outputs, which may eventually inform the future governance of Chilika’s fishery.

2. What data sources have you used for the analysis?

The construction of the model has relied on a combination of quantitative and qualitative data, from a mix of primary and secondary sources:

• The rainfall-runoff models of the Lower Mahanadi and Chilika’s western catchments are built from daily resolution rainfall and temperature datasets from the Indian Meteorological Department (IMD). Daily river discharge from Tikarapara on the Lower Mahanadi catchment is obtained from the Indian Central Water Commission’s ‘Water Resource Information System of India’.
• Ecohydrological monitoring datasets of the Chilika Development Authority (CDA) parameterise interactions between freshwater inflows to Chilika and lagoonal salinity, dissolved oxygen, temperature and aquatic vegetation coverage.
• CDA datasets also inform the model’s socioeconomic components, including estimations of fisher populations, boat numbers, fish price, fishing costs, catch per unit effort and so on.
• Interviews were conducted with Chilika’s stakeholders and experts to understand any qualitative feedbacks driving Chilika’s fishery catch. For example, Chilika’s fishers spoke of how they adapt fishing efforts to their perceptions of fish stock abundance, in an attempt to protect against overexploitation of Chilika’s resource. Moreover, interviews with Chilika’s scientists and governors have helped consider feasible management approaches to model, such as the necessity of continued sediment dredging and the difficulties of implementing productivity quotas.
• With the exception of the hydroclimatic datasets, all data was obtained during the field visit of February-April 2016. I express gratitude to the CDA, Integrated Coastal Zone Management Project of Odisha and Jadavpur University for their kind assistance during my visit.

3. What’s the significance of your conclusions?

The model’s outputs have two main significances:

• Although known since the lagoon’s ecorestoration in 2000, outputs support the argument that Chilika’s sediment requires periodic flushing to sustain fish catches. Without reopening, the lagoon’s main tidal outlet effectively closes by 2040, inhibiting the seasonal migration of 70% of Chilika’s marine and brackish species.
• Outputs also show that higher annual catches do not necessarily mean higher income for Chilika’s fishers. Fish catch may decline beyond 2060 as fishers pursue alternative livelihoods, but per capita income is higher than it would otherwise be under a future without alternative livelihoods. By guarding against anthropogenic overexploitation, such falling catches promote the multidecadal sustainability of Chilika’s fish stock for future generations of fishers.
  Further work aims to assess how alternative governance approaches can enhance Chilika’s sustainability under a spectrum of plausible futures, before investigating critical driver thresholds leading to collapse, to design a “regional safe and just operating space” for Chilika.

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